Previous Chapter Chapter 22: mbbiDirect - MultiBit Binary Input Direct

Chapter 22: mbbiDirect - MultiBit Binary Input Direct

Continuous Electron Beam Accelerator Facility

Southeastern Universities Research Association

1. Introduction

The mbbiDirect record retrieves a sixteen bit hardware value and converts it to an array of sixteen unsigned characters, each representing a bit of the word. These fields (B0-B15) are set to one if a bit is set, and zero if not. This record's operation is similar to that of an mbbi, and it has many fields in common with it.

2. Field Summary

--------------------------------------------------------------
Field  Type       DCT  Initial  Access  Modify  Rec Proc   PP   
                                                Monitor         
--------------------------------------------------------------
VAL    USHORT     No   0        Yes     No      Yes        Yes  
NOBT   SHORT      Yes  0        Yes     No                 No   
INP    INLINK     Yes  0        No      No      N/A        No   
RVAL   ULONG      No   0        Yes     Yes     Yes        Yes  
ORAW   ULONG      No   0        Yes     No      No         No   
MASK   ULONG      No   0        Yes     No      No         No   
MLST   USHORT     No   0        Yes     No      No         No   
LALM   USHORT     No   0        Yes     No      No         No   
SDEF   SHORT      No   0        Yes     No      No         No   
SHFT   USHORT     No   0        Yes     No      No         No   
SIOL   INLINK     Yes  0        No      No      No         No   
SVAL   USHORT     No   0        Yes     Yes     No         No   
SIML   INLINK     Yes  0        No      No      No         No   
SIMM   GBLCHOICE  No   0        Yes     Yes     No         No   
SIMS   GBLCHOICE  Yes  0        Yes     Yes     No         No   
B0     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B1     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B2     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B3     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B4     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B5     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B6     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B7     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B8     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
B9     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BA     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BB     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BC     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BD     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BE     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
BF     UCHAR      Yes  0        Yes     Yes     Yes        Yes  
--------------------------------------------------------------

3. Field Descriptions

----------------------------------------------------------------------------------------------
Name         Summary              Description                                                   
----------------------------------------------------------------------------------------------
VAL          Value Field          Unless INP is a constant link, this is the value resulting    
                                  from the record being processed. If INP is a constant, then   
                                  VAL is initialized to the INP value but can be changed        
                                  dynamically via dbPutField or dbPutLink.                      
NOBT         Number of Bits       Number of bits set in hardware mask.                          
INP          Input Link           This field is used by the device support routines to obtain   
                                  input. For soft records, it can be a constant, a database     
                                  link, or a channel access link.                               
B0, ..., BF  Bit 0 Value, Bit 1   Each represents a bit of the word.                            
             Value ...                                                                          
RVAL         Raw Data Value       RVAL is the value obtained by the device support routine.     
                                  Unless the device support routine specifies no conversion,    
                                  VAL is determined as follows: A temporary variable rval       
                                  is set equal to RVAL.                                         
ORAW         Old Raw Data         ORAW is used to decide if monitors should be triggered for    
             Value                RVAL at the same time monitors are triggered for changes      
                                  in VAL.                                                       
MASK         Mask                 Mask used by device support routine to read hardware          
                                  register. Record support sets low order NOBT bits. Device     
                                  support can shift this value.                                 
SHFT         Shift                Number of bits to shift values obtained from RVAL.            
LALM         Last Alarmed         Value when last change of state alarm was issued.             
MLST         Monitor Last         Value when last monitor for value changes was triggered.      
SDEF         States Defined                                                                     
SIMM         Simulation Mode      Simulation mode process variables.  Refer to Chapter 3,       
                                  Section "Simulation Mode" on page 11 for more                 
                                  information.                                                  
SIML         Simulation Mode                                                                    
             Location                                                                           
SVAL         Simulation Value                                                                   
SIOL         Simulation Value                                                                   
             Location                                                                           
SIMS         Simulation Mode                                                                    
             Alarm Severity                                                                     
----------------------------------------------------------------------------------------------

4. Record Support Routines

init_record

This routine initializes SIMM with the value of SIML if SIML type is CONSTANT link or creates a channel access link if SIML type is PV_LINK. SVAL is likewise initialized if SIOL is CONSTANT or PV_LINK.

This routine next checks to see that device support is available and a device support read routine is defined. If either does not exist, an error message is issued and processing is terminated.

Clears MASK and then sets the NOBT low order bits.

If device support includes init_record, it is called.

refresh_bits is then called to refresh all the bit fields based on a hardware value.

process

See next section.

get_value

Fills in the values of struct valueDes so that they refer to VAL.

5. Record Processing

Routine process implements the following algorithm:

Check to see that the appropriate device support module exists. If it doesn't, an error message is issued and processing is terminated with the PACT field still set to TRUE. This ensures that processes will no longer be called for this record. Thus error storms will not occur.
readValue is called. See Chapter 3, Section "Simulation Mode" on page 11 for details.
If PACT has been changed to TRUE, the device support read routine has started but has not completed reading a new input value. In this case, the processing routine merely returns, leaving PACT TRUE.
Convert.
- status=read_mbbiDirect
- PACT = TRUE
- TIME = tsLocalTime
- If status is 0, then determine VAL
  - Set rval = RVAL
  - Shift rval right SHFT bits
  - Set VAL = RVAL
  - If status is 1, return(0)
- If status is 2, set status = 0
Check to see if monitors should be invoked.
- Alarm monitors are invoked if the alarm status or severity has changed.
- Archive and value change monitors are invoked if MLST is not equal to VAL.
- Monitors for RVAL are checked whenever other monitors are invoked.
- NSEV and NSTA are reset to 0.
Scan forward link if necessary, set PACT FALSE, and return.

6. Device Support

Fields Of Interest To Device Support

Each input record must have an associated set of device support routines. The primary responsibility of the device support routines is to obtain a new raw input value whenever read_mbbiDirect is called. The device support routines are primarily interested in the following fields:

-----------------------------------------------------------------------------------------
Name  Summary             Description                                                      
-----------------------------------------------------------------------------------------
PACT  Processing Active   See Chapter 2, Section "Database Common: Field                   
                          Descriptions" on page 4 for descriptions.                        
DPVT  Device Private                                                                       
UDF   VAL Undefined                                                                        
NSEV  New Alarm Severity                                                                   
NSTA  New Alarm Status                                                                     
NOBT  Number of Bits      Number of hardware bits accessed. They must be                   
                          consecutive.                                                     
VAL   Value Field         This field is set by the device support routines if they         
                          don't want record support to set it.                             
INP   Input Link          This field is used by the device support routines to locate      
                          its input.                                                       
RVAL  Raw Data Value      It is the responsibility of the device support routine to give   
                          this field a value.                                              
MASK  Mask                This is a mask used to read the hardware. Record support         
                          sets the low order NOBT bits. The device support routine         
                          can shift the bits. The device support routine should            
                          perform the shift in init_record.                                
SHFT  Shift               This can be set by the device support module at                  
                          init_record time.                                                
-----------------------------------------------------------------------------------------

Device Support Routines

Device support consists of the following routines:

report

  report(FILE fp, paddr)

Not currently used.

init

  init()

This routine is called once during IOC initialization.

init_record

  init_record(precord)

This routine is optional. If provided, it is called by the record support init_record routine. If it uses MASK, it should shift it as necessary and also give SHFT a value.

get_ioint_info

  get_ioint_info(int cmd,struct dbCommon *precord,IOSCANPVT *ppvt)

This routine is called by the ioEventScan system each time the record is added or deleted from an I/O event scan list. cmd has the value (0,1) if the record is being (added to, deleted from) an I/O event list. It must be provided for any device type that can use the ioEvent scanner.

read_mbbiDirect

  read_mbbiDirect(precord)

This routine must provide a new input value. It returns the following values:

0: Success. A new raw value is placed in RVAL. The record support module determines VAL from RVAL and SHFT.
2: Success, but don't modify VAL.
Other: Error.

7. Device Support For Soft Records

Two soft device support modules Soft Channel and Raw Soft Channel are provided for multibit binary input direct records not related to actual hardware devices. The INP link type must be either CONSTANT, DB_LINK, or CA_LINK.

Soft Channel

read_mbbiDirect always returns a value of 2, which means that no conversion is performed.

If the INP link type is constant, then the constant value is stored into VAL by init_record, and UDF is set to FALSE. VAL can be changed via dbPut requests. If the INP link type is PV_LINK, then dbCaAddInlink is called by init_record.

read_mbbiDirect calls recGblGetLinkValue to read the current value of VAL. See Chapter 3, Section "Soft Input" on page 10 for details.

If the return status of recGblGetLinkValue is zero, then read_mbbi sets UDF to FALSE. The status of recGblGetLinkValue is returned.

Raw Soft Channel

This module is like the previous except that values are read into RVAL, VAL is computed from RVAL, and read_mbbiDirect returns a value of 0. Thus the record processing routine will determine VAL in the normal way.

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