asynDriver: Asynchronous Driver Support

Release 4-27

Mark Rivers, Eric Norum, and Marty Kraimer

October 7, 2015

Other Contributers

Gasper Jansa (cosyLab) - linuxGpib support.


License Agreement

This product is available via the open source license described at the end of this document.


Contents

Purpose
Status
Acknowledgments
Overview of asynDriver
Theory of Operation
asynDriver Structures and Interfaces
Standard Message Based Interfaces
Standard Register Based Interfaces
asynStandardInterfacesBase
Standard Interpose Interfaces
Generic Device Support for EPICS records
asynRecord: Generic Record Support
Example
Test Example
asynGpib
Port Drivers asynPortDriver C++ base class
asynPortClient C++ classes
Diagnostic Aids
Install and Build

Purpose

asynDriver is a general purpose facility for interfacing device specific code to low level drivers. asynDriver allows non-blocking device support that works with both blocking and non-blocking drivers.

A primary target for asynDriver is EPICS IOC device support but, other than using libCom, much of it is independent of EPICS.

asynDriver has the following key concepts:


Status

This version provides

The following are some of the existing EPICS general purpose device support systems that have been converted to use asynDriver.


Acknowledgments

The idea of creating asynDriver resulted from many years of experience with writing device support for serial and GPIB devices. The following individuals have been most influential.

John Winans
John provided the original EPICS GPIB support. Databases using John's support can be used without modification with devGpib. With small modifications, device support modules written for John's support can be used.
Benjamin Franksen
John's support only worked on vxWorks. In addition, the driver support was implemented as a single source file. Benjamin defined an interface between drvCommon and low level controllers and split the code into drvGpib and the low level drivers. He also created the support for drvVxi11.
Eric Norum
Eric started with Benjamin's code and converted it to use the Operating System Independent features of EPICS 3.14.
Marty Kraimer
Marty started with Eric's version and made changes to support secondary addressing; and to replace ioctl with code to support general bus management, universal commands, and addressed commands.
Pete Owens
Pete, for the Diamond Light Source, did a survey of several types of device/driver support packages for serial devices. Diamond decided to use the StreamDevice support developed by Dirk Zimoch.
Dirk Zimoch
Dirk developed StreadDevice, which has a single device support model, but supports arbitrary low level message based drivers, i.e. GPIB, serial, etc.
Jun-ichi Odagare
Jun-ichi developed NetDev, a system that provides EPICS device support for network based devices. It has a single device support model, but provides a general framework for communicating with network based devices.
Mark Rivers
Mark became an active developer of asynDriver soon after he started converting SynApps to use asynDriver. He soon pushed to have asynDriver support synchronous drivers, support register based drivers, and support interrupts. With these additions asynDriver is a framework for interfacing to a large class of devices instead of just message based asynchronous devices.
Yevgeny A. Gusev
Yevgeny has found bugs and suggested improvements in the way asynManager handles queue timeouts and cancels. He provides an expert and welcome set of eyes to look at difficult code!!!

Overview of asynDriver

Definitions

asynDriver is a software layer between device specific code and drivers that communicate with devices. It supports both blocking and non-blocking communication and can be used with both register and message based devices. asynDriver uses the following terminology:

Synchronous/asynchronous and message/register are orthogonal concepts. For example a register based driver can be either synchronous or asynchronous. The terminology register vs message is adapted from VXI.

Standard interfaces are defined so that device specific code can communicate with multiple port drivers. For example if device support does all its communication via reads and writes consisting of 8 bit bytes (octets), then it should work with all port drivers that support octet messages. If device support requires more complicated support, then the types of ports will be more limited. Standard interfaces are also defined for drivers that accept 32 bit integers or 64 bit floats. Additional interfaces can be defined, and it is expected that additional standard interfaces will be defined.

One or more devices can be attached to a port. For example, only one device can be attached to an RS-232 port, but up to 15 devices can be attached to a GPIB port.

Multiple layers can exist between device specific code and a port driver. A software layer calls interposeInterface in order to be placed between device specific code and drivers. For more complicated protocols, additional layers can be created. For example, GPIB support is implemented as an asynGpib interface which is called by user code, and an asynGpibPort interface which is called by asynGpib.

A driver normally implements multiple interfaces. For example asynGpib implements asynCommon, asynOctet, and asynGpib.

asynManager uses the Operating System Independent features of EPICS base. It is, however, independent of record/device support. Thus, it can be used by other code, e.g. a sequence program.

Standard Interfaces

These are interfaces provided by asynManager or interfaces implemented by all or most port drivers.

The interfaces are:

asynManager provides services for communicating with a device connected to a port.

asynCommon is an interface that must be implemented by all low level drivers. The methods are:

asynTrace is an interface for generating diagnostic messages.

asynLockPortNotify is an interface that is implemented by a driver which is an asynUser of another driver. An example is a serial bus driver that uses standard serial support. asynManager calls asynLockPortNotify whenever it locks or unlocks the port.

asynDrvUser is an interface for communicating information from device support to a driver without the device support knowing any details about what is passed.

Generic Interfaces

In addition to asynCommon and optionally asynDrvUser, port drivers can implement one or more of the following message and/or register based interfaces.

asynOctet methods for message based devices

asynFloat64 methods for devices that read/write IEEE float values

asynFloat32Array methods for devices that read/write arrays of IEEE 32-bit float values

asynFloat64Array methods for devices that read/write arrays of IEEE 64-bit float values

asynInt32 methods for devices that read/write integer values. Many analog I/O drivers can use this interface.

asynInt8Array methods for devices that read/write arrays of 8-bit integer values

asynInt16Array methods for devices that read/write arrays of 16-bit integer values

asynInt32Array methods for devices that read/write arrays of 32-bit integer values

asynUInt32Digital methods for devices that read/write arrays of digital values. This interface provides a mask to address individual bits within registers.

asynGenericPointer methods for devices that read/write arbitrary structures, passed via a void* pointer. The client and the server of course need to agree on the structure type being pointed to.

asynManager

asynManager is an interface and associated code. It is the "heart" of asynDriver since it manages the interactions between device support code and drivers. It provides the following services:

Multiple Device vs Single Device Port Drivers

When a low level driver calls registerPort, it declares if it handles multiple devices. This determines how the addr argument to connectDevice is handled and what getAddr returns.

Connection Management

asynManager keeps track of the following states:

If the port does not support multiple devices, then port and device status are the same. If the port does support multiple devices, then asynManager keeps track of the states for the port and for every device connected to the port.

Whenever any of the states change for a port or device, then all users that previously called exceptionCallbackAdd for that port or device are called.

Low level drivers must call pasynManager:exceptionConnect whenever they connect to a port or port,addr and exceptionDisconnect whenever they disconnect.

Protecting a Thread from Blocking

The methods asynManager:report and asynCommon:report can be called by any thread, but the caller is blocked until the report finishes. lockPort, unlockPort, queueLockPort, queueUnlockPort, and most port methods may block. The other asynManager methods can be called by any thread including portThread. None of these methods block.

Unless stated otherwise the methods for other interfaces must only be called by processCallback or by calls between lockPort/unlockPort, or queueLockPort/queueUnlockPort.

Interface methods registerInterruptUser and cancelInterruptUser must never block. The registerInterruptUser callback must not block because it could be called by a non blocking driver.

portThread

If a driver calls asynManager:registerPort with the ASYN_CANBLOCK attributes bit set, then asynManager creates a thread for the port. Each portThread has its own set of queues for the calls to queueRequest. Four queues are maintained. One queue is used only for asynCommon:connect and asynCommon:disconnect requests. The other queues provide different priorities: low, medium, and high. queueRequests to any queue other then the connection queue will be rejected if the port is not connected. portThread runs forever implementing the following algorithm:

  1. Wait for work by calling epicsEventMustWait. Other code such as queueRequest call epicsEventSignal.
  2. If the port is disabled, go back to 1.
  3. For every element in queue, asynQueuePriorityConnect:
  4. For each element of the queues asynQueuePriorityHigh, ...,asynQueuePriorityLow.

The actual code is more complicated because it unlocks before it calls code outside asynManager. This means that the queues can be modified and exceptions may occur.


Theory of Operation

Initialization

During initialization, port drivers register each communication port as well as all supported interfaces.

User code creates an asynUser, which is a "handle" for accessing asynDriver facilities, by calling

    pasynManager->createAsynUser(processCallback,timeoutCallback);

An asynUser has the following features:

User code connects to a low level driver via a call to

    status = pasynManager->connectDevice(pasynUser,portName,addr);

This call must specify the name of the port and the address of the device. It then calls findInterface to locate the interfaces with which it calls the driver. For example:

     pasynInterface = pasynManager->findInterface(pasynUser,asynOctetType,1);

Requesting access to a port

User code can request access to a port by two methods:

queueRequest - Flow of Control

User code requests access to a port by calling:

    status = pasynManager->queueRequest(pasynUser,priority,timeout);

This results in either processCallback or timeoutCallback being called. Most requests to a port must be made from processCallback. queueRequest does not block. If queueRequest is called for a port that can block the request is queued to a thread dedicated to the port. If queueRequest is called for a port does not block it just calls processCallback. guarantee is valid only if low level drivers are only accessed by calling queueRequest, lockPort/unlockPort, and/or queueLockPort/queueUnlockPort

The following examples are based on EPICS IOC record/device support.

The first example shows access to a port that can block.

AsynFlow.jpg

Figure 1: Asynchronous Control Flow

The sequence of record device support events that occurs starting with an application thread is pictured above in Figure 1, and explained below in the following steps:

  1. Record processing calls device support with PACT 0 (Processing is not active).
  2. Device support calls queueRequest.
  3. queueRequest places the request on the driver work queue. The application thread is now able to go on and perform other operations. Subsequent operations for this I/O request are handled in the port driver thread.
  4. The portThread removes the I/O request from the work queue.
  5. The portThread calls the processCallback located in Record device support.
  6. processCallback calls the low-level driver. The low-level driver read or write routine blocks until the I/O completes or until a timeout occurs. The low-level driver routine returns the results of the I/O operation to processCallback.
  7. processCallback requests that the record be processed. NOTE: The process request will be made by one of the standard callback requests rather than the port thread.
  8. Record support calls device support again, this time with PACT 1(processing is active). Device support updates fields in the record and returns to record support which completes record processing.

The second example shows access to a port that cannot block.

AsynSynFlow.jpg

Figure 2: Synchronous Control Flow

The sequence of record device support events that occurs starting with an application thread is pictured above in Figure 2, and explained below in the following steps:

  1. Record processing calls device support.
  2. Device support calls queueRequest.
  3. Since the port is synchronous, i.e. can not block, queueRequest locks the port and then calls the processCallback.
  4. processCallback calls the low-level driver read or write routine. The low-level driver routine returns the results of the I/O operation to processCallback.
  5. processCallback returns to queueRequest, which unlocks the port and returns to device support, which returns to record support, which completes record processing.

asynDriver Structures and Interfaces

asynDriver.h describes the following:

asynStatus

Defines the status returned by most methods. If a method returns a status other than asynSuccess, and one of the arguments to the method is pasynUser, then the method is expected to write a message into pasynUser->errorMessage.

typedef enum {
    asynSuccess,asynTimeout,asynOverflow,asynError,asynDisconnected,asynDisabled
}asynStatus;
asynStatus
asynSuccess The request was successful.
asynTimeout The request failed with a timeout.
asynOverflow The driver has lost input data. This can happen if an internal buffer or the user supplied buffer is too small. Whenever possible, low level drivers should be written so that the user can read input in small pieces.
asynError Some other error occured.
asynDisconnected The request failed because the port is not connected.
asynDisabled The request failed because the port or device is disabled.

asynException

Defines the exceptions for method exceptionOccurred

typedef enum {
    asynExceptionConnect,asynExceptionEnable,asynExceptionAutoConnect,
    asynExceptionTraceMask,asynExceptionTraceIOMask,asynExceptionTraceInfoMask,
    asynExceptionTraceFile,asynExceptionTraceIOTruncateSize
} asynException;
asynException
asynExceptionConnect The connection state of the port or device has changed.
asynExceptionEnable The enable state of the port or device has changed.
asynExceptionAutoConnect The autoConnect state of the port or device has changed.
asynExceptionTraceMask The traceMask for the port or device has changed.
asynExceptionTraceIOMask The traceIOMask for the port or device has changed.
asynExceptionTraceInfoMask The traceInfoMask for the port or device has changed.
asynExceptionTraceFile The trace file for the port or device has changed.
asynExceptionTraceIOTruncateSize The traceIOTruncateSize for the port or device has changed.

asynQueuePriority

This defines the priority passed to queueRequest.

typedef enum {
    asynQueuePriorityLow,asynQueuePriorityMedium,asynQueuePriorityHigh,
    asynQueuePriorityConnect
}asynQueuePriority;
asynQueuePriority
asynQueuePriorityLow Lowest queue priority.
asynQueuePriorityMedium Medium queue priority.
asynQueuePriorityHigh High queue priority.
asynQueuePriorityConnect Queue a connect or disconnect request. This priority must be used for and only for connect/disconnect requests.

asynUser

Describes a structure that user code passes to most asynManager and driver methods. Code must allocate and free an asynUser by calling asynManager:createAsynUser (or asynManager:duplicateAsynUser) and asynManager:freeAsynUser.

typedef struct asynUser {
    char          *errorMessage;
    int            errorMessageSize;
    /* timeout must be set by the user */
    double         timeout;  /*Timeout for I/O operations*/
    void          *userPvt;
    void          *userData;
    /*The following is for user to/from driver communication*/
    void          *drvUser;
    /*The following are normally set by driver*/
    int            reason;
    epicsTimeStamp timestamp;
    /* The following are for additional information from method calls */
    int            auxStatus; /*For auxillary status*/
}asynUser;
asynUser
errorMessage When a method returns asynError it should put an error message into errorMessage via a call to:
epicsSnprintf(pasynUser->errorMessage,pasynUser->errorMessageSize,
              "<format>",...)
The error message should not end with (nor contain) a newline character sequence (e.g. \n). It is up to user code to decide whether and how to display the error message. Keeping newlines out of the error message make it easy for user code to embed the error message in another message or output format.
errorMessageSize The size of errorMessage. The user can not change this value.
timeout The number of seconds before timeout for I/O requests. This is set by the user and can be changed between calls to a driver. If a call to a low level driver results in the driver making many I/O requests this is the time for each I/O request.

The meaning is as follows:

> 0.0 Wait for up to timeout seconds for the I/O to complete

= 0.0 Peform any I/O that can be done without blocking. Return timeout error if no I/O can be done without blocking.

< 0.0 Infinite timeout. Wait forever for I/O to complete.

userPvt For use by the user. The user should set this immediately after the call to pasynManager->createAsynUser.

If this is changed while asynUser is queued, the results are undefined, e.g. it could cause a crash.

userData Also for use by the user.
drvUser A driver can use this to hold asynUser specific data. The asynDrvUser interface is used for communication between asynUser and the driver.
reason Drivers and asynUsers can use this as a general purpose field. By convention it is used to determine what "command" is being sent over a particular interface. For example an A/D driver implementing the asynInt32 interface might define reason=0 to mean "return the A/D conversion", while reason=1 might mean "return the amplifier gain". Typically drivers implement the asynDrvUser interface, and use this to convert from descriptive strings for commands (e.g. "DATA" or "GAIN" in this example) to the enum "reason". A driver that is calling an interrupt users often uses reason to decide if the users callback should be called. Values of reason less than 0 are reserved for standard meanings. For example ASYN_REASON_SIGNAL is used to mean "out of band" request. The devGpib support uses this to report SRQs.
timestamp Devices which provide their own time stamps use this field to provide the time value for records whose TSE field is set to "-2".
auxStatus Any method can provide additional return information in auxStatus. The meaning is determined by the method. Callbacks use auxStatus to set record alarm status in device support callback functions.

asynInterface

This defines an interface registered with asynPortManager:registerPort or asynManager:interposeInterface.

typedef struct asynInterface{
    const char *interfaceType; /*For example, asynCommonType */
    void *pinterface;          /*For example, pasynCommon */
    void *drvPvt;
}asynInterface;
asynInterface
interfaceType A character string describing the interface.
pinterface A pointer to the interface. The user must cast this to the correct type.
drvPvt For the exclusive use of the code that called registerPort or interposeInterface.

asynManager

This is the main interface for communicating with asynDriver.

/*registerPort attributes*/
#define ASYN_MULTIDEVICE  0x0001
#define ASYN_CANBLOCK     0x0002

/*standard values for asynUser.reason*/
#define ASYN_REASON_SIGNAL -1

typedef struct interruptNode{
    ELLNODE node;
    void    *drvPvt;
}interruptNode;

typedef void (*userCallback)(asynUser *pasynUser);
typedef void (*exceptionCallback)(asynUser *pasynUser,asynException exception);
typedef void (*timeStampCallback)(void *userPvt, epicsTimeStamp *pTimeStamp);

typedef struct asynManager {
    void      (*report)(FILE *fp,int details,const char*portName);
    asynUser  *(*createAsynUser)(userCallback process,userCallback timeout);
    asynUser  *(*duplicateAsynUser)(asynUser *pasynUser,
                                 userCallback queue,userCallback timeout);
    asynStatus (*freeAsynUser)(asynUser *pasynUser);
    void       *(*memMalloc)(size_t size);
    void       (*memFree)(void *pmem,size_t size);
    asynStatus (*isMultiDevice)(asynUser *pasynUser,
                                const char *portName,int *yesNo);
    /* addr = (-1,>=0) => connect to (port,device) */
    asynStatus (*connectDevice)(asynUser *pasynUser,
                                const char *portName,int addr);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*exceptionCallbackAdd)(asynUser *pasynUser,
                                       exceptionCallback callback);
    asynStatus (*exceptionCallbackRemove)(asynUser *pasynUser);
    asynInterface *(*findInterface)(asynUser *pasynUser,
                            const char *interfaceType,int interposeInterfaceOK);
    asynStatus (*queueRequest)(asynUser *pasynUser,
                              asynQueuePriority priority,double timeout);
    asynStatus (*cancelRequest)(asynUser *pasynUser,int *wasQueued);
    asynStatus (*blockProcessCallback)(asynUser *pasynUser, int allDevices);
    asynStatus (*unblockProcessCallback)(asynUser *pasynUser, int allDevices);
    asynStatus (*lockPort)(asynUser *pasynUser);
    asynStatus (*unlockPort)(asynUser *pasynUser);
    asynStatus (*queueLockPort)(asynUser *pasynUser);
    asynStatus (*queueUnlockPort)(asynUser *pasynUser);
    asynStatus (*canBlock)(asynUser *pasynUser,int *yesNo);
    asynStatus (*getAddr)(asynUser *pasynUser,int *addr);
    asynStatus (*getPortName)(asynUser *pasynUser,const char **pportName);
    /* drivers call the following*/
    asynStatus (*registerPort)(const char *portName,
                              int attributes,int autoConnect,
                              unsigned int priority,unsigned int stackSize);
    asynStatus (*registerInterface)(const char *portName,
                              asynInterface *pasynInterface);
    asynStatus (*exceptionConnect)(asynUser *pasynUser);
    asynStatus (*exceptionDisconnect)(asynUser *pasynUser);
    /*any code can call the following*/
    asynStatus (*interposeInterface)(const char *portName, int addr,
                              asynInterface *pasynInterface,
                              asynInterface **ppPrev);
    asynStatus (*enable)(asynUser *pasynUser,int yesNo);
    asynStatus (*autoConnect)(asynUser *pasynUser,int yesNo);
    asynStatus (*isConnected)(asynUser *pasynUser,int *yesNo);
    asynStatus (*isEnabled)(asynUser *pasynUser,int *yesNo);
    asynStatus (*isAutoConnect)(asynUser *pasynUser,int *yesNo);
    asynStatus (*setAutoConnectTimeout)(double timeout);
    asynStatus (*waitConnect)(asynUser *pasynUser, double timeout);
    /*The following are methods for interrupts*/
    asynStatus (*registerInterruptSource)(const char *portName,
                               asynInterface *pasynInterface, void **pasynPvt);
    asynStatus (*getInterruptPvt)(asynUser *pasynUser,
                               const char *interfaceType, void **pasynPvt);
    interruptNode *(*createInterruptNode)(void *pasynPvt);
    asynStatus (*freeInterruptNode)(asynUser *pasynUser,interruptNode *pnode);
    asynStatus (*addInterruptUser)(asynUser *pasynUser,
                                  interruptNode*pinterruptNode);
    asynStatus (*removeInterruptUser)(asynUser *pasynUser,
                                  interruptNode*pinterruptNode);
    asynStatus (*interruptStart)(void *pasynPvt,ELLLIST **plist);
    asynStatus (*interruptEnd)(void *pasynPvt);
    /* Time stamp functions */
    asynStatus (*registerTimeStampSource)(asynUser *pasynUser, void *userPvt, timeStampCallback callback);
    asynStatus (*unregisterTimeStampSource)(asynUser *pasynUser);
    asynStatus (*updateTimeStamp)(asynUser *pasynUser);
    asynStatus (*getTimeStamp)(asynUser *pasynUser, epicsTimeStamp *pTimeStamp);
    asynStatus (*setTimeStamp)(asynUser *pasynUser, const epicsTimeStamp *pTimeStamp);

    const char *(*strStatus)(asynStatus status);
}asynManager;
epicsShareExtern asynManager *pasynManager;
asynManager
report Reports status about the asynPortManager. If portName is non-NULL it reports for a specific port. If portName is NULL then it reports for each registered port. It also calls asynCommon:report for each port being reported.
createAsynUser Creates an asynUser. The caller specifies two callbacks, process and timeout. These callback are only called as a result of a queueRequest. The timeout callback is optional. errorMessageSize characters are allocated for errorMessage. The amount of storage can not be changed. This method doesn't return if it is unable to allocate the storage.
duplicateAsynUser Creates an asynUser by calling createAsynUser. It then initializes the new asynUser as follows: The fields timeout, userPvt, userData, and drvUser are initialized with values taken from pasynUser. Its connectDevice state is the same as that for pasynUser.
freeAsynUser Free an asynUser. The user must free an asynUser only via this call. If the asynUser is connected to a port, asynManager:disconnect is called. If the disconnect fails, this call will also fail. The storage for the asynUser is saved on a free list and will be reused in later calls to createAsynUser or duplicateAsynUser. Thus continually calling createAsynUser (or duplicateAsynUser) and freeAsynUser is efficient.
memMalloc

memFree

Allocate/Free memory. memMalloc/memFree maintain a set of freelists of different sizes. Thus any application that needs storage for a short time can use memMalloc/memFree to allocate and free the storage without causing memory fragmentation. The size passed to memFree MUST be the same as the value specified in the call to memMalloc.
isMultiDevice Answers the question "Does the port support multiple devices?" This method can be called before calling connectDevice.
connectDevice Connect the asynUser structure to a device specified by portName, addr. The port Name is the same as that specified in a call to registerPort. The call will fail if the asynUser is already connected to a device. If the port does not support multiple devices, than addr is ignored. connectDevice only connects the asynUser to the port driver for the portName,addr. The port driver may or may not be connected to the actual device. Thus, connectDevice and asynCommon:connect are completely different.

See the Theory of Operation section for a description of the difference between single and multi-device port drivers.

disconnect Disconnect the asynUser from the port,addr to which it is connected via a previous call to connectDevice. The call will fail if the asynUser is queued or locked, or has a callback registered via exceptionCallbackAdd. Note that asynManager:disconnect and asynCommon:disconnect are completely different.
exceptionCallbackAdd Callback will be called whenever one of the exceptions defined by asynException occurs. The callback can call isConnected, isEnabled, or isAutoConnect to find the connection state. asynTrace provides methods to find out the current trace settings.
exceptionCallbackRemove Callback is removed. This must be called before disconnect.
findInterface Find a driver interface. If interposeInterfaceOK is true, then findInterface returns the last interface registered or interposed. Otherwise, the interface registered by registerPort is returned. It returns 0 if the interfaceType is not supported.

The user needs the address of the driver's interface and of pdrvPvt so that calls can be made to the driver. For example:

asynInterface *pasynInterface;
asynOctet *pasynOctet;
void *pasynOctetPvt;
...
pasynInterface = pasynManager->findInterface(
        pasynUser,asynOctetType,1);
if(!pasynInterface) { /*error do something*/}
pasynOctet = (asynOctet *)pasynInterface->pinterface;
pasynOctetPvt = pasynInterface->pdrvPvt;
...
/* The following call must be made from a callback */
pasynOctet->read(pasynOctetPvt,pasynUser,...
        
queueRequest

When registerPort is called, the caller must specify if it can block, i.e. attribute bit ASYN_CANBLOCK is set or cleared. If the port has been registered with ASYN_CANBLOCK true then the request is put on a queue for the thread associated with the queue. If the port has been registered with ASYN_CANBLOCK false then queueRequest locks the port and calls the process callback. In either case the process callback specified in the call to createAsynUser is called.

If the asynUser is already on a queue, asynError is returned. The timeout starts when the request is queued. A value less than or equal to 0.0 means no timeout. The request is removed from the queue before the callback is called. Callbacks are allowed to make requests to asynManager such as queueRequest, blockProcessCallback, etc. It is even permissible to call freeAsynUser from a callback but the request will be delayed until after the callback completes.

The priority asynQueuePriorityConnect must be used for asynCommon:connect and asynCommon:disconnect calls, and must NOT be used for any other calls.

If a timeout callback was not passed to createAsynUser and a queueRequest with a non-zero timeout is requested, the request fails.

Attempts to queue a request other than a connection request to a disconnected port will fail unless the reason is ASYN_REASON_QUEUE_EVEN_IF_NOT_CONNECTED.

cancelRequest If a asynUser is queued, remove it from the queue. If either the process or timeout callback is active when cancelRequest is called than cancelRequest will not return until the callback completes.
blockProcessCallback

unblockProcessCallback

blockProcessCallback is a request to prevent acccess to a device or port by other asynUsers between queueRequests. blockProcessCallback can be called from a processCallback or when the asynUser has no request queued. When called from processCallback blocking starts immediately, otherwise blocking starts the next time processCallback is called. Blocking means that no other asynUser's processCallback will be called until unblockProcessCallback is called. Note the following restrictions for blockProcessCallback:
  • blockProcessCallback only works with drivers that can block and an error is returned if it is called for non-blocking drivers.
  • queueRequests that specify a priority of asynQueuePriorityConnect are not blocked.
It is permissible to simultaneously block allDevices and also the device to which the asynUser is connected.
lockPort/unlockPort Lock access to a port driver. This is used by code that is willing to block while making calls to a port driver. The code can call lockPort, make an arbitrary number of calls to the port driver, and than call unlockPort. Other code that calls queueRequest and/or lockPort will be delayed between the calls to lockPort and unlockPort.
queueLockPort/queueUnlockPort Lock access to a port driver. This is used by code that is willing to block while making calls to a port driver. The code can call lockPort, make an arbitrary number of calls to the port driver, and than call unlockPort. Other code that calls queueRequest and/or lockPort will be delayed between the calls to lockPort and unlockPort. The difference between lockPort and queueLockPort is that queueLockPort queues a request to lock the port, using the same queues as queueRequest. This means that a thread that repeatedly calls queueLockPort without sleeping between calls will still allow other threads to access the port. This is not true with lockPort, which will take a mutex as soon as the port is free, and can prevent other threads from accessing the port at all.
canBlock yesNo is set to (0,1), i.e. (false,true) if calls to the low level driver can block. The value is determined by the attributes passed to registerPort.
getAddr *addr is set equal to the address which the user specified in the call to connectDevice or -1 if the port does not support multiple devices.

See the Theory of Operation section for a description of the difference between single and multi-device port drivers.

getPortName *pportName is set equal to the name of the port to which the user is connected.
registerPort This method is called by drivers. A call is made for each port instance. Attributes is a set of bits. Currently two bits are defined: ASYN_MULTIDEVICE and ASYN_CANBLOCK. The driver must specify these properly. autoConnect, which is (0,1) for (no,yes), provides the initial value for the port and all devices connected to the port. priority and stacksize are only relevant if ASYN_CANBLOCK=1, in which case asynManager uses these values when it creates the port thread with epicsThreadCreate(). If priority is 0, then the default value epicsThreadPriorityMedium will be assigned. If stackSize is 0, the default value of epicsThreadGetStackSize(epicsThreadStackMedium) will be assigned. The portName argument specifies the name by which the upper levels of the asyn code will refer to this communication interface instance. The registerPort method makes an internal copy of the string to which the name argument points.
registerInterface This is called by port drivers for each supported interface. This method does not make a copy of the asynInterface to which the pasynInterface argument points. Callers must store the asynInteface in a location which is retained for the lifetime of the port. This is commonly done by placing the asynInterface structure in the 'driver private' structure.
exceptionConnect This method must be called by the driver when and only when it connects to a port or device.
exceptionDisconnect This method must be called by the driver when and only when it disconnects from a port or device.
interposeInterface This is called by a software layer between client code and the port driver. For example, if a device echos writes then a software module that issues a read after each write could be created and call interposeInterface for interface asynOctet.

Multiple interposeInterface calls for a port/addr/interface can be issued. *ppPrev is set to the address of the previous asynInterface. Thus the software module that last called interposeInterface is called by user code. It in turn can call the software module that was the second to last to call interposeInterface. This continues until the actual port driver is called.

interposeInterface can also be called with an asynInterface that has not been previously registered or replaced. In this case *ppPrev will be null. Thus, new interfaces that are unknown to the low level driver can be implemented.

enable If enable is set yes, then queueRequests are not dequeued unless their queue timeout occurs.
autoConnect If autoConnect is true and the port or device is not connected when a user callback is scheduled to be called, asynManager calls pasynCommon->connect. See the discussion of Flow of Control below for details.
isConnected *yesNo is set to (0,1) if the port or device (is not, is) connected.
isEnabled *yesNo is set to (0,1) if the port or device (is not, is) enabled.
isAutoConnect *yesNo is set to (0,1) if the portThread (will not, will) autoConnect for the port or device.
setAutoConnectTimeout Changes the timeout when waiting for the initial connection callback from port drivers. This callback occurs in response to asynManager queueing a connection request, which happens when the port driver registers its asynCommon interface. The default timeout is 0.5 seconds.
waitConnect Wait for up to timeout seconds for the port/device to connect.
registerInterruptSource If a low level driver supports interrupts it must call this for each interface that supports interrupts. pasynPvt must be the address of a void * that will be given a value by registerInterruptSource. This argument is passed interruptStart and interruptEnd.
getInterruptPvt Any code that wants to call createInterruptNode but does not know the adresss of pasynPvt can find it via this method. The caller must be connected to a device, i.e. must have called connectDevice. If the caller is not connected, getInterruptPvt returns asynError.
createInterruptNode

freeInterruptNode

These methods are the only way a user can allocate and free an interruptNode. pasynPvt is the value obtained from getInterruptPvt. createInterruptNode/freeInterruptNode are separate methods rather than being done automatically by addInterruptUser/removeInterruptUser so that addInterruptUser/removeInterruptUser can be efficient.
addInterruptUser

removeInterruptUser

Code that implements registerInterruptUser/cancelInterruptUser must call addInterruptUser/removeInterruptUser to add and remove users from the list or else calls to interruptStart/interruptEnd will not work. This is an efficient operation so that a user can repeatedly call registerInterruptUser/cancelInterruptUser. If either of these is called while a interrupt is being processed, i.e. between calls to interruptStart/interruptEnd, the call will block until interruptEnd is called. The process callback for the asynUser specified in the call to addInterruptUser must not call removeInterruptUser or it will block forever.
interruptStart

interruptEnd

The code that implements interrupts is interface dependent. The only service asynManager provides is a thread-safe implemention of the user list. When the code wants to call the callback specified in the calls to registerInterruptUser, it calls interruptStart to obtain the list of callbacks. When it is done it calls interruptEnd. If any requests are made to addInterruptUser/removeInterruptUser between the calls to interruptStart and interruptEnd, asynManager delays the requests until interruptEnd is called.
registerTimeStampSource Registers a user-defined time stamp callback function.
unregisterTimeStampSource Unregisters any user-defined timestamp callback function and reverts to the default timestamp source function in asynManager, which simply calls epicsTimeGetCurrent().
updateTimeStamp Set the current time stamp for this port by calling either the default timestamp source, or a user-defined timestamp source that was registered with registerTimeStampSource.
getTimeStamp Get the current time stamp for this port that was returned by the most recent call to updateTimeStamp.
setTimeStamp Set the current time stamp for this port directly from the timestamp value passed to this function.
strStatus Returns a descriptive string corresponding to the asynStatus value.

asynCommon

asynCommon describes the methods that must be implemented by drivers.

/* Device Interface supported by ALL asyn drivers*/
#define asynCommonType "asynCommon"
typedef struct  asynCommon {
    void       (*report)(void *drvPvt,FILE *fp,int details);
    /*following are to connect/disconnect to/from hardware*/
    asynStatus (*connect)(void *drvPvt,asynUser *pasynUser);
    asynStatus (*disconnect)(void *drvPvt,asynUser *pasynUser);
}asynCommon;
asynCommon
report Generates a report about the hardware device. This is the only asynCommon method that does not have to be called by the queueRequest callback or between calls to lockPort/unlockPort.
connect Connect to the hardware device or communication path. The queueRequest must specify priority asynQueuePriorityConnect.
disconnect Disconnect from the hardware device or communication path. The queueRequest must specify priority asynQueuePriorityConnect.

asynCommonSyncIO

asynCommonSyncIO provides a convenient interface for software that needs to perform "synchronous" operations to an asyn device, i.e. that blocks while waiting for the port to be available and for the operation to complete. The code does not need to handle callbacks or understand the details of the asynManager and asynCommon interfaces.

typedef struct asynCommonSyncIO {
    asynStatus (*connect)(const char *port, int addr, 
                          asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*connectDevice)(asynUser *pasynUser);
    asynStatus (*disconnectDevice)(asynUser *pasynUser);
    asynStatus (*report)(asynUser *pasynUser, FILE *fd, int details);
} asynCommonSyncIO;
epicsShareExtern asynCommonSyncIO *pasynCommonSyncIO;

Note that there is a potential for confusion in the connect* and disconnect* function names of this interface. For consistency with the other SyncIO interfaces, connect calls pasynManager->connectDevice, disconnect calls pasynManager->disconnect, connectDevice calls asynCommon->connect, and disconnectDevice calls asynCommon->disconnect.

asynDrvUser

asynDrvUser provides methods that allow an asynUser to communicate user specific information to/from a port driver

#define asynDrvUserType "asynDrvUser"
typedef struct  asynDrvUser {
    /*The following do not have to be called via queueRequest callback*/
    asynStatus (*create)(void *drvPvt,asynUser *pasynUser,
        const char *drvInfo, const char **pptypeName,size_t *psize);
    asynStatus (*getType)(void *drvPvt,asynUser *pasynUser,
        const char **pptypeName,size_t *psize);
    asynStatus (*destroy)(void *drvPvt,asynUser *pasynUser);
}asynDrvUser;
asynDrvUser
create The user, i.e. device support calls create. The driver can create any resources it needs. It can use pasynUser->drvUser to provide access to the resources. If the asynUser and the driver both know how to access the resources they must agree about the name for the resource and a size. If pptypeName is not null the driver can give a value to *pptypeName. If psize is not null the driver can give a value to *psize. Unless asynUser receives a typeName and size that it recognizes it must not access asynUser.drvUser.
getType If other code, e.g. an interposeInterface wants to access asynUser.drvUser it must call this and verify that typeName and size are what it expects.
destroy Destroy the resources created by create and set asynUser.drvUser null.

asynLockPortNotify

This is provided for port drivers that are an asynUser of another port driver. For example a serial bus driver can be implemented by connecting to a standard serial port to perform the actual I/O. When the serial bus port is locked, either by the requester calling lockPort or because a queueRequest was dequeued, then the serial bus driver needs to lock the associated serial port.

The serial bus driver registers interface asynLockPortNotify. Whenever the serial bus port is locked, asynManager calls pasynLockPortNotify.lock. The serial bus driver calls asynManager.lockPort for the serial port to which it is connected. Similarly for unlockPort. Thus while the serial bus port is locked, the serial bus is also locked.

asynLockPortNotify is used only by asynManager itself. It is not put in the list of interfaces for the port.

asynLockPortNotify is:

#define asynLockPortNotifyType "asynLockPortNotify"
typedef struct  asynLockPortNotify {
    asynStatus (*lock)(void *drvPvt,asynUser *pasynUser);
    asynStatus (*unlock)(void *drvPvt,asynUser *pasynUser);
}asynLockPortNotify;
asynLockPortNotify
lock Called when asynManager.lockPort is called. The driver normally calls asynManager.lockPort for the port to which it is connected.
unlock Called when asynManager.unlockPort is called. The driver normally calls asynManager.unlockPort for the port to which it is connected.

asynOption

asynOption provides a generic way of setting driver specific options. For example the serial port driver uses this to specify baud rate, stop bits, etc.

#define asynOptionType "asynOption"
/*The following are generic methods to set/get device options*/
typedef struct asynOption {
    asynStatus (*setOption)(void *drvPvt, asynUser *pasynUser,
                                const char *key, const char *val);
    asynStatus (*getOption)(void *drvPvt, asynUser *pasynUser,
                                const char *key, char *val, int sizeval);
}asynOption;
asynOption
setOption Set value associated with key.
getOption Get value associated with key.

Trace Interface

/*asynTrace is implemented by asynManager*/
/*All asynTrace methods can be called from any thread*/
/* traceMask definitions*/
#define ASYN_TRACE_ERROR     0x0001
#define ASYN_TRACEIO_DEVICE  0x0002
#define ASYN_TRACEIO_FILTER  0x0004
#define ASYN_TRACEIO_DRIVER  0x0008
#define ASYN_TRACE_FLOW      0x0010
#define ASYN_TRACE_WARNING   0x0020

/* traceIO mask definitions*/
#define ASYN_TRACEIO_NODATA 0x0000
#define ASYN_TRACEIO_ASCII  0x0001
#define ASYN_TRACEIO_ESCAPE 0x0002
#define ASYN_TRACEIO_HEX    0x0004

/* traceInfo mask definitions*/
#define ASYN_TRACEINFO_TIME 0x0001
#define ASYN_TRACEINFO_PORT 0x0002
#define ASYN_TRACEINFO_SOURCE 0x0004
#define ASYN_TRACEINFO_THREAD 0x0008

/* asynPrint and asynPrintIO are macros that act like
   int asynPrintSource(asynUser *pasynUser,int reason, __FILE__, __LINE__, const char *format, ... );
   int asynPrintIOSource(asynUser *pasynUser,int reason,
        const char *buffer, size_t len, __FILE__, __LINE__, const char *format, ... );
*/
typedef struct asynTrace {
    /* lock/unlock are only necessary if caller performs I/O other than */
    /* by calling asynTrace methods                                     */
    asynStatus (*lock)(asynUser *pasynUser);
    asynStatus (*unlock)(asynUser *pasynUser);
    asynStatus (*setTraceMask)(asynUser *pasynUser,int mask);
    int        (*getTraceMask)(asynUser *pasynUser);
    asynStatus (*setTraceIOMask)(asynUser *pasynUser,int mask);
    int        (*getTraceIOMask)(asynUser *pasynUser);
    asynStatus (*setTraceInfoMask)(asynUser *pasynUser,int mask);
    int        (*getTraceInfoMask)(asynUser *pasynUser);
    asynStatus (*setTraceFile)(asynUser *pasynUser,FILE *fp);
    FILE       *(*getTraceFile)(asynUser *pasynUser);
    asynStatus (*setTraceIOTruncateSize)(asynUser *pasynUser,size_t size);
    size_t     (*getTraceIOTruncateSize)(asynUser *pasynUser);
#if defined(__GNUC__) && (__GNUC__ < 3)
    /* GCC 2.95 does not allow EPICS_PRINTF_STYLE on function pointers */
    int        (*print)(asynUser *pasynUser,int reason, const char *pformat, ...);
    int        (*printSource)(asynUser *pasynUser,int reason, const char *fileName, int line, const char *pformat, ...);
    int        (*vprint)(asynUser *pasynUser,int reason, const char *pformat, va_list pvar);
    int        (*vprintSource)(asynUser *pasynUser,int reason, const char *file, int line, const char *pformat, va_list pvar);
    int        (*printIO)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *pformat, ...);
    int        (*printIOSource)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *file, int line, const char *pformat, ...);
    int        (*vprintIO)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *pformat, va_list pvar);
    int        (*vprintIOSource)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *file, int line, const char *pformat, va_list pvar);
#else
    int        (*print)(asynUser *pasynUser,int reason, const char *pformat, ...) EPICS_PRINTF_STYLE(3,4);
    int        (*printSource)(asynUser *pasynUser,int reason, const char *fileName, int line, const char *pformat, ...) EPICS_PRINTF_STYLE(5,6);
    int        (*vprint)(asynUser *pasynUser,int reason, const char *pformat, va_list pvar) EPICS_PRINTF_STYLE(3,0);
    int        (*vprintSource)(asynUser *pasynUser,int reason, const char *file, int line, const char *pformat, va_list pvar) EPICS_PRINTF_STYLE(5,0);
    int        (*printIO)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *pformat, ...) EPICS_PRINTF_STYLE(5,6);
    int        (*printIOSource)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *file, int line, const char *pformat, ...) EPICS_PRINTF_STYLE(7,8);
    int        (*vprintIO)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *pformat, va_list pvar) EPICS_PRINTF_STYLE(5,0);
    int        (*vprintIOSource)(asynUser *pasynUser,int reason,
                    const char *buffer, size_t len,const char *file, int line, const char *pformat, va_list pvar) EPICS_PRINTF_STYLE(7,0);
#endif
}asynTrace;
epicsShareExtern asynTrace *pasynTrace;

asynTrace

asynDriver provides a trace facility with the following attributes:

In order for the trace facility to perform properly; device support and all drivers must use the trace facility. Device and driver support can directly call the asynTrace methods. The asynPrint and asynPrintIO macros are provided so that it is easier for device/driver support. Support can have calls like:

    asynPrint(pasynUser,ASYN_TRACE_FLOW,"%s Calling queueRequest\n",
        someName);

The asynPrintIO call is designed for device support or drivers that issue read or write requests. They make calls like:

    asynPrintIO(pasynUser,ASYN_TRACEIO_DRIVER,data,nchars,"%s nchars %d",
                someName,nchars);

The asynTrace methods are implemented by asynManager. These methods can be used by any code that has created an asynUser and is connected to a device. All methods can be called by any thread. That is, an application thread and/or a portThread. If a thread performs all I/O via calls to print or printIO, then it does not have to call lock or unlock. If it does want to do its own I/O, it must lock before any I/O and unlock after. For example:

    pasynTrace->lock(pasynUser);
    fd = pasynTrace->getTraceFile(pasynUser);
    /*perform I/O to fd */
    pasynTrace->unlock(pasynUser);

If the asynUser is not connected to a port, i.e. pasynManager->connectDevice has not been called, then a "global" device is assumed. This is useful when asynPrint is called before connectDevice.

asynTrace
lock/unlock These are only needed for code that call asynTrace.print or asynTrace.printIO instead of asynPrint and asynPrintIO.

print, and printIO both lock while performing their operations. The get methods do not lock (except for getTraceFile) and they are safe. Except for setTraceFile the set methods do not block, since worst that can happen is that the user gets a little more or a little less output.

setTraceMask Set the trace mask. Normally set by the user requesting it via a shell command or the devTrace device support. Setting the trace mask for a port also sets the trace mask for all devices connected to that port
getTraceMask Get the trace mask. Device support that wants to issue trace messages calls this to see what trace options have been requested.
setTraceIOMask Set the traceIO mask. Normally set by the user requesting it via a shell command or the devTrace device support. Setting the traceIO mask for a port also sets the traceIO mask for all devices connected to that port
getTraceIOMask Get the traceIO mask. Support that wants to issue its own IO messages instead of calling asynPrintIO should call this and honor the mask settings. Most code will not need it.
setTraceInfoMask Set the traceInfo mask. Normally set by the user requesting it via a shell command or the devTrace device support. Setting the traceInfo mask for a port also sets the traceInfo mask for all devices connected to that port
getTraceInfoMask Get the traceInfo mask. Support that wants to issue its own IO messages instead of calling asynPrint should call this and honor the mask settings. Most code will not need it.
setTraceFile Set the stream to use for output. A NULL argument means use errlog. Normally set by the user requesting it via a shell command or by the devTrace device support. If the current output stream is none of (NULL, stdout, stderr) then the current output stream is closed before the new stream is used.
getTraceFile Get the file descriptor to use for output. Device support that wants to issue its own IO messages instead of calling asynPrintIO should call this and honor the mask settings. In this case, lock must have been called first. Most code will not need it. If the return value is 0, then ouput should be directed to errlog.
setTraceIOTruncateSize Determines how much data is printed by printIO. In all cases it determines how many bytes of the buffer are displayed. The actual number of characters printed depends on the traceIO mask. For example ASYN_TRACEIO_HEX results in 3 characters being printed for each byte. Normally set by the user requesting it via a shell command or the devTrace device support.
getTraceIOTruncateSize Get the current truncate size. Called by asynPrintIO. Code that does its own I/O should also support the traceIO mask.
print If reason ORed with the current traceMask is not zero, then the message is printed. This method is provided for backwards compatibility. The asynPrint macro now calls printSource().
printSource If reason ORed with the current traceMask is not zero, then the message is printed. Most code should call asynPrint instead of calling this method. This method is the same as print() but with the additional file and line arguments.
vprint This is the same as print, but using a va_list as its final argument.
vprintSource This is the same as printSource, but using a va_list as its final argument.
printIO If reason ORed with the current traceMask is not zero then the message is printed. If len is >0, then the buffer is printed using the traceIO mask and getTraceIOTruncateSize. This method is provided for backwards compatibility. The asynPrintIO macro now calls printIOSource().
printIOSource If reason ORed with the current traceMask is not zero then the message is printed. If len is >0, then the buffer is printed using the traceIO mask and getTraceIOTruncateSize. Most code should call asynPrintIO instead of calling this method. This method is the same as printIO() but with the additional file and line arguments.
vprintIO This is the same as printIO, but using a va_list as its final argument.
vprintIOSource This is the same as printIOSource, but using a va_list as its final argument.

Standard Message Based Interfaces

These are interfaces for communicating with message based devices, where message based means that the device communicates via octet strings, i.e. arrays of 8 bit bytes. Three interfaces are provided: asynOctet, asynOctetBase, and asynOctetSyncIO. asynOctet is generic message based interface. asynOctetBase is an interface used by port drivers that implement asynOctet. It's primary purpose is to help with interrupt support. asynOctetSyncIO provides a synchronous inteface to asynOctet and can be used by code that is willing to block.

asynOctet

asynOctet describes the methods implemented by drivers that use octet strings for sending commands and receiving responses from a device.

NOTE: The name octet is used instead of ASCII because it implies that communication is done via 8-bit bytes.

#define ASYN_EOM_CNT 0x0001 /*Request count reached*/
#define ASYN_EOM_EOS 0x0002 /*End of String detected*/
#define ASYN_EOM_END 0x0004 /*End indicator detected*/

typedef void (*interruptCallbackOctet)(void *userPvt, asynUser *pasynUser,
              char *data,size_t numchars, int eomReason);

typedef struct asynOctetInterrupt {
    asynUser *pasynUser;
    int      addr;
    interruptCallbackOctet callback;
    void *userPvt;
}asynOctetInterrupt;


#define asynOctetType "asynOctet"
typedef struct asynOctet{
    asynStatus (*write)(void *drvPvt,asynUser *pasynUser,
                    const char *data,size_t numchars,size_t *nbytesTransfered);
    asynStatus (*read)(void *drvPvt,asynUser *pasynUser,
                    char *data,size_t maxchars,size_t *nbytesTransfered,
                    int *eomReason);
    asynStatus (*flush)(void *drvPvt,asynUser *pasynUser);
    asynStatus (*registerInterruptUser)(void *drvPvt,asynUser *pasynUser,
                    interruptCallbackOctet callback, void *userPvt,
                    void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
    asynStatus (*setInputEos)(void *drvPvt,asynUser *pasynUser,
                    const char *eos,int eoslen);
    asynStatus (*getInputEos)(void *drvPvt,asynUser *pasynUser,
                    char *eos, int eossize, int *eoslen);
    asynStatus (*setOutputEos)(void *drvPvt,asynUser *pasynUser,
                    const char *eos,int eoslen);
    asynStatus (*getOutputEos)(void *drvPvt,asynUser *pasynUser,
                    char *eos, int eossize, int *eoslen);
}asynOctet;
/* asynOctetBase does the following:
   calls  registerInterface for asynOctet.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynOctetBaseType "asynOctetBase"
typedef struct asynOctetBase {
    asynStatus (*initialize)(const char *portName,
        asynDriverasynInterface *pasynOctetInterface,
        int processEosIn,int processEosOut,int interruptProcess);
    void       (*callInterruptUsers)(asynUser *pasynUser,void *pasynPvt,
        char *data,size_t *nbytesTransfered,int *eomReason);
} asynOctetBase;
epicsShareExtern asynOctetBase *pasynOctetBase;

asynOctet
write Send a message to the device. *nbytesTransfered is the number of 8-bit bytes sent to the device. Interpose or driver code may add end of string terminators to the message but the extra characters are not included in *nbytesTransfered.
read Read a message from the device. *nbytesTransfered is the number of 8-bit bytes read from the device. If read returns asynSuccess than eomReason ( some combination of ASYN_EOM_CNT, ASYN_EOM_EOS, and ASYN_EOM_END)tells why the read completed. Interpose or driver code may strip end of string terminators from the message. If it does the first eos character will be replaced by null and the eos characters will not be included in nbytesTransfered.
flush Flush the input buffer.
registerInterruptUser Register a user that will be called whenever a new message is received. NOTE: The callback must not block and must not call registerInterruptUser or cancelInterruptUser.
cancelInterruptUser Cancel a registered user.
setInputEos Set End Of String for input. For example "\n". Note that gpib drivers usually accept at most a one character terminator.
getInputEos Get the current End of String.
setOutputEos Set End Of String for output.
getOutputEos Get the current End of String.

asynOctetBase is an interface and implementation for drivers that implement interface asynOctet. asynOctetBase implements registerInterruptUser and cancelInterruptUser.

For single device support, it can optionally implement interrupt support. A driver that implements interrupts must call registerInterruptSource. If it asks asynOctetBase to handle interrupts it calls asynOctetBase:callInterruptUsers when it has new data.

For single device support asynOctetBase can optionally call asynInterposeEosConfig to handle end of string processing for input and/or output.

Any null method in the interface passed to initialize are replaced by a method supplied by asynOctetBase.

For an example of how to use asynOctetBase look at asyn/testApp/src/echoDriver.c

asynOctetBase
initialize After a driver calls registerPort it can call:
pasynOctetBase->initialize(...
Any null methods in the asynInterface are replaced by default implementations. If the port is not multi-device and either processEosIn or processEosOut is specified, asynInterposeEosConfig is called. If the port is not multi-device and interruptProcess is specified, then whenever read is called, asynBase calls all the registered interrupt users. asynOctetBase can not implement processEosIn, processEosOut, and interruptProcess if the port is a multi-device port. Since this method is called only during initialization it can be called directly rather than via queueRequest.
callInterruptUsers Calls the callbacks registered via registerInterruptUser.

asynOctetSyncIO

asynOctetSyncIO provides a convenient interface for software that needs to perform "synchronous" I/O to an asyn device, i.e. that starts an I/O operation and then blocks while waiting for the response. The code does not need to handle callbacks or understand the details of the asynManager and asynOctet interfaces. Examples include motor drivers running in their own threads, SNL programs, and the shell commands described later in this document.

typedef struct asynOctetSyncIO {
   asynStatus (*connect)(const char *port, int addr,
                         asynUser **ppasynUser, const char *drvInfo);
   asynStatus (*disconnect)(asynUser *pasynUser);
   asynStatus (*write)(asynUser *pasynUser,
                  char const *buffer, size_t buffer_len,
                  double timeout,size_t *nbytesTransfered);
   asynStatus (*read)(asynUser *pasynUser, char *buffer, size_t buffer_len,
                  double timeout, size_t *nbytesTransfered,int *eomReason);
   asynStatus (*writeRead)(asynUser *pasynUser,
                  const char *write_buffer, size_t write_buffer_len,
                  char *read_buffer, size_t read_buffer_len,
                  double timeout,
                  size_t *nbytesOut, size_t *nbytesIn, int *eomReason);
   asynStatus (*flush)(asynUser *pasynUser);
   asynStatus (*setInputEos)(asynUser *pasynUser,
                  const char *eos,int eoslen);
   asynStatus (*getInputEos)(asynUser *pasynUser,
                  char *eos, int eossize, int *eoslen);
   asynStatus (*setOutputEos)(asynUser *pasynUser,
                  const char *eos,int eoslen);
   asynStatus (*getOutputEos)(asynUser *pasynUser,
                  char *eos, int eossize, int *eoslen);
   asynStatus (*writeOnce)(const char *port, int addr,
                  char const *buffer, size_t buffer_len, double timeout,
                  size_t *nbytesTransfered, const char *drvInfo);
   asynStatus (*readOnce)(const char *port, int addr,
                  char *buffer, size_t buffer_len, double timeout,
                  size_t *nbytesTransfered,int *eomReason, const char *drvInfo);
   asynStatus (*writeReadOnce)(const char *port, int addr,
                  const char *write_buffer, size_t write_buffer_len,
                  char *read_buffer, size_t read_buffer_len,
                  double timeout,
                  size_t *nbytesOut, size_t *nbytesIn, int *eomReason,
                  const char *drvInfo);
   asynStatus (*flushOnce)(const char *port, int addr,const char *drvInfo);
   asynStatus (*setInputEosOnce)(const char *port, int addr,
                  const char *eos,int eoslen,const char *drvInfo);
   asynStatus (*getInputEosOnce)(const char *port, int addr,
                  char *eos, int eossize, int *eoslen,const char *drvInfo);
   asynStatus (*setOutputEosOnce)(const char *port, int addr,
                  const char *eos,int eoslen,const char *drvInfo);
   asynStatus (*getOutputEosOnce)(const char *port, int addr,
                  char *eos, int eossize, int *eoslen,const char *drvInfo);
} asynOctetSyncIO;
epicsShareExtern asynOctetSyncIO *pasynOctetSyncIO;
asynOctetSyncIO
connect Connects to an asyn port and address, returns a pointer to an asynUser structure.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls asynOctet->write and waits for the operation to complete or time out.
read Calls asynOctet->read. Waits for the operation to complete or time out.
writeRead Calls pasynOctet->flush, pasynOctet->write, and asynOctet->read. Waits for the operations to complete or time out.
flush Calls pasynOctet->flush
setInputEos Calls pasynOctet->setInputEos
getInputEos Calls pasynOctet->getInputEos
setOutputEos Calls pasynOctet->setOutputEos
getOutputEos Calls pasynOctet->getOutputEos
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.
readOnce This does a connect, read, and disconnect.
writeReadOnce This does a connect, writeRead, and disconnect.

End of String Support

asynOctet provides methods for handling end of string (message) processing. It does not specify policy. Device support code, interpose layers, or low level drivers can all handle EOS processing. An application developer must decide what policy will be followed for individual devices. The policy will be determined by the device, the device support, and the driver.


Standard Register Based Interfaces

Introduction

This section descibes interfaces for register based devices. Support is provided for:

Note that hardware may have registers with smaller sizes, e.g. 16 bit registers. The standard interfaces can still be used by setting the unused bits to 0.

For all of these interfaces a default implementation and a synchronous inplementation are provided. Lets use Int32 as an example.

addr - What does it mean for register based interfaces?

Low level register based drivers are normally multi-device. The meaning of addr is:

Example Drivers

Two examples of drivers that might implement and use the interfaces are:

asynInt32

asynInt32 describes the methods implemented by drivers that use integers for communicating with a device.

typedef void (*interruptCallbackInt32)(void *userPvt, asynUser *pasynUser, 
                                       epicsInt32 data);
typedef struct asynInt32Interrupt {
    int addr;
    asynUser *pasynUser;
    interruptCallbackInt32 callback;
    void *userPvt;
} asynInt32Interrupt;
#define asynInt32Type "asynInt32"
typedef struct asynInt32 {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser, epicsInt32 value);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser, epicsInt32 *value);
    asynStatus (*getBounds)(void *drvPvt, asynUser *pasynUser,
                           epicsInt32 *low, epicsInt32 *high);
    asynStatus (*registerInterruptUser)(void *drvPvt,asynUser *pasynUser,
                           interruptCallbackInt32 callback, void *userPvt,
                           void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
} asynInt32;

/* asynInt32Base does the following:
   calls  registerInterface for asynInt32.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynInt32BaseType "asynInt32Base"
typedef struct asynInt32Base {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pint32Interface);
} asynInt32Base;
epicsShareExtern asynInt32Base *pasynInt32Base;
asynInt32
write Write an integer value to the device.
read Read an integer value from the device.
getBounds Get the bounds. For example a 16 bit ADC might set low=-32768 and high = 32767.
registerInterruptUser Registers a callback that will be called whenever new data is available. Since it can be called directly rather than via a queueRequest this method must not block.
cancelInterruptUser Cancels the callback. Since it can be called directly rather than via a queueRequest this method must not block.

asynInt32Base is an interface and associated code that is used by drivers that implement interface asynInt32. asynInt32Base provides code to handle registerInterruptUser/cancelInterruptUser. The driver must itself call the callbacks via calls to asynManager:interruptStart and asynManager:interruptEnd.

asynInt32Base
initialize After a driver calls registerPort it can call:
pasynInt32Base->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynInt32
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
getBounds Reports an error "getBounds is not supported" and returns asynError
registerInterruptUser registers an interrupt callback.
cancelInterruptUser Cancels the callback

asynInt32SyncIO

asynInt32SyncIO describes a synchronous interface to asynInt32. The code that calls it must be willing to block.

#define asynInt32SyncIOType "asynInt32SyncIO"
typedef struct asynInt32SyncIO {
    asynStatus (*connect)(const char *port, int addr,
                          asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser, epicsInt32 value,double timeout);
    asynStatus (*read)(asynUser *pasynUser, epicsInt32 *pvalue,double timeout);
    asynStatus (*getBounds)(asynUser *pasynUser,
                    epicsInt32 *plow, epicsInt32 *phigh);
    asynStatus (*writeOnce)(const char *port, int addr,
                    epicsInt32 value,double timeout, const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr,
                    epicsInt32 *pvalue,double timeout, const char *drvInfo);
    asynStatus (*getBoundsOnce)(const char *port, int addr,
                    epicsInt32 *plow, epicsInt32 *phigh,const char *drvInfo);
} asynInt32SyncIO;
epicsShareExtern asynInt32SyncIO *pasynInt32SyncIO;
asynInt32SyncIO
connect Connects to a port and address, returns a pointer to an asynUser.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynInt32->write and waits for the operation to complete or time out.
read Calls pasynInt32->read and waits for the operation to complete or time out.
getBounds Calls pasynInt32->getBounds and waits for the operation to complete or time out.
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.
getBoundsOnce This does a connect, getBounds, and disconnect.

asynUInt32Digital

asynUInt32Digital describes the methods for communicating via bits of an Int32 register.

typedef enum {
    interruptOnZeroToOne, interruptOnOneToZero, interruptOnBoth
} interruptReason;

typedef void (*interruptCallbackUInt32Digital)(void *userPvt, 
                 asynUser *pasynUser, epicsUInt32 data);
typedef struct asynUInt32DigitalInterrupt {
    epicsUInt32 mask;
    int addr;
    asynUser *pasynUser;
    interruptCallbackUInt32Digital callback;
    void *userPvt;
} asynUInt32DigitalInterrupt;
#define asynUInt32DigitalType "asynUInt32Digital"
typedef struct asynUInt32Digital {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser,
         epicsUInt32 value, epicsUInt32 mask);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser,
        epicsUInt32 *value, epicsUInt32 mask);
    asynStatus (*setInterrupt)(void *drvPvt, asynUser *pasynUser,
        epicsUInt32 mask, interruptReason reason);
    asynStatus (*clearInterrupt)(void *drvPvt, asynUser *pasynUser,
        epicsUInt32 mask);
    asynStatus (*getInterrupt)(void *drvPvt, asynUser *pasynUser,
        epicsUInt32 *mask, interruptReason reason);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
        interruptCallbackUInt32Digital callback,void *userPvt,epicsUInt32 mask,
        void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
} asynUInt32Digital;

/* asynUInt32DigitalBase does the following:
   calls  registerInterface for asynUInt32Digital.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynUInt32DigitalBaseType "asynUInt32DigitalBase"
typedef struct asynUInt32DigitalBase {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pasynUInt32DigitalInterface);
} asynUInt32DigitalBase;
epicsShareExtern asynUInt32DigitalBase *pasynUInt32DigitalBase;
asynUInt32Digital
write Modify the bits specified by mask with the corresponding bits in value.
read Read the bits specified by mask into value. The other bits of value will be set to 0.
setInterrupt Set the bits specified by mask to interrupt for reason.
clearInterrupt Clear the interrupt bits specified by mask.
getInterrupt Set each bit of mask that is enabled for reason.
registerInterruptUser Register a callback that will be called whenever the driver detects a change in any of the bits specified by mask. Since it can be called directly rather than via a queueRequest this method must not block.
cancelInterruptUser Cancels the registered callback. Since it can be called directly rather than via a queueRequest this method must not block.

asynUInt32DigitalBase is an interface and associated code that is used by drivers that implement interface asynUInt32Digital. asynUInt32DigitalBase provides code to implement registerInterruptUser and cancelInterruptUser.

asynUInt32DigitalBase
initialize After a driver calls registerPort it can call:
pasynUInt32DigitalBase->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynUInt32Digital
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
setInterrupt Reports an error "setInterrupt is not supported" and returns asynError
clearInterrupt Reports an error "clearInterrupt is not supported" and returns asynError
getInterrupt Reports an error "getInterrupt is not supported" and returns asynError
registerInterruptUser registers the interrupt user. The low level driver must call the registered callbacks via calls to asynManager:interruptStart and asynManager:interruptEnd.
cancelInterruptUser Cancels the callback

asynUInt32DigitalSyncIO

asynUInt32DigitalSyncIO describes a synchronous interrace to asynUInt32Digital. The code that calls it must be willing to block.

#define asynUInt32DigitalSyncIOType "asynUInt32DigitalSyncIO"
typedef struct asynUInt32DigitalSyncIO {
    asynStatus (*connect)(const char *port, int addr,
                       asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser,
                       epicsUInt32 value,epicsUInt32 mask,double timeout);
    asynStatus (*read)(asynUser *pasynUser,
                       epicsUInt32 *pvalue,epicsUInt32 mask,double timeout);
    asynStatus (*setInterrupt)(asynUser *pasynUser,
                       epicsUInt32 mask, interruptReason reason,double timeout);
    asynStatus (*clearInterrupt)(asynUser *pasynUser,
                       epicsUInt32 mask,double timeout);
    asynStatus (*getInterrupt)(asynUser *pasynUser,
                       epicsUInt32 *mask, interruptReason reason,double timeout);
    asynStatus (*writeOnce)(const char *port, int addr,
                       epicsUInt32 value,epicsUInt32 mask,double timeout,
                       const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr,
                       epicsUInt32 *pvalue,epicsUInt32 mask,double timeout,
                       const char *drvInfo);
    asynStatus (*setInterruptOnce)(const char *port, int addr,
                       epicsUInt32 mask, interruptReason reason,double timeout,
                       const char *drvInfo);
    asynStatus (*clearInterruptOnce)(const char *port, int addr,
                       epicsUInt32 mask,double timeout,const char *drvInfo);
    asynStatus (*getInterruptOnce)(const char *port, int addr,
                       epicsUInt32 *mask, interruptReason reason,double timeout,
                       const char *drvInfo);
} asynUInt32DigitalSyncIO;
epicsShareExtern asynUInt32DigitalSyncIO *pasynUInt32DigitalSyncIO;
asynUInt32DigitalSyncIO
connect Connects to a port and address, returns a pointer to an asynUser structure.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynUInt32Digital->write and waits for the operation to complete or time out.
read Calls pasynUInt32Digital->read and waits for the operation to complete or time out.
setInterrupt Calls pasynUInt32Digital->setInterrupt and waits for the operation to complete or time out.
clearInterrupt Calls pasynUInt32Digital->clearInterrupt and waits for the operation to complete or time out.
getInterrupt Calls pasynUInt32Digital->getInterrupt and waits for the operation to complete or time out.
writeOnce,...,getInterruptOnce Does a connect, (write,...,getInterrupt), and disconnect.

asynFloat64

asynFloat64 describes the methods for communicating via IEEE double precision float values.

typedef void (*interruptCallbackFloat64)(void *userPvt, asynUser *pasynUser,
            epicsFloat64 data);
typedef struct asynFloat64Interrupt {
    asynUser *pasynUser;
    int addr;
    interruptCallbackFloat64 callback;
    void *userPvt;
} asynFloat64Interrupt;
#define asynFloat64Type "asynFloat64"
typedef struct asynFloat64 {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser, epicsFloat64 value);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser, epicsFloat64 *value);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
        interruptCallbackFloat64 callback, void *userPvt,void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
} asynFloat64;

/* asynFloat64Base does the following:
   calls  registerInterface for asynFloat64.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynFloat64BaseType "asynFloat64Base"
typedef struct asynFloat64Base {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pasynFloat64Interface);
} asynFloat64Base;
epicsShareExtern asynFloat64Base *pasynFloat64Base;
asynFloat64
write Write a value.
read Read a value.
registerInterruptUser Register a callback that is called whenever new data is available. Since it can be called directly rather than via a queueRequest this method must not block.
cancelInterruptUser Cancel the callback. Since it can be called directly rather than via a queueRequest this method must not block.
asynFloat64Base
initialize After a driver calls registerPort it can call:
pasynFloat64Base->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynFloat64
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
registerInterruptUser registers the interrupt user. The low level driver must call the registered callbacks via calls to asynManager:interruptStart and asynManager:interruptEnd.
cancelInterruptUser Cancels the callback

asynFloat64SyncIO

asynFloat64SyncIO describes a synchronous interrace to asynFloat64. The code that calls it must be willing to block.

#define asynFloat64SyncIOType "asynFloat64SyncIO"
typedef struct asynFloat64SyncIO {
    asynStatus (*connect)(const char *port, int addr,
                       asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser,epicsFloat64 value,double timeout);
    asynStatus (*read)(asynUser *pasynUser,epicsFloat64 *pvalue,double timeout);
    asynStatus (*writeOnce)(const char *port, int addr,
                       epicsFloat64 value,double timeout,const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr,
                       epicsFloat64 *pvalue,double timeout,const char *drvInfo);
} asynFloat64SyncIO;
epicsShareExtern asynFloat64SyncIO *pasynFloat64SyncIO;
asynFloat64SyncIO
connect Connects to a port and address, returns a pointer to an asynUser structure.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynFloat64->write and waits for the operation to complete or time out.
read Calls pasynFloat64->read and waits for the operation to complete or time out.
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.

asynXXXArray (where XXX is Int8, Int16, Int32, Float32 or Float64)

asynXXXArray describes the methods for communicating via 8, 16, or 32-bit integers, or 32 or 64-bit IEEE float values.

typedef void (*interruptCallbackXXXArray)(
              void *userPvt, asynUser *pasynUser,
              epicsXXX *data, size_t nelements);
typedef struct asynXXXArrayInterrupt {
    asynUser *pasynUser;
    int addr;
    interruptCallbackXXXArray callback;
    void *userPvt;
} asynXXXArrayInterrupt;
#define asynXXXArrayType "asynXXXArray"
typedef struct asynXXXArray {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser,
                       epicsXXX *value, size_t nelements);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser,
                       epicsXXX *value, size_t nelements, size_t *nIn);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
         interruptCallbackXXXArray callback,
         void *userPvt,void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
} asynXXXArray;

/* asynXXXArrayBase does the following:
   calls  registerInterface for asynXXXArray.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynXXXArrayBaseType "asynXXXArrayBase"
typedef struct asynXXXArrayBase {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pXXXArrayInterface);
} asynXXXArrayBase;
epicsShareExtern asynXXXArrayBase *pasynXXXArrayBase;
asynXXXArray
write Write an array of values.
read Read an array of values.
registerInterruptUser Register a callback that is called whenever new data is available.
cancelInterruptUser Cancel the callback

asynXXXArrayBase
initialize After a driver calls registerPort it can call:
pasynXXXArrayBase->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynXXXArrayBase
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
registerInterruptUser Registers an interrupt callback.
cancelInterruptUser Cancels the callback

asynXXXArraySyncIO

asynXXXArraySyncIO describes a synchronous interface to asynXXXArray. The code that calls it must be willing to block.

#define asynXXXArraySyncIOType "asynXXXArraySyncIO"
typedef struct asynXXXArraySyncIO {
    asynStatus (*connect)(const char *port, int addr,
                          asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser, epicsXXX *pvalue,size_t nelem,double timeout);
    asynStatus (*read)(asynUser *pasynUser, epicsXXX *pvalue,size_t nelem,size_t *nIn,double timeout);
    asynStatus (*writeOnce)(const char *port, int addr,
                    epicsXXX *pvalue,size_t nelem,double timeout, const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr,
                    epicsXXX *pvalue,size_t nelem,size_t *nIn,double timeout, const char *drvInfo);
} asynXXXArraySyncIO;
epicsShareExtern asynXXXArraySyncIO *pasynXXXArraySyncIO;
asynXXXArraySyncIO
connect Connects to a port and address, returns a pointer to an asynUser.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynXXXArray->write and waits for the operation to complete or time out.
read Calls pasynXXXArray->read and waits for the operation to complete or time out.
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.
getBoundsOnce This does a connect, getBounds, and disconnect.

asynEnum

asynEnum describes the methods implemented by drivers to define the enum strings, values, and severities for a device.

This interface is typically used by drivers to set the enum strings and values for EPICS bi, bo, mbbi, and mbbo records. The strings[] are used to define the ZNAM and ONAM fields in bi and bo records, and the ZRST, ONST, ...FFST fields in mbbi and mbbo records. The integer values[] are ignored for bi and bo records, since these always have the values of 0 and 1 corresponding to the ZNAM and ONAM states. The integer values[] are used to assign the ZRVL, ONVL, ... FFVL fields for mbbi and mbbo records. The integer severities[] are used to set the ZSV and OSV fields of bi and bo records, and the ZRSV, ONSV, ... FFSV fields of mbbi and mbbo records. The nelements parameter in the write() and read() functions is used by the client to specify the dimensions of the strings[], values[], and severities[] arrays. The driver must not access these arrays beyond element nElements-1. The nIn parameter in the read() is used by the driver to set the actual number of value enum strings, values, and severities. There is no size limitation on nElements imposed by the asynEnum interface. However, the bi and bo records limit nElements to 2, and mbbi and mbbo records limit nElements to 16. There is no size limitation on the strings imposed by the asynEnum interface. However, the string fields in the bi, bo, mbbo, and mbbi records are currently limited to 26 characters.

Clients must ensure that the char* pointers passed in strings[] in the read() function are either set to NULL or have been allocated by malloc(). The driver read() function must first call free() if a string pointer contains a non-NULL value. The driver must then allocate the strings using malloc() before copying the current enum string values to them.

typedef void (*interruptCallbackEnum)
              void *userPvt, asynUser *pasynUser,
              char *strings[], int values[], int severities[], size_t nelements);
typedef struct asynEnumInterrupt {
    asynUser *pasynUser;
    int addr;
    interruptCallbackEnum callback;
    void *userPvt;
} asynEnumInterrupt;
#define asynEnumType "asynEnum"
typedef struct asynEnum {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser,
                       char *strings[], int values[], int severities[], size_t nelements);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser,
                       char *strings[], int values[], int severities[], size_t nelements, size_t *nIn);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
             interruptCallbackEnum callback, void *userPvt,
             void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
             void *registrarPvt);
} asynEnum;

/* asynEnumBase does the following:
   calls registerInterface for asynEnum.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynEnumBaseType "asynEnumBase"
typedef struct asynEnumBase {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pEnumInterface);
} asynEnumBase;
epicsShareExtern asynEnumBase *pasynEnumBase;
asynEnum
write Writes the enum strings, enum values and enum severities to the driver.
read Reads the enum strings, enum values and enum severities to the driver.
registerInterruptUser Registers a callback that will be called whenever there are new enum strings, values and severities. Since it can be called directly rather than via a queueRequest this method must not block.
cancelInterruptUser Cancels the callback. Since it can be called directly rather than via a queueRequest this method must not block.

asynEnumBase is an interface and associated code that is used by drivers that implement interface asynEnum. asynEnumBase provides code to handle registerInterruptUser/cancelInterruptUser. The driver must itself call the callbacks via calls to asynManager:interruptStart and asynManager:interruptEnd.

asynEnumBase
initialize After a driver calls registerPort it can call:
pasynEnumBase->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynEnum
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
registerInterruptUser registers an interrupt callback.
cancelInterruptUser Cancels the callback

asynEnumSyncIO

asynEnumSyncIO describes a synchronous interface to asynEnum. The code that calls it must be willing to block.

#define asynEnumSyncIOType "asynEnumSyncIO"
typedef struct asynEnumSyncIO {
    asynStatus (*connect)(const char *port, int addr, 
                          asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser, char *strings[], int values[], int severities[], 
                       size_t nElements, double timeout);
    asynStatus (*read)(asynUser *pasynUser, char *string[], int values[],  int severities[], 
                       size_t nElements, size_t *nIn, double timeout);
    asynStatus (*writeOnce)(const char *port, int addr, char *strings[], int values[],  int severities[], 
                           size_t nElements, double timeout, const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr, char *strings[], int values[],  int severities[], 
                           size_t nElements, size_t *nIn, double timeout, const char *drvInfo);
} asynEnumSyncIO;
epicsShareExtern asynEnumSyncIO *pasynEnumSyncIO;
asynEnumSyncIO
connect Connects to a port and address, returns a pointer to an asynUser.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynEnum->write and waits for the operation to complete or time out.
read Calls pasynEnum->read and waits for the operation to complete or time out.
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.
getBoundsOnce This does a connect, getBounds, and disconnect.

asynGenericPointer

asynGenericPointer describes the methods for communicating via void* pointers. asyn clients and port drivers must agree on the type of object that is being pointed to!

typedef void (*interruptCallbackGenericPointer)(void *userPvt, asynUser *pasynUser,
            void *pdata);
typedef struct asynGenericPointerInterrupt {
    asynUser *pasynUser;
    int addr;
    interruptCallbackGenericPointer callback;
    void *userPvt;
} asynGenericPointerInterrupt;
#define asynGenericPointerType "asynGenericPointer"
typedef struct asynGenericPointer {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser, void *pvalue);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser, void *pvalue);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
        interruptCallbackGenericPointer callback, void *userPvt,void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
                    void *registrarPvt);
} asynGenericPointer;

/* asynGenericPointerBase does the following:
   calls  registerInterface for asynGenericPointer.
   Implements registerInterruptUser and cancelInterruptUser
   Provides default implementations of all methods.
   registerInterruptUser and cancelInterruptUser can be called
   directly rather than via queueRequest.
*/

#define asynGenericPointerBaseType "asynGenericPointerBase"
typedef struct asynGenericPointerBase {
    asynStatus (*initialize)(const char *portName,
                            asynInterface *pasynGenericPointerInterface);
} asynGenericPointerBase;
epicsShareExtern asynGenericPointerBase *pasynGenericPointerBase;
asynGenericPointer
write Write a value.
read Read a value.
registerInterruptUser Register a callback that is called whenever new data is available. Since it can be called directly rather than via a queueRequest this method must not block.
cancelInterruptUser Cancel the callback. Since it can be called directly rather than via a queueRequest this method must not block.

asynGenericPointerBase
initialize After a driver calls registerPort it can call:
pasynGenericPointerBase->initialize(...
Any null methods in the asynInterface are replaced by default implementations.

The default implementation of each method does the following:

asynGenericPointer
write Reports an error "write is not supported" and returns asynError
read Reports an error "read is not supported" and returns asynError
registerInterruptUser registers the interrupt user. The low level driver must call the registered callbacks via calls to asynManager:interruptStart and asynManager:interruptEnd.
cancelInterruptUser Cancels the callback

asynGenericPointerSyncIO

asynGenericPointerSyncIO describes a synchronous interrace to asynGenericPointer. The code that calls it must be willing to block.

#define asynGenericPointerSyncIOType "asynGenericPointerSyncIO"
typedef struct asynGenericPointerSyncIO {
    asynStatus (*connect)(const char *port, int addr,
                       asynUser **ppasynUser, const char *drvInfo);
    asynStatus (*disconnect)(asynUser *pasynUser);
    asynStatus (*write)(asynUser *pasynUser,void *pvalue,double timeout);
    asynStatus (*read)(asynUser *pasynUser,void *pvalue,double timeout);
    asynStatus (*writeRead)(asynUser *pasynUser,void *pwrite_buffer,void *pread_buffer,double timeout);
    asynStatus (*writeOnce)(const char *port, int addr,
                       void *pvalue,double timeout,const char *drvInfo);
    asynStatus (*readOnce)(const char *port, int addr,
                       void *pvalue,double timeout,const char *drvInfo);
    asynStatus (*writeReadOnce)(const char *port, int addr,
                       void *pwrite_buffer,void *pread_buffer,double timeout,const char *drvInfo);
} asynGenericPointerSyncIO;
epicsShareExtern asynGenericPointerSyncIO *pasynGenericPointerSyncIO;
asynGenericPointerSyncIO
connect Connects to a port and address, returns a pointer to an asynUser structure.
disconnect Disconnect. This frees all resources allocated by connect.
write Calls pasynGenericPointer->write and waits for the operation to complete or time out.
read Calls pasynGenericPointer->read and waits for the operation to complete or time out.
writeRead Calls pasynGenericPointer->write, then pasynGenericPointer->read. Waits for the operations to complete or time out.
writeOnce This does a connect, write, and disconnect.
readOnce This does a connect, read, and disconnect.
writeReadOnce This does a connect, writeRead, and disconnect.

asynStandardInterfacesBase

asynStandardInterfacesBase is an interface designed as a convenience to minimize the amount of code that must be written in the initialization routine of a port driver that uses the standard asyn message-based or register-based interfaces that are described above. Without asynStandardInterfacesBase a port driver needs to call asynRegisterInterface(), and possibly asynRegisterInterruptSource() for each interface that it supports, and handle any errors that may occur in these calls. It also needs to explicitly include several fields in its drvPvt structure for each interface. asynStandardInterfacesBase provides an interface that allows port drivers to include a single structure in its drvPvt structure, and define values in this structure. It then calls a single function to register all interfaces that it supports, and to register itself as an interrupt source on one or more of those interfaces. This can reduce the number of lines of code in the driver initialization routine by a factor of four or more.

asynStandardInterfaces structure

The following is the definition of the asynStandardInterfaces structure. Drivers will normally have a structure of this type contained in their drvPvt structure. If this structure is initialized to all zeros when drvPvt is created, then all that is necessary is to fill in the addresses of each of each of the supported interfaces (in that interface's .pinterface field), and to set the CanInterrupt flag to 1 for those interfaces that are interrupt sources.

typedef struct asynStandardInterfaces {
    asynInterface common;

    asynInterface drvUser;

    asynInterface option;

    asynInterface octet;
    int octetProcessEosIn;
    int octetProcessEosOut;
    int octetInterruptProcess;
    int octetCanInterrupt;
    void *octetInterruptPvt;

    asynInterface uInt32Digital;
    int uInt32DigitalCanInterrupt;
    void *uInt32DigitalInterruptPvt;

    asynInterface int32;
    int int32CanInterrupt;
    void *int32InterruptPvt;

    asynInterface float64;
    int float64CanInterrupt;
    void *float64InterruptPvt;

    asynInterface int8Array;
    int int8ArrayCanInterrupt;
    void *int8ArrayInterruptPvt;

    asynInterface int16Array;
    int int16ArrayCanInterrupt;
    void *int16ArrayInterruptPvt;

    asynInterface int32Array;
    int int32ArrayCanInterrupt;
    void *int32ArrayInterruptPvt;

    asynInterface float32Array;
    int float32ArrayCanInterrupt;
    void *float32ArrayInterruptPvt;

    asynInterface float64Array;
    int float64ArrayCanInterrupt;
    void *float64ArrayInterruptPvt;

    asynInterface genericPointer;
    int genericPointerCanInterrupt;
    void *genericPointerInterruptPvt;

    asynInterface Enum;
    int enumCanInterrupt;
    void *enumInterruptPvt;

} asynStandardInterfaces;

asynStandardInterfacesBase interface

The following is the definition of the asynStandardInterfacesBase interface.

typedef struct asynStandardInterfacesBase {
    asynStatus (*initialize)(const char *portName, asynStandardInterfaces *pInterfaces, 
                             asynUser *pasynUser, void *pPvt);
} asynStandardInterfacesBase;

epicsShareExtern asynStandardInterfacesBase *pasynStandardInterfacesBase;

asynStandardInterfacesBase has a single method, initialize(), which calls registerInterface or Base->initialize for each interface which has a non-NULL value in its .pinterface field. It also calls registerInterruptSource for interfaces that are defined and that have the CanInterrupt flag set to 1. The pasynUser argument to the initialize() method is used only to provide a place for the method to return an error message (in pasynUser->errorMessage) so the invoking routine may reuse or free the asynUser structure when the method has returned.

The following is an example of the code required in a port driver that uses the asynStandardInterfacesBase interface.

#include <asynStandardInterfaces.h>
...
typedef struct drvADPvt {
...
    /* The asyn interfaces this driver implements */
    asynStandardInterfaces asynStdInterfaces;

    /* asynUser connected to ourselves for asynTrace */
    asynUser *pasynUser;
...
} drvADPvt;
...
/* Structures with function pointers for each of the asyn interfaces */
static asynCommon ifaceCommon = {
    report,
    connect,
    disconnect
};

static asynInt32 ifaceInt32 = {
    writeInt32,
    readInt32,
    getBounds
};

static asynFloat64 ifaceFloat64 = {
    writeFloat64,
    readFloat64
};

static asynOctet ifaceOctet = {
    writeOctet,
    NULL,
    readOctet,
};

static asynDrvUser ifaceDrvUser = {
    drvUserCreate,
    drvUserGetType,
    drvUserDestroy
};

static asynGenericPointer ifaceGenericPointer = {
    writeADImage,
    readADImage
};
...

int simDetectorConfig(const char *portName, int maxSizeX, int maxSizeY, int dataType)

{
    drvADPvt *pPvt;
    int status = asynSuccess;
    char *functionName = "simDetectorConfig";
    asynStandardInterfaces *pInterfaces;

    pPvt = callocMustSucceed(1, sizeof(*pPvt), functionName);
    pPvt->portName = epicsStrDup(portName);

    status = pasynManager->registerPort(portName,
                                        ASYN_MULTIDEVICE | ASYN_CANBLOCK,
                                        1,  /*  autoconnect */
                                        0,  /* medium priority */
                                        0); /* default stack size */
    if (status != asynSuccess) {
        printf("%s ERROR: Can't register port\n", functionName);
        return(asynError);
    }

    /* Create asynUser for debugging */
    pPvt->pasynUser = pasynManager->createAsynUser(0, 0);

    pInterfaces = &pPvt->asynStdInterfaces;
    
    /* Initialize interface pointers */
    pInterfaces->common.pinterface         = (void *)&ifaceCommon;
    pInterfaces->drvUser.pinterface        = (void *)&ifaceDrvUser;
    pInterfaces->octet.pinterface          = (void *)&ifaceOctet;
    pInterfaces->int32.pinterface          = (void *)&ifaceInt32;
    pInterfaces->float64.pinterface        = (void *)&ifaceFloat64;
    pInterfaces->genericPointer.pinterface = (void *)&ifaceGenericPointer;

    /* Define which interfaces can generate interrupts */
    pInterfaces->octetCanInterrupt          = 1;
    pInterfaces->int32CanInterrupt          = 1;
    pInterfaces->float64CanInterrupt        = 1;
    pInterfaces->genericPointerCanInterrupt = 1;

    status = pasynStandardInterfacesBase->initialize(portName, pInterfaces,
                                                     pPvt->pasynUser, pPvt);
    if (status != asynSuccess) {
        printf("%s ERROR: Can't register interfaces: %s.\n",
               functionName, pPvt->pasynUser->errorMessage);
        return(asynError);
    }
...
}

Standard Interpose Interfaces

asynInterposeEos

This can be used to simulate EOS processing for asynOctet if the port driver doesn't provide EOS support. If an EOS is specified it looks for the eos on each read. It is started by the shell command:

    asynInterposeEosConfig port addr processEosIn processEosOut

where

This command should appear immediately after the command that initializes a port Some drivers provide configuration options to call this automatically.

asynInterposeFlush

This can be used to simulate flush processing for asynOctet if the port driver doesn't provide support for flush. It just reads and discards characters until no more characters arive before timeout seconds have occured. It is started by the shell command:

    asynInterposeFlushConfig port addr timeout

where

this command should appear immediately after the command that initializes a port


Generic Device Support for EPICS records

Generic device support is provided for standard EPICS records. This support should be usable for a large class of low level register based drivers. For complicated devices other support is required. This release provides the following:

The support uses the following conventions for DTYP and INP. OUT fields are the same as INP.

    field(DTYP,"asynXXX")
    field(INP,"@asyn(portName,addr,timeout)drvParams")
     or
    field(INP,"@asynMask(portName,addr,mask,timeout)drvParams")
where

For example:

    field(DTYP,"asynInt32")
    field(INP,"@asyn(portA,0,.1)thisIsForDriver")

asynManager interrupts and EPICS device support

All of the device support files can call registerInterruptUser for input records. The callback is used in one of two ways:

Initial values of output records

The device support for output records on register based interfaces (bo, mbbo, ao, longout) does an initial read() of the value from the driver in init_record. If this read() returns asynSuccess then the record value is set to the value returned from read(). If read() returns anything other than asynSuccess then the record value is not modified. This mechanism supports "bumpless reboots" where the initial value of output records will match the current value of the hardware when the IOC starts. Drivers should only return asynSuccess from the read() function if the value is known to be valid. Note that this value read from the device will replace the value in the database when iocInit begins. However, the value read from the device may in turn be replaced by any value from save/restore, because the auto restore happens later in iocInit.

Enum values for bi, bo, mbbi, and mbbo records

Beginning in asyn R4-19 support was added for asyn port drivers to control the values of the enum strings, enum values and enum severities in bi, bo, mbbi, and mbbo records. This is implemented in the asynInt32 and asynUInt32Digital device support as follows:

Callback updates for output records

Beginning in asyn R4-26 support was added for updating output records from driver interrupt callbacks. This feature allows output records to reflect changes in the underlying hardware that are caused by manual front-panel operation, changes caused by another output record, etc.

By default output records do not update when a driver does interrupt callbacks. However, if the following info tag is added for a record in the database file then callbacks will be enabled and the output record will be updated whenever the driver does a callback for that value.
info(asyn:READBACK, "1")
If the value of the info tag is 0 or if the info tag is not present then updates of output records on interrupt callbacks are disabled.

Buffering of driver callbacks

It is possible for the time between driver callbacks to be less than the time for record processing. asyn device support provides a ring-buffer (FIFO) mechanism to buffer values so that the record will process all callback values from a short burst of callbacks. For all records except stringin, stringout, and waveform records the default buffer size is 10 values. For stringin, stringout, and waveform records the default buffer size is 0, i.e. there is no buffering. For all record types the size of the buffer can be controlled by the following info tag for a record in the database file:
info(asyn:FIFO, "20")
In this example the buffer size was set to 20. Ring buffer support was added in asyn R4-10 for all records except stringin, stringout, and waveform. Waveform record support for numeric arrays was added in asyn R4-25. asynOctet support for stringin, stringout, and waveform records was added in asyn R4-26.

Time stamps

Beginning in asyn R4-20 support was added for asyn port drivers to set the TIME field of input records. This is done by setting the TSE field of the record to "-2" and setting the desired value into the timestamp field of the pasynUser structure referred to in the device read method or interrupt callback.

Beginning in asyn R4-22 the timestamp support functions were added to asynManager to update, get and set the most recent timestamp for the port in asynManager. Support was also added for user-supplied timestamp source functions. Timestamp support was also added to asynPortDriver for the base-class read functions and callback functions.

asynInt32 device support

The following support is available:

device(ai,INST_IO,asynAiInt32,"asynInt32")
device(ai,INST_IO,asynAiInt32Average,"asynInt32Average")
device(ao,INST_IO,asynAoInt32,"asynInt32")
device(bi,INST_IO,asynBiInt32,"asynInt32")
device(bo,INST_IO,asynBoInt32,"asynInt32")
device(mbbi,INST_IO,asynMbbiInt32,"asynInt32")
device(mbbo,INST_IO,asynMbboInt32,"asynInt32")
device(longin,INST_IO,asynLiInt32,"asynInt32")
device(longout,INST_IO,asynLoInt32,"asynInt32")

devAsynInt32.c provides EPICS device support for drivers that implement interface asynInt32.

For ai and ao records either of the following specifications for the INP and OUT fields can be used:

    
    field(INP,"@asyn(portName,addr,timeout) drvParams")
     or
    field(INP,"@asynMask(portName,addr,nbits,timeout) drvParams")

The asynMask format allows device support to work with drivers that cannot return meaningful values from getBounds() because they do not know the range of the device. This is true, for example, of Modbus ADCs. The nbits parameter is defined as follows:

nbits > 0  Device is unipolar with a range from 0 to 2^nbits-1.  Values will be masked to the specified number of bits.

nbits < 0 Device is bipolar with a range from -2^(abs(nbits)-1) to 2^((abs(nbits)-1)-1 Values read with the asynInt32 interface will be sign extended using the sign bit (e.g. bit abs(nbits)-1 starting at bit 0).

Analog Input Example Records

   record(ai,"aiInt32") {
        field(SCAN,"I/O Intr")
        field(DTYP,"asynInt32")
        field(INP,"@asyn($(port),$(addr))")
        field(EGUF,"10.0")
        field(EGUL,"-10.0")
        field(PREC,"3")
   }
   # This record is for a 12-bit bipolar ADC for a driver that does not
   # support getBounds()
   record(ai,"aiInt32") {
        field(SCAN,"I/O Intr")
        field(DTYP,"asynInt32")
        field(INP,"@asynMask($(port),$(addr),-12)")
        field(EGUF,"10.0")
        field(EGUL,"-10.0")
        field(PREC,"3")
   }
   record(ai,"aiInt32Average") {
        field(SCAN,"10 second")
        field(DTYP,"asynInt32Average")
        field(INP,"@asyn($(port),$(addr))")
        field(EGUF,"10.0")
        field(EGUL,"-10.0")
        field(PREC,"3")
   }

Analog Output Example Record

   record(ao,"aoInt32") {
        field(DTYP,"asynInt32")
        field(OUT,"@asyn($(port),$(addr))")
        field(EGUF,"10.0")
        field(EGUL,"-10.0")
        field(PREC,"3")
   }

Long Input Example Records

   record(longin,"liInt32") {
        field(SCAN,"I/O Intr")
        field(DTYP,"asynInt32")
        field(INP,"@asyn($(port),$(addr))")
   }

Long Output Example Record

   record(longout,"loInt32") {
        field(DTYP,"asynInt32")
        field(OUT,"@asyn($(port),$(addr))")
   }

Multibit Binary Input Example Records

   record(mbbi,"mbbiInt32") {
        field(SCAN,"I/O Intr")
        field(DTYP,"asynInt32")
        field(INP,"@asyn($(port),$(addr))")
        field(NOBT,"2")
        field(SHFT,"2")
        field(ZRST,"zeroVal")
        field(ONST,"oneVal")
        field(TWST,"twoVal")
        field(THST,"threeVal")
   }

Multibit Binary Output Example Record

   record(mbbo,"mbboInt32") {
        field(DTYP,"asynInt32")
        field(OUT,"@asyn($(port),$(addr))")
        field(NOBT,"2")
        field(SHFT,"16")
        field(ZRST,"zeroVal")
        field(ONST,"oneVal")
        field(TWST,"twoVal")
        field(THST,"threeVal")
   }

asynIntXXXArray device support (XXX=8, 16 or 32)

The following support is available:

device(waveform,INST_IO,asynIntXXXArrayWfIn,"asynIntXXXArrayIn")
device(waveform,INST_IO,asynIntXXXArrayWfOut,"asynIntXXXArrayOut")

devAsynIntXXXArray.c provides EPICS device support for drivers that implement interface asynIntXXXArray. It has support for both reading and writing a waveform. SCAN "I/O Intr" is supported similar to the aiRecord in devAsynInt32 device support.

asynXXXTimeSeries device support (XXX=Int32 or Float64)

The following support is available:

device(waveform,INST_IO,asynInt32TimeSeries,"asynInt32TimeSeries")
device(waveform,INST_IO,asynFloat64TimeSeries,"asynFloat64TimSeries")

devAsynXXXTimeSeries.c provides EPICS device support to collect a time series of values into a waveform record. It works with drivers that implement callbacks on the asynInt32 or asynFloat64 interfaces. This permits more rapid and efficient acquisition of values from a driver than can be obtained using record support and database operations. The waveform record RARM field is used to control acquisition as follows:

devAsynUInt32Digital

The following support is available:

device(bi,INST_IO,asynBiUInt32Digital,"asynUInt32Digital")
device(bo,INST_IO,asynBoUInt32Digital,"asynUInt32Digital")
device(longin,INST_IO,asynLiUInt32Digital,"asynUInt32Digital")
device(longout,INST_IO,asynLoUInt32Digital,"asynUInt32Digital")
device(mbbi,INST_IO,asynMbbiUInt32Digital,"asynUInt32Digital")
device(mbbo,INST_IO,asynMbboUInt32Digital,"asynUInt32Digital")
device(mbbiDirect,INST_IO,asynMbbiDirectUInt32Digital,"asynUInt32Digital")
device(mbboDirect,INST_IO,asynMbboDirectUInt32Digital,"asynUInt32Digital")

devAsynUInt32Digital.c provides EPICS device support for drivers that implement interface asynUInt32Digital. The INP or OUT field must define asynMask. The mask specified in the argument to asynMask is used in the calls to asynUInt32Digital methods. In addition it is used to set the mask fields in bi and bo records and the mask and shft fields in mbbi, mbbo, mbbiDirect, and mbboDirect records.

Binary Input Example Record

record(bi,"biUInt32Bit0") {
    field(SCAN,"I/O Intr")
    field(DTYP,"asynUInt32Digital")
    field(INP,"@asynMask( $(port) , 0, 0x1 , 1.0) ")
    field(ZNAM,"zero")
    field(ONAM,"one")
}

Binary Output Example Record

record(bo,"boUInt32Bit2") {
    field(DTYP,"asynUInt32Digital")
    field(OUT,"@asynMask( $(port) , 0, 0x4 , 1.0) ")
    field(ZNAM,"zero")
    field(ONAM,"one")
}

Long Input Example Record

record(longin,"liUInt32") {
    field(SCAN,"I/O Intr")
    field(DTYP,"asynUInt32Digital")
    field(INP,"@asynMask( $(port) , 0, 0xffffffff , 1.0) ")
}

Long Output Example Record

record(longout,"loUInt32") {
    field(DTYP,"asynUInt32Digital")
    field(INP,"@asynMask( $(port) , 0, 0xffffffff , 1.0) ")
}

Multibit Input Example Record

record(mbbi,"mbbiUInt32") {
    field(SCAN,"I/O Intr")
    field(DTYP,"asynUInt32Digital")
    field(INP,"@asynMask( digital , 0, 0x3 , 1.0) ")
    field(ZRST,"zero")
    field(ONST,"one")
    field(TWST,"two")
    field(THST,"three")
    field(ZRVL,"0x0")
    field(ONVL,"0x1")
    field(TWVL,"0x2")
    field(THVL,"0x3")
}

Multibit Output Example Record

record(mbbo,"mbboUInt32") {
    field(DTYP,"asynUInt32Digital")
    field(OUT,"@asynMask( digital , 0, 0x7 , 1.0) ")
    field(ZRST,"zero")
    field(ONST,"one")
    field(TWST,"two")
    field(THST,"three")
    field(FRST,"four")
    field(FVST,"five")
    field(SXST,"six")
    field(SVST,"seven")
    field(ZRVL,"0x0")
    field(ONVL,"0x1")
    field(TWVL,"0x2")
    field(THVL,"0x3")
    field(FRVL,"0x4")
    field(FVVL,"0x5")
    field(SXVL,"0x6")
    field(SVVL,"0x7")
}

devAsynFloat64 device support

The following support is available:

device(ai,INST_IO,asynAiFloat64,"asynFloat64")
device(ai,INST_IO,asynAiFloat64Average,"asynFloat64Average")
device(ao,INST_IO,asynAoFloat64,"asynFloat64")

devAsynFloat64.c provides EPICS device support for drivers that implement interface asynFloat64.

asynFloatXXXArray device support (where XXX=32 or 64)

The following support is available:

device(waveform,INST_IO,asynFloatXXXArrayWfIn,"asynFloatXXXArrayIn")
device(waveform,INST_IO,asynFloatXXXArrayWfOut,"asynFloatXXXArrayOut")

devAsynFloatXXXArray.c provides EPICS device support for drivers that implement interface asynFloatXXXArray. It has support for both reading and writing a waveform. SCAN "I/O Intr" is supported similar to the aiRecord in devAsynInt32 device support.

octet device support

The following support is available:

device(stringin,INST_IO,asynSiOctetCmdResponse,"asynOctetCmdResponse")
device(stringin,INST_IO,asynSiOctetWriteRead,"asynOctetWriteRead")
device(stringin,INST_IO,asynSiOctetRead,"asynOctetRead")
device(stringout,INST_IO,asynSoOctetWrite,"asynOctetWrite")
device(waveform,INST_IO,asynWfOctetCmdResponse,"asynOctetCmdResponse")
device(waveform,INST_IO,asynWfOctetWriteRead,"asynOctetWriteRead")
device(waveform,INST_IO,asynWfOctetRead,"asynOctetRead")
device(waveform,INST_IO,asynWfOctetWrite,"asynOctetWrite")

Support for drivers that implement interface asynOctet. The support is for stringin/stringout and waveform records. The waveform support is similar to the string support. The waveform records must define FTVL to be CHAR or UCHAR, i.e. it must be an array of octets. The waveform provides the following features not provided by the string support:

Four types of support are provided:

Record alarms

The generic EPICS device support sets the record alarm status and severity when errors occur. For records that do not use callbacks (not SCAN=I/O Intr or asynXXXAverage or asynXXXTimeSeries) the status information is passed from the driver to device support in the asynStatus return of the interface function call, e.g. pasynInt32->read(). The driver maps the asynStatus values to the record STAT and SEVR values using the function pasynEpicsUtils->asynUserToEpicsAlarm(). The SEVR field is currently always set to INVALID_ALARM for any error. The STAT field is set using following mapping:

  asynSuccess = epicsAlarmNone
  asynTimeout = epicsAlarmTimeout
  asynOverflow = epicsAlarmHWLimit
  asynError = epicsAlarmRead or epicsAlarmWrite
  asynDisconnected = epicsAlarmComm
  asynDisabled = epicsAlarmDisable
  

For records that use callbacks, the status information is passed from the driver to device support using the pasynUser->auxStatus field in the pasynUser that is passed in the callback. This feature was added in asyn R4-19. Prior to that release it was not possible for drivers to control the alarm state of records that used callbacks. Drivers should set pasynUser->auxStatus to asynSuccess for normal operation and to another value to indicate a problem. The same mapping described above is used to control the values of STAT and SEVR.


asynRecord: Generic EPICS Record Support

A special record type asynRecord is provided. Details are described in asynRecord. This section provides a brief description of how to use it.

Each IOC can load one or more instances of asynRecord. An example is:

cd $(ASYN)
dbLoadRecords("db/asynRecord.db","P=asyn,R=Test,PORT=L0,ADDR=15,IMAX=0,OMAX=0")

The example creates a record with name "asynTest" (formed from the concatenation of the P and R macros) that will connect to port "L0" and addr 15. After the ioc is started, it is possible to change PORT and/or ADDR. Thus, a single record can be used to access all asyn devices connected to the IOC. Multiple records are only needed if one or more devices need a dedicated record.

An medm display is available for accessing an asynRecord. It is started as follows:

cd <asyn>/medm
medm -x -macro "P=asyn,R=Test" asynRecord.adl

The following medm display appears.

asynRecord.png


Example

The following reads from a device via octet messages:

#include <asynDriver.h>
...
#define BUFFER_SIZE 80
typedef struct myData {
    epicsEventId done;
    asynOctet    *pasynOctet;
    void         *drvPvt;
    char         buffer[BUFFER_SIZE];
}myData;

static void queueCallback(asynUser *pasynUser) {
    myData     *pmydata = (myData *)pasynUser->userPvt;
    asynOctet  *pasynOctet = pmydata->pasynOctet;
    void       *drvPvt = pmydata->drvPvt;
    asynStatus status;
    int        writeBytes,readBytes;
    int        eomReason;

    asynPrint(pasynUser,ASYN_TRACE_FLOW,"queueCallback entered\n");
    status = pasynOctet->write(drvPvt,pasynUser,pmydata->buffer,
              strlen(pmydata->buffer),&writeBytes);
    if(status!=asynSuccess) {
        asynPrint(pasynUser,ASYN_TRACE_ERROR,
            "queueCallback write failed %s\n",pasynUser->errorMessage);
    } else {
        asynPrintIO(pasynUser,ASYN_TRACEIO_DEVICE,
            pmydata->buffer,strlen(pmydata->buffer),
            "queueCallback write sent %d bytes\n",writeBytes);
    }
    status = pasynOctet->read(drvPvt,pasynUser,pmydata->buffer,
         BUFFER_SIZE,&readBytes,&eomReason);
    if(status!=asynSuccess) {
        asynPrint(pasynUser,ASYN_TRACE_ERROR,
            "queueCallback read failed %s\n",pasynUser->errorMessage);
    } else {
        asynPrintIO(pasynUser,ASYN_TRACEIO_DEVICE,
            pmydata->buffer,BUFFER_SIZE,
            "queueCallback read returned: retlen %d eomReason 0x%x data %s\n",
            readBytes,eomReason,pmydata->buffer);
    }
    epicsEventSignal(pmydata->done);
}

static void asynExample(const char *port,int addr,const char *message)
{
    myData        *pmyData;
    asynUser      *pasynUser;
    asynStatus    status;
    asynInterface *pasynInterface;

    pmyData = (myData *)pasynManager->memMalloc(sizeof(myData));
    memset(pmyData,0,sizeof(myData));
    strcpy(pmyData->buffer,message);
    pasynUser = pasynManager->createAsynUser(queueCallback,0);
    pasynUser->userPvt = pmyData;
    status = pasynManager->connectDevice(pasynUser,port,addr);
    if(status!=asynSuccess) {
        printf("can't connect to serialPort1 %s\n",pasynUser->errorMessage);
        exit(1);
    }
    pasynInterface = pasynManager->findInterface(
        pasynUser,asynOctetType,1);
    if(!pasynInterface) {
        printf("%s driver not supported\n",asynOctetType);
        exit(-1);
    }
    pmyData->pasynOctet = (asynOctet *)pasynInterface->pinterface;
    pmyData->drvPvt = pasynInterface->drvPvt;
    pmyData->done = epicsEventCreate(epicsEventEmpty);
    status = pasynManager->queueRequest(pasynUser,asynQueuePriorityLow, 0.0);
    if(status) {
        asynPrint(pasynUser,ASYN_TRACE_ERROR,
            "queueRequest failed %s\n",pasynUser->errorMessage);
    }
    epicsEventWait(pmyData->done);
    status = pasynManager->freeAsynUser(pasynUser);
    if(status) {
        asynPrint(pasynUser,ASYN_TRACE_ERROR,
            "freeAsynUser failed %s\n",pasynUser->errorMessage);
    }
    epicsEventDestroy(pmyData->done);
    pasynManager->memFree(pasynUser->userPvt,sizeof(myData));
}

The flow of control is as follows:

  1. A port driver calls registerPort. This step is not shown in the above example.
  2. asynExample allocates myData and an asynUser.
  3. asynExample connects to a device and to the asynOctet interface for the port driver.
  4. When it is ready to communicate with the driver it calls queueRequest.
  5. queueCallback is called. It calls the port driver's write and read methods.

Test Application

The asynDriver distribution includes code to test asynDriver. It is also an example of how to interface to asynManager. The example resides in <top>/testApp and contains the following components:

Db/
   test.db
   testBlock.db
adl/
   test.adl
src/
   devTestBlock.dbd
   echoDriver.c
   addrChangeDriver.c
   devTestBlock.c
   interposeInterface.c

echoDriver is a port driver that echos messages it receives. It implements asynCommon and asynOctet. When asynOctet:write is called it saves the message. When asynOctet:read is called, the saved message is returned and the message is flushed. echoDriverInit has an argument that determines if it acts like a multiDevice or a single device port driver.

An instance of echoDriver is started via the iocsh command:

echoDriverInit(portName,delay,noAutoConnect,multiDevice)

where

addrChangeDriver is a multidevice driver that is an asynUser of another port driver. In the example application it connects to echoDriver. An example where this technique might be used is a port driver for mult-drop serial that connects to a standard serial port.

An instance of addrChangeDriver is started via the iocsh commandL:

addrChangeDriverInit(portName,lowerPort,addr)

where

devTestBlock is device support that tests blockProcessCallback. It has device support for stringin records. The INP field has the syntax:

    field(INP,"@asyn(port,addr,timeout) pvname)

where:

When the stringin record is processed the following occurs.

test.db is a template containing three records: a calc record, which forward links to a stringout record which forward links to a stringin record. The stringOut record attaches to the device support supplied by asynOctetWriteRead.c. When the calcRecord is processed the following happens:

testBlock.db is a template similar to test.db except that it attached to device support testBlock instead of asynOctetWriteRead.

Executing "medm -x test.adl" produces the display:

asynTest.png

It assumes that an ioc has been started via:

cd <top>/iocBoot/ioctest
../../bin/solaris-sparc/test st.cmd

This starts two versions of echoDriver as port "A" and "B". port A acts as single device port. port B acts as a multiDevice port that has two devices. For each of the three possible devices, the st.cmd file starts up two sets of records from test.db The st.cmd file also loads a set of records from asynTest.db for port A and for port B and for each of the two devices attached to port B. It also loads a set of records from asynRecord.db. It starts one version of addrChangeDriver which connects to port A.

It loads six versions of test.db and four versions of testBlock.db The test.adl file attaches to these database records.


asynGpib

GPIB has additional features that are not supported by asynCommon and asynOctet. asynGpib defines two interfaces.

asynGpibDriver.h

asynGpibDriver.h contains the following definitions:

/* GPIB Addressed Commands*/
#define IBGTL "\x01"    /* Go to local */
#define IBSDC "\x04"    /* Selective Device Clear */
#define IBGET "\x08"    /* Group Execute Trigger */
#define IBTCT "\x09"    /* Take Control */

/* GPIB Universal Commands*/
#define IBDCL 0x14      /* Device Clear */
#define IBLLO 0x11      /* Local Lockout */
#define IBSPE 0x18      /* Serial Poll Enable */
#define IBSPD 0x19      /* Serial Poll Disable */
#define IBUNT 0x5f      /* Untalk */
#define IBUNL 0x3f      /* Unlisten */

/* Talk, Listen, Secondary base addresses */
#define TADBASE    0x40   /* offset to GPIB listen address 0 */
#define LADBASE    0x20   /* offset to GPIB talk address 0 */
#define SADBASE    0x60   /* offset to GPIB secondary address 0 */

#define NUM_GPIB_ADDRESSES    32
#include "asynDriver.h"
#include "asynInt32.h"
#define asynGpibType "asynGpib"
/* GPIB drivers */
typedef struct asynGpib asynGpib;
typedef struct asynGpibPort asynGpibPort;
/*asynGpib defines methods called by gpib aware users*/
struct asynGpib{
    /*addressedCmd,...,ren are just passed to device handler*/
    asynStatus (*addressedCmd) (void *drvPvt,asynUser *pasynUser,
        const char *data, int length);
    asynStatus (*universalCmd) (void *drvPvt,asynUser *pasynUser,int cmd);
    asynStatus (*ifc) (void *drvPvt,asynUser *pasynUser);
    asynStatus (*ren) (void *drvPvt,asynUser *pasynUser, int onOff);
    /* The following are implemented by asynGpib */
    asynStatus (*pollAddr)(void *drvPvt,asynUser *pasynUser, int onOff);
    /* The following are called by low level gpib drivers */
    /*srqHappened is passed the pointer returned by registerPort*/
    void *(*registerPort)(
        const char *portName,
        int attributes,int autoConnect,
        asynGpibPort *pasynGpibPort, void *asynGpibPortPvt,
        unsigned int priority, unsigned int stackSize);
    void (*srqHappened)(void *asynGpibPvt);
};
epicsShareExtern asynGpib *pasynGpib;

struct asynGpibPort {
    /*asynCommon methods */
    void (*report)(void *drvPvt,FILE *fd,int details);
    asynStatus (*connect)(void *drvPvt,asynUser *pasynUser);
    asynStatus (*disconnect)(void *drvPvt,asynUser *pasynUser);
    /*asynOctet methods passed through from asynGpib*/
    asynStatus (*read)(void *drvPvt,asynUser *pasynUser,
                      char *data,int maxchars,int *nbytesTransfered,
                      int *eomReason);
    asynStatus (*write)(void *drvPvt,asynUser *pasynUser,
                      const char *data,int numchars,int *nbytesTransfered);
    asynStatus (*flush)(void *drvPvt,asynUser *pasynUser);
    asynStatus (*setEos)(void *drvPvt,asynUser *pasynUser,
                const char *eos,int eoslen);
    asynStatus (*getEos)(void *drvPvt,asynUser *pasynUser,
                char *eos, int eossize, int *eoslen);
    /*asynGpib methods passed thrtough from asynGpib*/
    asynStatus (*addressedCmd) (void *drvPvt,asynUser *pasynUser,
                const char *data, int length);
    asynStatus (*universalCmd) (void *drvPvt, asynUser *pasynUser, int cmd);
    asynStatus (*ifc) (void *drvPvt,asynUser *pasynUser);
    asynStatus (*ren) (void *drvPvt,asynUser *pasynUser, int onOff);
    /*asynGpibPort specific methods */
    asynStatus (*srqStatus) (void *drvPvt,int *isSet);
    asynStatus (*srqEnable) (void *drvPvt, int onOff);
    asynStatus (*serialPollBegin) (void *drvPvt);
    asynStatus (*serialPoll) (void *drvPvt, int addr, double timeout,int *status);
    asynStatus (*serialPollEnd) (void *drvPvt);
};

asynGpib

asynGpib describes the interface for device support code. It provides gpib specific functions like SRQ handling. It makes calls to asynGpibPort. asynGpib.c implements asynCommon and asynOctet. It supports asynInt32 by using the methods from asynInt32Base. asynInt32 is the way asynGpib reports SRQs to asynUsers.

An asynUser that wishes to receive SRQs calls pasynInt32->registerInterruptUser and must set asynUser.reason = ASYN_REASON_SIGNAL. Although most gpib controllers are multidevice drivers, the VXI11 standard allows for a controller (VXI-11.2) that attached to a single device, i.e. it is a single address port driver. For such controllers, the use must specify addr = 0 in order to use SRQs. Also see the vxi support below for more details.

asynGpib
addressedCmd The request is passed to the low level driver.
universalCmd The request is passed to the low level driver.
ifc The request is passed to the low level driver.
ren The request is passed to the low level driver.
pollAddr Set SRQ polling on or off. onOff = (0,1) means (disable, enable) SRQ polling of specified address.
registerPort Register a port. When asynGpib receives this request, it calls asynManager.registerPort.
srqHappened Called by low level driver when it detects that a GPIB device issues an SRQ.

asynGpibPort

asynGpibPort is the interface that is implemented by gpib drivers, e.g. the VXI-11. It provides:

asynGpibPort
asynCommon methods All the methods of asynCommon
asynOctet methods All the methods of asynOctet
addressedCmd Issue a GPIB addressed command.
universalCmd Issue a GPIB universal command.
ifc Issue a GPIB Interface Clear command.
ren Issue a GPIB Remote Enable command
srqStatus If return is asynSuccess then isSet is (0,1) if SRQ (is not, is) active. Normally only called by asynGpib.
srqEnable Enable or disable SRQs. Normally only called by asynGpib.
serialPollBegin Start of serial poll. Normally only called by asynGpib.
serialPoll Poll the specified address and set status to the response. Normally only called by asynGpib.
serialPollEnd End of serial poll. Normally only called by asynGpib.

Port Drivers

Local Serial Port

The drvAsynSerialPort driver supports devices connected to serial ports on the IOC.

Serial ports are configured with the drvAsynSerialPortConfigure and asynSetOption commands:

   drvAsynSerialPortConfigure("portName","ttyName",priority,noAutoConnect,
        noProcessEosIn)
   asynSetOption("portName",addr,"key","value")

where the arguments are:

The setEos and getEos methods have no effect and return asynError. The read method blocks until at least one character has been received or until a timeout occurs. The read method transfers as many characters as possible, limited by the specified count. asynInterposeEos can be used to support EOS.

The following table summarizes the drvAsynSerialPort driver asynSetOption keys and values. When a serial port connects the current values are fetched.

Key Value
baud 50 75 110 134 150 200 300 600 1200 2400 9600 ...
bits 8 7 6 5
parity none even odd
stop 1 2
clocal Y N
crtscts N Y
ixon N Y
ixoff N Y
ixany N Y

On some systems (e.g. Windows, Darwin) the driver accepts any numeric value for the baud rate, which must, of course be supported by the system hardware. On Linux the choices are limited to the values like B300, B9600, etc. which are defined in /usr/include/bits/termios.h.

The clocal and crtscts parameter names are taken from the POSIX termios serial interface definition. The clocal parameter controls whether the modem control lines (Data Terminal Ready, Carrier Detect/Received Line Signal Detect) are used (clocal=N) or ignored (clocal=Y). The crtscts parameter controls whether the hardware handshaking lines (Request To Send, Clear To Send) are used (crtscts=Y) or ignored (crtscts=N).

The vxWorks sioLib serial support does not provide support for modem control lines. It also uses clocal for what is actually crtscts. For vxWorks the standard serial support accepts both clocal and crtscts for getOption and setOption. clocal=Y implies crtscts=N and clocal=N implies crtscts=Y.

ixon controls XON/OFF flow control on output. If the IOC receives an XOFF character, it suspends output until an XON character is received.

ixoff controls XON/OFF flow control on input. The IOC sends XOFF and XON characters as necessary to prevent input from coming in faster than programs are reading it. The external device sending the input data must respond to an XOFF character by suspending transmission, and to an XON character by resuming transmission.

The ixany flag allows any input character to restart output when output has been suspended with the XOFF character. Otherwise, only the XON character restarts output. This flag is not available on all systems, including WIN32.

vxWorks IOC serial ports may need to be set up using hardware-specific commands. Once this is done, the standard drvAsynSerialPortConfigure and asynSetOption commands can be issued. For example, the following example shows the configuration procedure for a port on a GreenSprings octal UART Industry-Pack module on a GreenSprings VIP616-01 carrier.

ipacAddVIPC616_01("0x6000,B0000000")
tyGSOctalDrv(1)
tyGSOctalModuleInit("Mod0","232", 0x80, 0, 0)
tyGSOctalDevCreate("/tyGS/0/0","Mod0",0,0,1000,1000)
drvAsynSerialPortConfigure("/tyGS/0/0","/tyGS/0/0",0,0,0)
asynSetOption("/tyGS/0/0",0,"baud","9600")

For the IP520:

IP520Drv(1)
IP520ModuleInit("UART_0", "232", 0xC2, 0, 0)
IP520DevCreate("A1", "UART_0", 0, 0, 1000, 1000)
drvAsynSerialPortConfigure("A1","A1",0,0,0)
asynSetOption("A1",0,"baud",9600)
asynOctetSetInputEos( "A1",0,"\r")
asynOctetSetOutputEos("A1",0,"\r")

TCP/IP or UDP/IP Port

The drvAsynIPPort driver supports devices which communicate over a TCP/IP or UDP/IP connection. A typical example is a device connected through an Ethernet/Serial converter box.

TCP/IP or UDP/IP connections are configured with the drvAsynIPPortConfigure command:

   drvAsynIPPortConfigure("portName","hostInfo",priority,noAutoConnect,
        noProcessEos)

where the arguments are:

Only asynOctet methods write, read, and flush are implemented. Calling the other methods will result in an error unless asynInterposeEos is used for the other asunOctet methods. read blocks until at least one character has been received or until a timeout occurs. read transfers as many characters as possible, limited by the specified count.

There are no asynSetOption key/value pairs associated with drvAsynIPPort connections.

asynInterposeEos and asynInterposeFlush can be used to provide additional functionality.

TCP/IP Server

The drvAsynIPServerPort driver supports asyn socket servers by listening for TCP/IP or UDP connections from remote clients. The listener thread then creates a new drvAsynIPPort port by calling drvAsynIPPortConfigure (or re-uses a disconnected port it previously created), and calls back any registered asyn clients with the name of the new port. These asyn clients will typically be socket servers.

IP server listeners are configured with the drvAsynIPServerPortConfigure command:

 drvAsynIPServerPortConfigure("portName", "serverInfo", maxClients, priority, 
      noAutoConnect, noProcessEos);

where the arguments are:

This driver implements the asynOctet interface. The only methods it supports are registerInterruptUser and cancelInterruptUser. Calling the other asynOctet methods will result in an error. The following happens when a new connection is received on the port specified in drvAsynIPServerPortConfigure:

VXI-11

VXI-11 is a TCP/IP protocol for communicating with IEEE 488.2 devices. It is an RPC based protocol. In addition to the VXI-11 standard, three additional standards are defined.

NOTES

Consult the following documents (available on-line) for details.

VMEbus Extensions for Instrumentation
    VXI-11   TCP/IP Instrument Protocol Specification
    VXI-11.1 TCP/IP-VXIbus Interface Specification
    VXI-11.2 TCP/IP-IEEE 488.1 Interface Specification
    VXI-11.3 TCP/IP-IEEE 488.2 Instrument Interface Specification

The following commands may be specified in the st.cmd file

    E2050Reboot("inet_addr")
    E5810Reboot("inet_addr","password")
    vxi11Configure("portName","inet_addr",flags,"timeout",
        "vxiName",priority,noAutoConnect)

where

The vxi11 driver implements two timeouts: ioTimeout and rpcTimeout (Remote Procedure Call timeout). The ioTimeout is taken from asynUser:timeout. The rpcTimeout is handled internally for each port. It has a default of 4 seconds but can be changed by calling setOptions. For example:

asynSetOption L0 -1 rpctimeout .1

Will change the rpcTimeout for port L0 to .1 seconds.

Linux-Gpib

The linux-gpib port driver was written to support The Linux GPIB Package library.

In order to build this support the Linux GPIB Package must be installed. Also in configure/RELEASE the statement:

    LINUX_GPIB=NO

must be changed to

    LINUX_GPIB=YES

Configuration command is:

    GpibBoardDriverConfig(portName,autoConnect,BoardIndex,timeout,priority)

where

An example is:

GpibBoardDriverConfig("L0",1,0,3,0)

NOTES:

Green Springs IP488

This is support for the Green Springs Industry Pack GPIB carrier. The configuration command is:

    gsIP488Configure(portName,carrier,module,intVec,priority,noAutoConnect)

where

An example is:

#The following is for the Greensprings IP488 on an MV162 
ipacAddMVME162("A:l=3,3 m=0xe0000000,64")
gsIP488Configure("L0",0,0,0x61,0,0)

WARNING:

This module includes code that implement a 6 microsecond delay because the gpib interface chip requires it. The first time gsIP488Configure is executed code is run to determine a variable used by the delay routine. It assumes that there is no higher priority thread running that consumes lots of cpu cycles.

National Instruments GPIB-1014D

This is support for a National Instruments VME GPIB interface. The configuration command is:

    ni1014Config(portNameA,portNameB,base,vector,level,priority,noAutoConnect)

where

An example is:

ni1014Config("L0","L1",0x5000,0x64,5,0,0)

NOTES:

WARNING:

This module includes code that implement a 6 microsecond delay because the gpib interface chip requires it. The first time ni1014Config is executed code is run to determine a variable used by the delay routine. It assumes that there is no higher priority thread running that consumes lots of cpu cycles.

USB TMC (Test and Measurement Class) driver

Configure each instance of the driver in the application startup script:

usbtmcConfigure("asynPort", vendorId, productId, "serialNumber", priority, flags)

The asynPort and serialNumber arguments are strings and the other arguments are integers. A missing or 0 vendorId or productId matches any value and a missing or empty serialNumber string matches any value. Thus the command:

usbtmcConfigure("usbtmc1")

will associate ASYN port usbtmc1 with the first USB TMC device discovered. A missing or 0 priority will set the worker thread priority to its default value of 50 (epicsThreadPriorityMedium).

A missing flags argument is taken to be 0. As of now only one bit is used: Bit 0 (0x1) Disable/enable (1/0) automatic port connection.

Non-octet records

In addition to the asynOctet stream this support module provides some values for records with DTYP=asynInt32. Since the port is a single-address device the subaddress field of the INP or OUT '@asyn()' descriptor can not be used. Instead the 'drvUser' string at the end of the INP or OUT field is used to distinguish the parameter to be read or written.

Service Request (SRQ) handling

The presence of one or more records with INP="@asyn(port, 0, 0) SRQ") will cause the driver to create an extra thread to read from the device Interrupt-In endpoint. The SCAN field must be "I/O Intr". Record processing will occur when the device sends a service request message on the Interrupt-In endpoint and the value will be the device status byte sent as part of the service request message. Typically the record type will be longin or mbbiDirect.

Device Status Byte (STB)

The USBTMC/USB488 device status byte is read by a record with

INP="@asyn(port, 0, 0) STB").

Typically the record type will be longin or mbbiDirect.

Remote Enable (REN)

The device remote enable is written by a record with

OUT="@asyn(port, 0, 0) REN") 

Typically the record type will be bo.

Linux udev configuration

If attempts to communicate with a device result in error messages of the form "Access denied (insufficient permissions)" you must add udev entries to allow access. In the /etc/udev/rules.d directory create a file, 55-usbtmc.rules for example, with a line for each device of interest.

To allow everyone in the "usbtmc" group access to a device with vendor code 1BFA (hexadecimal) and product code 0498 (hexadecimal) the line would look like:

SUBSYSTEM=="usb", ATTRS{idVendor}=="1BFA", ATTRS{idProduct}=="0498", GROUP="usbtmc", MODE="0660"

To allow everyone access the line would look like:

SUBSYSTEM=="usb", ATTRS{idVendor}=="1BFA", ATTRS{idProduct}=="0498", MODE="0666"

The {idVendor} and {idProduct} values must match those of the device with which you wish to communicate.

StreamDevice Exception Handlers

The USBTMC driver attempts to take correct action when it detects that the device has been unplugged or become unresponsive. The effectiveness of this depends somewhat on the level of support provided by the underlying operating system so it is good practice to also specify the following StreamDevice global exception handlers:

    @mismatch { disconnect; }
    @writetimeout { disconnect; }
    @readtimeout { disconnect; }
    @replyTimeout { disconnect; }

Additional Drivers

The drivers noted above are included as part of the ASYN distribution.  Additional drivers are available, including:


asynPortDriver C++ base class

A C++ base class called asynPortDriver is available. This is a base class from which real asyn port drivers can be derived. It greatly simplifies the job of writing an asyn port driver, because it takes care of all of the tasks like registering the port, registering the interfaces, and calling interrupt clients. It is documented separately in asynPortDriver.html.


asynPortClient C++ classes

asynPortClient is a set of C++ classes that are designed to simplify the task of writing a client that directly communicates with an asyn port driver, without running an EPICS IOC. They handle the details of connecting to the driver, finding the required interfaces, etc. They only uses the synchronous interfaces, so all calls are blocking. If clients need asynchronous operation then they can use the normal C interface with pasynManager->queueRequest. It is documented separately in asynPortClient.html.


Diagnostic Aids

iocsh Commands

    asynReport(level,portName)
    asynInterposeFlushConfig(portName,addr,timeout)
    asynInterposeEosConfig(portName,addr,processIn,processOut)
    asynSetTraceMask(portName,addr,mask)
    asynSetTraceIOMask(portName,addr,mask)
    asynSetTraceInfoMask(portName,addr,mask)
    asynSetTraceFile(portName,addr,filename)
    asynSetTraceIOTruncateSize(portName,addr,size)
    asynSetOption(portName,addr,key,val)
    asynShowOption(portName,addr,key)
    asynAutoConnect(portName,addr,yesNo)
    asynSetAutoConnectTimeout(timeout)
    asynWaitConnect(portName, timeout)
    asynEnable(portName,addr,yesNo)
    asynOctetConnect(entry,portName,addr,timeout,buffer_len,drvInfo)
    asynOctetRead(entry,nread)
    asynOctetWrite(entry,output)
    asynOctetWriteRead(entry,output,nread)
    asynOctetFlush(entry)
    asynOctetSetInputEos(portName,addr,eos,drvInfo)
    asynOctetGetInputEos(portName,addr,drvInfo)
    asynOctetSetOutputEos(portName,addr,eos,drvInfo)
    asynOctetGetOutputEos(portName,addr,drvInfo)
    asynRegisterTimeStampSource(portName,functionName);
    asynUnregisterTimeStampSource(portName)    
    

asynReport calls asynCommon:report for a specific port if portName is specified, or for all registered drivers and interposeInterface if portName is not specified.

asynInterposeFlushConfig is a generic interposeInterface that implements flush for low level drivers that don't implement flush. It just issues read requests until no bytes are left to read. The timeout is used for the read requests.

asynInterposeEosConfig is a generic interposeInterface that implements End of String processing for low level drivers that don't.

asynSetTraceMask calls asynTrace:setTraceMask for the specified port and address. If portName is zero length then the global trace mask is set.

asynSetTraceIOMask calls asynTrace:setTraceIOMask for the specified port and address. If portName is zero length then the global traceIO mask is set.

asynSetTraceInfoMask calls asynTrace:setTraceInfoMask for the specified port and address. If portName is zero length then the global traceInfo mask is set.

asynSetTraceFile calls asynTrace:setTraceFile. The filename is handled as follows:

asynSetTraceIOTruncateSize calls asynTrace:setTraceIOTruncateSize

asynSetOption calls asynCommon:setOption. asynShowOption calls asynCommon:getOption.

Thw asynOctetXXX commands provide shell access to asynOctetSyncIO methods. The entry is a character string constant that identifys the port,addr.

where

The commands asynOctetConnect, asynOctetDisconnect, asynOctetRead, asynOctetWrite, asynOctetWriteRead, asynOctetFlush allow I/O to a device from the ioc shell. Examples are:

asynOctetConnect("myid","A",0,1,20)
asynOctetWrite("myid","testnew")
asynOctetRead("myid")
testnew\n
asynOctetWriteRead("myid","this is test")
this is test\n
asynOctetDisconnect("myid")

asynRegisterTimeStampSource calls pasynManager->registerTimeStampSource for the specified port. The time stamp source function must be defined as a "function" in the application dbd file.

asynUnregisterTimeStampSource calls pasynManager->runegisterTimeStampSource for the specified port. This reverts to the default timestamp source function in asynManager.


Install and Build

Install and Build asynDriver

After obtaining a copy of the distribution, it must be installed and built for use at your site. These steps only need to be performed once for the site (unless versions of the module running under different releases of EPICS and/or the other required modules are needed).

  1. Create an installation directory for the module, usually this will end with
    .../support/asyn/
  2. Place the distribution file in this directory. Then issue the commands (Unix style)
    gunzip <file>.tar.gz
    tar xvf <file>.tar
  3. This creates a support <top>.
    .../support/asyn/X-Y
    where X-Y is the release number. For example:
    .../support/asyn/3-1
  4. Edit the config/RELEASE file and set the paths to your installation of EPICS_BASE and IPAC. IPAC is only needed if you are building for vxWorks.
  5. Run make in the top level directory and check for any compilation errors.

Using asynDriver Components with an EPICS iocCore Application

Since asynDriver does NOT provide support for specific devices an application must obtain device specific support elsewhere. This section only explains how to include asynDriver components.

In the configure/RELEASE file add definitions for IPAC, ASYN, and EPICS_BASE.

In the src directory where the application is built:

In the st.cmd file add:

dbLoadRecords("db/asynRecord.db", "P=<ioc>, R=<record>, PORT=<port>, ADDR=<addr>, OMAX=<omax>, IMAX=<imax>")

You must provide values for <ioc>, <record>, <port>, <addr>, <omax>, and <imax>.

Once the application is running, medm displays for an ioc can be started by: medm -x -macro "P=<ioc>,R=<record>" <asyntop>/medm/asynRecord.adl &

You must provide correct values for <ioc> and <record>. Once asynRecord is started, it can be connected to different devices.


License Agreement

Copyright (c) 2002 University of Chicago All rights reserved.
asynDriver is distributed subject to the following license conditions:

SOFTWARE LICENSE AGREEMENT
Software: asynDriver

 1. The "Software", below, refers to asynDriver (in either source code, or
    binary form and accompanying documentation). Each licensee is
    addressed as "you" or "Licensee."

 2. The copyright holders shown above and their third-party licensors
    hereby grant Licensee a royalty-free nonexclusive license, subject to
    the limitations stated herein and U.S. Government license rights.

 3. You may modify and make a copy or copies of the Software for use
    within your organization, if you meet the following conditions:
      a. Copies in source code must include the copyright notice and this
         Software License Agreement.
      b. Copies in binary form must include the copyright notice and this
         Software License Agreement in the documentation and/or other
         materials provided with the copy.

 4. You may modify a copy or copies of the Software or any portion of it,
    thus forming a work based on the Software, and distribute copies of
    such work outside your organization, if you meet all of the following
    conditions:
      a. Copies in source code must include the copyright notice and this
         Software License Agreement;
      b. Copies in binary form must include the copyright notice and this
         Software License Agreement in the documentation and/or other
         materials provided with the copy;
      c. Modified copies and works based on the Software must carry
         prominent notices stating that you changed specified portions of
         the Software.

 5. Portions of the Software resulted from work developed under a U.S.
    Government contract and are subject to the following license: the
    Government is granted for itself and others acting on its behalf a
    paid-up, nonexclusive, irrevocable worldwide license in this computer
    software to reproduce, prepare derivative works, and perform publicly
    and display publicly.

 6. WARRANTY DISCLAIMER. THE SOFTWARE IS SUPPLIED "AS IS" WITHOUT WARRANTY
    OF ANY KIND. THE COPYRIGHT HOLDERS, THEIR THIRD PARTY LICENSORS, THE
    UNITED STATES, THE UNITED STATES DEPARTMENT OF ENERGY, AND THEIR
    EMPLOYEES: (1) DISCLAIM ANY WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
    BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE, TITLE OR NON-INFRINGEMENT, (2) DO NOT ASSUME
    ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY, COMPLETENESS,
    OR USEFULNESS OF THE SOFTWARE, (3) DO NOT REPRESENT THAT USE OF THE
    SOFTWARE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS, (4) DO NOT WARRANT
    THAT THE SOFTWARE WILL FUNCTION UNINTERRUPTED, THAT IT IS ERROR-FREE
    OR THAT ANY ERRORS WILL BE CORRECTED.

 7. LIMITATION OF LIABILITY. IN NO EVENT WILL THE COPYRIGHT HOLDERS, THEIR
    THIRD PARTY LICENSORS, THE UNITED STATES, THE UNITED STATES DEPARTMENT
    OF ENERGY, OR THEIR EMPLOYEES: BE LIABLE FOR ANY INDIRECT, INCIDENTAL,
    CONSEQUENTIAL, SPECIAL OR PUNITIVE DAMAGES OF ANY KIND OR NATURE,
    INCLUDING BUT NOT LIMITED TO LOSS OF PROFITS OR LOSS OF DATA, FOR ANY
    REASON WHATSOEVER, WHETHER SUCH LIABILITY IS ASSERTED ON THE BASIS OF
    CONTRACT, TORT (INCLUDING NEGLIGENCE OR STRICT LIABILITY), OR
    OTHERWISE, EVEN IF ANY OF SAID PARTIES HAS BEEN WARNED OF THE
    POSSIBILITY OF SUCH LOSS OR DAMAGES.