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.
The record-specific fields are described below, grouped by functionality.
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  Yes Yes Yes No PRIO Scheduling Priority MENU (menuPriority) Yes Yes Yes No PINI Process at iocInit MENU (menuPini) Yes Yes Yes No
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
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
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
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
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
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
which could cause problems with some client programs.
Prior to the EPICS 188.8.131.52 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
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 184.108.40.206 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
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.
Soft Channel support writes the contents of the VAL field to the output link.
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
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  No Yes No No DESC Descriptor STRING  Yes Yes Yes No
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
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. 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 (menuYesNo) 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
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:
Don't drive outputs,
Set output to IVOV.
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.
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
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
it is called.
If device support returns success, VAL is then set from RVAL and UDF is set to FALSE.
See next section.
Routine process implements the following algorithm:
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 consists of the following routines:
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.
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.
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,
after set to 1.
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(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.
This routine must output a new value. It returns the following values:
SOft Channel module writes the current value of VAL.
If the OUT link type is PV_LINK, then dbCaAddInlink is called by
write_mbboDirect calls recGblPutLinkValue to write the current value of VAL.
See Soft Output.