String Output Record (stringout)

The stringout record is used to write an arbitrary ASCII string of up to 40 characters to other records or software variables.

Parameter Fields

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

Scan Parameters

The string output 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 string output record must specify from where it gets its desired output string. The first field that determines where the desired output originates is the output mode select (OMSL) field, which can have two possible value: closed_loop or supervisory. If supervisory is specified, DOL is ignored, the current value of VAL is written, and the VAL can be changed externally via dbPuts at run-time. If closed_loop is specified, the VAL field's value is obtained from the address specified in the Desired Output Link field (DOL) which can be either a database link or a channel access link.

DOL can also be a constant, in which case VAL will be initialized to the constant value. However to be interpreted as a constant instead of a CA link the constant can only be numeric, so string output records are best initialized by dirctly setting the VAL field. Note that if DOL is a constant, OMSL cannot be closed_loop.

FieldSummaryTypeDCT DefaultReadWriteCA PP
VALCurrent ValueSTRING [40]Yes YesYesYes
DOLDesired Output LinkINLINKYes YesYesNo
OMSLOutput Mode SelectMENU (menuOmsl)Yes YesYesNo

Output Specification

The output link specified in the OUT field specifies where the string output record is to write its string. The link can be a database or channel access link. If the OUT field is a constant, no output will be written.

In addition, the appropriate device support module must be entered into the DTYP field.

FieldSummaryTypeDCT DefaultReadWriteCA PP
OUTOutput SpecificationOUTLINKYes YesYesNo
DTYPDevice TypeDEVICEYes YesYesNo

Monitor Parameters

These parameters are used to specify when the monitor post should be sent by monitor() routine. There are two possible choices:

Menu stringoutPOST

IndexIdentifierChoice String
0 stringoutPOST_OnChange On Change
1 stringoutPOST_Always Always

APST is used for archiver monitors and MPST is for all other type of monitors.

FieldSummaryTypeDCT DefaultReadWriteCA PP
MPSTPost Value MonitorsMENU (stringoutPOST)Yes YesYesNo
APSTPost Archive MonitorsMENU (stringoutPOST)Yes YesYesNo

Operator Display Parameters

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

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

FieldSummaryTypeDCT DefaultReadWriteCA PP
NAMERecord NameSTRING [61]No YesNoNo
DESCDescriptorSTRING [41]Yes YesYesNo

Run-time Parameters

The old value field (OVAL) of the string input is used to implement value change monitors for VAL. If VAL is not equal to OVAL, then monitors are triggered.

FieldSummaryTypeDCT DefaultReadWriteCA PP
OVALPrevious ValueSTRING [40]No 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
SIMLSimulation Mode LinkINLINKYes YesYesNo
SIMMSimulation ModeMENU (menuYesNo)No YesYesNo
SIOLSimulation Output LinkOUTLINKYes YesYesNo
SIMSSimulation Mode SeverityMENU (menuAlarmSevr)Yes YesYesNo
SDLYSim. Mode Async DelayDOUBLEYes-1.0YesYesNo
SSCNSim. Mode ScanMENU (menuScan)Yes65535YesYesNo

Alarm Parameters

The possible alarm conditions for the string output record are the SCAN, READ, and INVALID alarms. The severity of the first two is always MAJOR and not configurable.

The IVOA field specifies an action to take when the INVALID alarm is triggered. When Set output to IVOV, the value contained in the IVOV field is written to the output link during an alarm condition. See Invalid Output Action Fields for more information on the IVOA and IVOV fields.

Alarm Fields lists the fields related to alarms that are common to all record types.

FieldSummaryTypeDCT DefaultReadWriteCA PP
IVOAINVALID output actionMENU (menuIvoa)Yes YesYesNo
IVOVINVALID output valueSTRING [40]Yes YesYesNo

Record Support

Record Support Routines


  long (*init_record)(struct dbCommon *precord, int pass)

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 the type double constant, if non-zero, is converted to a string and stored into VAL 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.


  long (*process)(struct dbCommon *precord)

See "Record Processing".

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 "Soft Output". If the return status of recGblGetLinkValue is zero then UDF is set to FALSE.
  3. Check severity and write the new value. See "Simulation Mode" and Invalid Output Action Fields for details on how the simulation mode and the INVALID alarm conditions affect output.
  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 OVAL is not equal to VAL.
    • 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 stringout output record must have an associated set of device support routines. The primary responsibility of the device support routines is to write a new value whenever write_stringout 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
VALCurrent ValueSTRING [40]Yes YesYesYes
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.


  long init_record(dbCommon *prec)

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


  long get_ioint_info(int cmd, 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.


  long write_stringout(stringoutRecord *prec)

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

Device Support for Soft Records

The Soft Channel device support module writes the current value of VAL.

Device support for DTYP stdio is provided for writing values to the stdout, stderr, or errlog streams. INST_IO addressing @stdout, @stderr or @errlog is used on the OUT link field to select the desired stream.