Previous Chapter Chapter 23: mbboDirect - MultiBit Binary Output Direct

Chapter 23: mbboDirect - MultiBit Binary Output Direct

Continuous Electron Beam Accelerator Facility

Southeastern Universities Research Association

1. Introduction

The mbboDirect record performs the opposite function to that of the mbbiDirect record. It accumulates bits (in the fields B0 - BF) as unsigned characters, and converts them to a word which is then written out to hardware. If a bit field is non-zero, it is interpreted as a binary one. On the other hand, if it is zero, it is interpreted as a binary zero.

2. Field Summary

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

3. Field Descriptions

-----------------------------------------------------------------------------------------------
Name Summary Description
-----------------------------------------------------------------------------------------------
VAL Value Field This is the value to be sent to OUT.
DOL Desired Output If DOL is a database or channel access link and OMSL is
Location (Input CLOSED_LOOP, then VAL is read from DOL.
Link)
OMSL Output Mode Select This field has either the value SUPERVISORY or
CLOSED_LOOP. DOL is used to determine VAL only if
OMSL has the value CLOSED_LOOP. By setting this field,
the record can be switched between supervisory and
closed loop mode of operation. While in closed loop
mode, the VAL field cannot be set via dbPuts.
NOBT Number of Bits Number of bits in hardware mask.
OUT Output Link This field is used by the device support routines to decide
where to send output. For soft records, it can be a
constant, a database link, or a channel access link. If the
link is a constant, the result is no output.
B0,...,BF Bit 0 Value, Bit 1 Each represents a bit of the word to be output.
Value, ...
RVAL Raw Data Value RVAL is the value to be written to the hardware device. It
is determined by the record support module using VAL as
the bit values stored in B0,...BF. The value is also shifted
left SHFT bits.
ORAW Old Raw Data ORAW is used to decide if monitors should be triggered for
Value RVAL at the same time monitors are generated for changes
in VAL.
RBV Read Back Value This is the actual read back value obtained from the
hardware itself or from the associated device driver. It is
the responsibility of the device support routine to give this
field a value
ORBV Old Read Back ORBV is used to decide if monitors should be triggered for
Value RBV 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.
MLST Monitor Last Value when last monitor for value changes was triggered.
LALM Last Alarmed Value when last change of state alarm was issued.
SHFT Shift Number of bits to shift values obtained from VAL.
SIMM Simulation Mode Simulation mode process variables. Refer to Chapter 3,
Section "Simulation Mode" on page 13 for more
information.
SIML Simulation Mode
Location
SIOL Simulation Value
Location
SIMS Simulation Mode
Alarm Severity
IVOA Invalid Alarm Whenever the record is put into INVALID alarm severity
Output Action IVOA specifies an action. See Chapter 3, Section "Invalid
Alarm Output Action" on page 14 for more information
IVOV Invalid Alarm
Output Value
-----------------------------------------------------------------------------------------------

4. Record Support Routines

init_record

This routine initializes SIMM if SIML is a constant or creates a channel access link if SIML is PV_LINK. If SIOL is PV_LINK a channel access link is created.

This routine next checks to see that device support is available.The routine next checks to see if the device support write routine is defined. If either device support or the device support write routine does not exist, an error message is issued and processing is terminated.

If DOL is a constant, then VAL is initialized to its value and UDF is set to FALSE.

MASK is cleared and then the NOBT low order bits are set.

If device support includes init_record, it is called.

init_common is then called to determine if any states are defined. If states are defined, SDEF is set to TRUE.

If device support returns success, VAL is then set from RVAL and UDF is set to FALSE.

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.
If PACT is FALSE
- If DOL is DB_LINK and OMSL is CLOSED_LOOP
  - Get value from DOL
  - Set PACT to FALSE
Convert
- If PACT is FALSE, compute RVAL
  - Set RVAL = VAL
  - Shift RVAL left SHFT bits
- Status=write_mbboDirect
If PACT has been changed to TRUE, the device support write output routine has started but has not completed writing the new value. In this case, the processing routine merely returns, leaving PACT TRUE.
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 and RBV 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 mbboDirect record must have an associated set of device support routines. The primary responsibility of the device support routines is to obtain a new raw mbbo value whenever write_mbboDirect 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.                                                  
OUT   Output Link         This field is used by the device support routines to locate   
                          its output.                                                   
RVAL  Raw data value      This is the value to be written to OUT.                       
RBV   Read Back Value      It is the responsibility of the device support modules to    
                          set this field.                                               
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 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 MASK is used, it should be shifted if necessary and SHFT given 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.

write_mbboDirect

  write_mbboDirect(precord)

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

0: Success.
Other: Error.

7. Device Support For Soft Records

This module writes the current value of VAL.

If the OUT link type is PV_LINK, then dbCaAddInlink is called by init_record.

write_mbboDirect calls recGblPutLinkValue to write the current value of VAL. See Chapter 3, Section "Soft Output" on page 13 for details.

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