Multi-Bit Binary Output Direct Record (mbboDirect)

The mbboDirect record performs roughly the opposite function to that of the mbbiDirect record.

It can accept boolean values in its 32 bit fields (B0-B9, BA-BF, B10-B19 and B1A-B1F), and converts them to a 32-bit signed integer in VAL which is provided to the device support. A zero value in a bit field becomes a zero bit in VAL, a non-zero value in a bit field becomes a one bit in VAL, with B0 being the least signficant bit and B1F the MSB/sign bit.

Parameter Fields

The record-specific fields are described below, grouped by functionality.

Scan Parameters

The mbboDirect record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in Scan Fields.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

SCAN

Scan Mechanism

MENU menuScan

Yes

Yes

Yes

No

PHAS

Scan Phase

SHORT

Yes

Yes

Yes

No

EVNT

Event Name

STRING [40]

Yes

Yes

Yes

No

PRIO

Scheduling Priority

MENU menuPriority

Yes

Yes

Yes

No

PINI

Process at iocInit

MENU menuPini

Yes

Yes

Yes

No

Desired Output Parameters

Like all output records, the mbboDirect record must specify where its output should originate when it gets processed. The Output Mode SeLect field (OMSL) determines whether the output value should be read from another record or not. When set to closed_loop, a 32-bit integer value (the “desired output”) will be read from a link specified in the Desired Output Link (DOL) field and placed into the VAL field.

When OMSL is set to supervisory, the DOL field is ignored during processing and the contents of VAL are used. A value to be output may thus be written direcly into the VAL field from elsewhere as long as the record is in supervisory mode.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

OMSL

Output Mode Select

MENU menuOmsl

Yes

Yes

Yes

Yes

DOL

Desired Output Link

INLINK

Yes

Yes

Yes

No

VAL

Word

LONG

Yes

Yes

Yes

Yes

Bit Fields

The fields B0 through BF and B10 through B1F provide an alternative way to set the individual bits of the VAL field when the record is in supervisory mode. Writing to one of these fields will then modify the corresponding bit in VAL, and writing to VAL will update these bit fields from that value.

The VAL field is signed so it can be accessed through Channel Access as an integer; if it were made unsigned (a DBF_ULONG) its representation through Channel Access would become a double, which could cause problems with some client programs.

Prior to the EPICS 7.0.6.1 release the individual bit fields were not updated while the record was in closed_loop mode with VAL being set from the DOL link, and writing to the bit fields in that mode could cause the record to process but the actual field values would not affect VAL at all. Changing the OMSL field from closed_loop to supervisory would set the bit fields from VAL at that time and trigger a monitor event for the bits that changed at that time. At record initialization if VAL is defined and the OMSL field is supervisory the bit fields would be set from VAL.

From EPICS 7.0.6.1 the bit fields get updated from VAL during record processing and monitors are triggered on them in either mode. Attempts to write to the bit fields while in closed_loop mode will be rejected by the special() routine which may trigger an error from the client that wrote to them. During initialization if the record is still undefined (UDF) after DOL has been read and the device support initialized but at least one of the B0-B1F fields is non-zero, the VAL field will be set from those fields and UDF will be cleared.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

B0

Bit 0

UCHAR

Yes

Yes

Yes

Yes

B1

Bit 1

UCHAR

Yes

Yes

Yes

Yes

B2

Bit 2

UCHAR

Yes

Yes

Yes

Yes

B3

Bit 3

UCHAR

Yes

Yes

Yes

Yes

B4

Bit 4

UCHAR

Yes

Yes

Yes

Yes

B5

Bit 5

UCHAR

Yes

Yes

Yes

Yes

B6

Bit 6

UCHAR

Yes

Yes

Yes

Yes

B7

Bit 7

UCHAR

Yes

Yes

Yes

Yes

B8

Bit 8

UCHAR

Yes

Yes

Yes

Yes

B9

Bit 9

UCHAR

Yes

Yes

Yes

Yes

BA

Bit 10

UCHAR

Yes

Yes

Yes

Yes

BB

Bit 11

UCHAR

Yes

Yes

Yes

Yes

BC

Bit 12

UCHAR

Yes

Yes

Yes

Yes

BD

Bit 13

UCHAR

Yes

Yes

Yes

Yes

BE

Bit 14

UCHAR

Yes

Yes

Yes

Yes

BF

Bit 15

UCHAR

Yes

Yes

Yes

Yes

B10

Bit 16

UCHAR

Yes

Yes

Yes

Yes

B11

Bit 17

UCHAR

Yes

Yes

Yes

Yes

B12

Bit 18

UCHAR

Yes

Yes

Yes

Yes

B13

Bit 19

UCHAR

Yes

Yes

Yes

Yes

B14

Bit 20

UCHAR

Yes

Yes

Yes

Yes

B15

Bit 21

UCHAR

Yes

Yes

Yes

Yes

B16

Bit 22

UCHAR

Yes

Yes

Yes

Yes

B17

Bit 23

UCHAR

Yes

Yes

Yes

Yes

B18

Bit 24

UCHAR

Yes

Yes

Yes

Yes

B19

Bit 25

UCHAR

Yes

Yes

Yes

Yes

B1A

Bit 26

UCHAR

Yes

Yes

Yes

Yes

B1B

Bit 27

UCHAR

Yes

Yes

Yes

Yes

B1C

Bit 28

UCHAR

Yes

Yes

Yes

Yes

B1D

Bit 29

UCHAR

Yes

Yes

Yes

Yes

B1E

Bit 30

UCHAR

Yes

Yes

Yes

Yes

B1F

Bit 31

UCHAR

Yes

Yes

Yes

Yes

Convert and Write Parameters

For records that are to write values to hardware devices, the OUT output link must contain the address of the I/O card, and the DTYP field must specify the proper device support module. Be aware that the address format differs according to the I/O bus used. See Address Specification for information on the format of hardware addresses.

During record processing VAL is converted into RVAL, which is the actual 32-bit word to be sent out. RVAL is set to VAL shifted left by the number of bits specified in the SHFT field (SHFT is normally set by device support). RVAL is then sent out to the location specified in the OUT field.

The fields NOBT and MASK can be used by device support to force some of the output bits written by that support to be zero. By default all 32 bits can be sent, but the NOBT field can be set to specify a smaller number of contiguous bits, or MASK can specify a non-contiguous set of bits. When setting MASK it is often necessary to set NOBT to a non-zero value as well, although in this case the actual value of NOBT may be ignored by the device support. If a device support sets the SHFT field it will also left-shift the value of MASK at the same time.

For mbboDirect records writing to a link instead of to hardware, the DTYP field must select one of the soft device support routines Soft Channel or Raw Soft Channel. The Soft Channel support writes the contents of the VAL field to the output link. The Raw Soft Channel support allows SHFT to be set in the DB file, and sends the result of ANDing the shifted MASK with the RVAL field’s value.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

OUT

Output Specification

OUTLINK

Yes

Yes

Yes

No

RVAL

Raw Value

ULONG

No

Yes

No

Yes

SHFT

Shift

USHORT

Yes

Yes

Yes

No

MASK

Hardware Mask

ULONG

No

Yes

No

No

NOBT

Number of Bits

SHORT

Yes

Yes

No

No

Operator Display Parameters

See Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

NAME

Record Name

STRING [61]

No

Yes

No

No

DESC

Descriptor

STRING [41]

Yes

Yes

Yes

No

Run-time Parameters

These parameters are used by the run-time code for processing the mbbo Direct record.

MASK is used by device support routine to read the hardware register. Record support sets the low order NOBT bits of MASK at initialization, and device support is allowed to shift this value.

MLST holds the value when the last monitor for value change was triggered. OBIT has a similar role for bits held in the B0-B1F fields.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

NOBT

Number of Bits

SHORT

Yes

Yes

No

No

ORAW

Prev Raw Value

ULONG

No

Yes

No

No

MASK

Hardware Mask

ULONG

No

Yes

No

No

MLST

Last Value Monitored

LONG

No

Yes

No

No

OBIT

Last Bit mask Monitored

LONG

No

Yes

No

No

Simulation Mode Parameters

The following fields are used to operate the record in simulation mode.

If SIMM (fetched through SIML) is YES, the record is put in SIMS severity and the value is written through SIOL, without conversion. If SIMM is RAW, the value is converted and RVAL is written. SSCN sets a different SCAN mechanism to use in simulation mode. SDLY sets a delay (in sec) that is used for asynchronous simulation processing.

See Output Simulation Fields for more information on simulation mode and its fields.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

SIML

Simulation Mode Link

INLINK

Yes

Yes

Yes

No

SIMM

Simulation Mode

MENU menuSimm

No

Yes

Yes

No

SIOL

Simulation Output Link

OUTLINK

Yes

Yes

Yes

No

SIMS

Simulation Mode Severity

MENU menuAlarmSevr

Yes

Yes

Yes

No

SDLY

Sim. Mode Async Delay

DOUBLE

Yes

-1.0

Yes

Yes

No

SSCN

Sim. Mode Scan

MENU menuScan

Yes

65535

Yes

Yes

No

Alarm Parameters

The possible alarm conditions for mbboDirect records are the SCAN, READ, and INVALID alarms.

The IVOA field specifies an action to take when an INVALID alarm is triggered. There are three possible actions: Continue normally, Don't drive outputs, or Set output to IVOV. When Set output to IVOV is specified and a INVALID alarm is triggered, the record will write the value in the IVOV field to the output.

See Invalid Output Action Fields for more information about IVOA and IVOV.

See Alarm Specification for a complete explanation of record alarms and of the standard fields. Alarm Fields lists other fields related to alarms that are common to all record types.

Field

Summary

Type

DCT

Default

Read

Write

CA PP

IVOA

INVALID outpt action

MENU menuIvoa

Yes

Yes

Yes

No

IVOV

INVALID output value

LONG

Yes

Yes

Yes

No

Record Support

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.

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

Process

See next section.

Record Processing

Routine process implements the following algorithm:

  1. 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.

  2. If PACT is FALSE

    • If DOL is DB_LINK and OMSL is CLOSED_LOOP

      • Get value from DOL

      • Set PACT to FALSE

  3. Convert

    • If PACT is FALSE, compute RVAL

      • Set RVAL = VAL

      • Shift RVAL left SHFT bits

    • Status=write_mbboDirect

  4. 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.

  5. 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.

  6. Scan forward link if necessary, set PACT FALSE, and return.




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:

Field

Summary

Type

DCT

Default

Read

Write

CA PP

PACT

Record active

UCHAR

No

Yes

No

No

DPVT

Device Private

NOACCESS

No

No

No

No

UDF

Undefined

UCHAR

Yes

1

Yes

Yes

Yes

NSEV

New Alarm Severity

MENU menuAlarmSevr

No

Yes

No

No

NSTA

New Alarm Status

MENU menuAlarmStat

No

Yes

No

No

NOBT

Number of Bits

SHORT

Yes

Yes

No

No

OUT

Output Specification

OUTLINK

Yes

Yes

Yes

No

RVAL

Raw Value

ULONG

No

Yes

No

Yes

RBV

Readback Value

ULONG

No

Yes

No

No

MASK

Hardware Mask

ULONG

No

Yes

No

No

SHFT

Shift

USHORT

Yes

Yes

Yes

No

Device Support Routines

Device support consists of the following routines:

long report(int level)

This optional routine is called by the IOC command dbior and is passed the report level that was requested by the user. It should print a report on the state of the device support to stdout. The level parameter may be used to output increasingly more detailed information at higher levels, or to select different types of information with different levels. Level zero should print no more than a small summary.

long init(int after)

This optional routine is called twice at IOC initialization time. The first call happens before any of the init_record() calls are made, with the integer parameter after set to 0. The second call happens after all of the init_record() calls have been made, with after set to 1.

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.

Device Support For Soft Records

This SOft Channel 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 Soft Output.