Long Output Record (longout)

The normal use for the long output or "longout" record type is to store long integer values of up to 32 bits and write them to hardware devices. The Soft Channel device support layer can also be used to write values to other records via database or channel access links. The OUT field determines how the record is used. The record supports alarm limits and graphics and control limits.

Parameter Fields

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

Scan Parameters

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

Desired Output Parameters

The record must specify where the desired output originates, i.e., the 32 bit integer value it is to write. The output mode select (OMSL) field determines whether the output originates from another record or from database access. When set to closed_loop, the desired output is retrieved from the link specified in the desired output (DOL) field (which can specify either a database or channel access link) and placed into the VAL field. When set to supervisory, the desired output can be written into the VAL field via dpPuts at run-time.

A third type of value for the DOL field is a constant in which case, when the record is initialized, the VAL field will be initialized with this constant value.

The VAL field's value will be clipped within limits specified in the fields DRVH and DRVL if these have been configured by the database designer:


Note: These limits are only enforced as long as DRVH > DRVL. If they are not set or DRVH <= DRVL they will not be used.

FieldSummaryTypeDCT DefaultReadWriteCA PP
DOLDesired Output LocINLINKYes YesYesNo
OMSLOutput Mode SelectMENU (menuOmsl)Yes YesYesNo
DRVHDrive High LimitLONGYes YesYesYes
DRVLDrive Low LimitLONGYes YesYesYes
VALDesired OutputLONGYes YesYesYes

Write Parameters

The OUT link field determines where the record is to send its output. For records that write values to hardware devices, the OUT output link field must specify the address of the I/O card, and the DTYP field must specify the name of the corresponding device support module.

For soft records, the OUT output link can be a constant, a database link, or a channel access link. If the link is a constant, the result is no output. The DTYP field must then specify the Soft Channel device support routine.

See "Address Specification" for information on the format of hardware addresses and database links.

FieldSummaryTypeDCT DefaultReadWriteCA PP
OUTOutput SpecificationOUTLINKYes YesYesNo
DTYPDevice TypeDEVICEYes YesYesNo

Operator Display Parameters

These parameters are used to present meaningful data to the operator. They display the value and other parameters of the long output either textually or graphically.

EGU is a string of up to 16 characters describing the units that the long output measures. It is retrieved by the get_units record support routine.

The HOPR and LOPR fields set the upper and lower display limits for the VAL, HIHI, HIGH, LOW, and LOLO fields. Both the get_graphic_double and get_control_double record support routines retrieve these fields.

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

FieldSummaryTypeDCT DefaultReadWriteCA PP
EGUEngineering UnitsSTRING [16]Yes YesYesNo
HOPRHigh Operating RangeLONGYes YesYesNo
LOPRLow Operating RangeLONGYes YesYesNo
NAMERecord NameSTRING [61]No YesNoNo
DESCDescriptorSTRING [41]Yes YesYesNo

Alarm Parameters

The possible alarm conditions for long inputs are the SCAN, READ, INVALID, and limit alarms. The SCAN and READ alarms are not configurable by the user because their severity is always MAJOR. The INVALID alarm is called by the record support routine when the record or device support routines cannot write the record's output. The IVOA field specifies the action to take in this case.

The limit alarms are configured by the user in the HIHI, LOLO, HIGH, and LOW fields using floating-point values. For each of these fields, there is a corresponding severity field which can be either NO_ALARM, MINOR, or MAJOR. The HYST field contains the alarm deadband around each limit alarm.

See "Alarm Specification" for a complete explanation of alarms and these fields. For an explanation of the IVOA and IVOV fields, see "Output Records". Alarm Fields lists the fields related to alarms that are common to all record types.

FieldSummaryTypeDCT DefaultReadWriteCA PP
HIHIHihi Alarm LimitLONGYes YesYesYes
HIGHHigh Alarm LimitLONGYes YesYesYes
LOWLow Alarm LimitLONGYes YesYesYes
LOLOLolo Alarm LimitLONGYes YesYesYes
HHSVHihi SeverityMENU (menuAlarmSevr)Yes YesYesYes
HSVHigh SeverityMENU (menuAlarmSevr)Yes YesYesYes
LSVLow SeverityMENU (menuAlarmSevr)Yes YesYesYes
LLSVLolo SeverityMENU (menuAlarmSevr)Yes YesYesYes
HYSTAlarm DeadbandLONGYes YesYesNo
IVOAINVALID output actionMENU (menuIvoa)Yes YesYesNo
IVOVINVALID output valueLONGYes YesYesNo

Monitor Parameters

These parameters are used to determine when to send monitors placed on the value field. The monitors are sent when the value field exceeds the last monitored field by the appropriate delta. If these fields have a value of zero, everytime the value changes, a monitor will be triggered; if they have a value of -1, everytime the record is scanned, monitors are triggered. The ADEL field is the delta for archive monitors, and the MDEL field is the delta for all other types of monitors. See "Monitor Specification" for a complete explanation of monitors.

FieldSummaryTypeDCT DefaultReadWriteCA PP
ADELArchive DeadbandLONGYes YesYesNo
MDELMonitor DeadbandLONGYes YesYesNo

Run-time Parameters

The LALM, MLST, and ALST fields are used to implement the hysteresis factors for monitor callbacks. Only if the difference between these fields and the corresponding value field is greater than the appropriate delta (MDEL, ADEL, HYST)--only then are monitors triggered. For instance, only if the difference between VAL and MLST is greater than MDEL are the monitors triggered for VAL.

FieldSummaryTypeDCT DefaultReadWriteCA PP
LALMLast Value AlarmedLONGNo YesNoNo
ALSTLast Value ArchivedLONGNo YesNoNo
MLSTLast Val MonitoredLONGNo YesNoNo

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. 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.

FieldSummaryTypeDCT DefaultReadWriteCA PP
SIMLSim Mode LocationINLINKYes YesYesNo
SIMMSimulation ModeMENU (menuYesNo)No YesYesNo
SIOLSim Output SpecifctnOUTLINKYes YesYesNo
SIMSSim mode Alarm SvrtyMENU (menuAlarmSevr)Yes YesYesNo
SDLYSim. Mode Async DelayDOUBLEYes-1.0YesYesNo
SSCNSim. Mode ScanMENU (menuScan)Yes65535YesYesNo

Record Support

Record Support Routines


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. If DOL type is a PV_LINK then dbCaAddInlink is called to create a channel access link.

If device support includes init_record(), it is called.


See next section.


Retrieves EGU.


Sets the upper display and lower display limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.


Sets the upper control and the lower control limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.


Sets the following values:

   upper_alarm_limit = HIHI
   upper_warning_limit = HIGH
   lower_warning_limit = LOW
   lower_alarm_limit = LOLO

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 and OMSL is CLOSED_LOOP recGblGetLinkValue is called to read the current value of VAL. See "Output Records" for more information. If the return status of recGblGetLinkValue is zero then UDF is set to FALSE.
  3. Check alarms. This routine checks to see if the new VAL causes the alarm status and severity to change. If so, NSEV, NSTA and LALM are set. It also honors the alarm hysteresis factor (HYST). Thus the value must change by more than HYST before the alarm status and severity is lowered.
  4. Check severity and write the new value. See Invalid Output Action Fields for information on how INVALID alarms affect output records.
  5. 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.
  6. 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 ADEL and MDEL conditions are met.
    • NSEV and NSTA are reset to 0.
  7. Scan forward link if necessary, set PACT FALSE, and return.

Device Support

Fields Of Interest To Device Support

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

FieldSummaryTypeDCT DefaultReadWriteCA PP
PACTRecord activeUCHARNo YesNoNo
NSEVNew Alarm SeverityMENU (menuAlarmSevr)No YesNoNo
NSTANew Alarm StatusMENU (menuAlarmStat)No YesNoNo
OUTOutput SpecificationOUTLINKYes YesYesNo

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.



This routine is optional. If provided, it is called by the record support init_record() routine.


  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:

Device Support For Soft Records

The 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_longout calls recGblPutLinkValue to write the current value of VAL.

See "Soft Output" for a further explanation.