The stringout record is used to write an arbitrary ASCII string of up to 40 characters to other records or software variables.
The record-specific fields are described below, grouped by functionality.
The string output record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in "Scan Fields". In addition, "Scanning Specification" explains how these fields are used.
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 location field (DOL) which can be either a database link or a channel access link.
DOL can also be a constant in addition to a link, in which case VAL is initialized to the constant value. However, your string constant may be interpreted as a CA link name, so if you want to initialize your string output record, it's best to use the VAL field. Note that if DOL is a constant, OMSL cannot be closed_loop. See "Address Specification" for information on specifying links.
Field Summary Type DCT Default Read Write CA PP VAL Current Value STRING [40] Yes Yes Yes Yes DOL Desired Output Loc INLINK Yes Yes Yes No OMSL Output Mode Select MENU (menuOmsl) Yes Yes Yes No
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. See "Address Specification" for information on specifying links.
In addition, the appropriate device support module must be entered into the DTYP field.
Field Summary Type DCT Default Read Write CA PP OUT Output Specification OUTLINK Yes Yes Yes No DTYP Device Type DEVICE Yes Yes Yes No
These parameters are used to specify when the monitor post should be sent by monitor() routine. There are two possible choices:
Index Identifier Choice 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.
Field Summary Type DCT Default Read Write CA PP MPST Post Value Monitors MENU (stringoutPOST) Yes Yes Yes No APST Post Archive Monitors MENU (stringoutPOST) Yes Yes Yes No
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.
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
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. There are three possible actions:
Index Identifier Choice String 0 menuIvoaContinue_normally Continue normally 1 menuIvoaDon_t_drive_outputs Don't drive outputs 2 menuIvoaSet_output_to_IVOV Set output to IVOV
When Set output to IVOV, the value contained in the IVOV field is written to the output link during an alarm condition. See "Invalid Alarm Output Action" for more information on the IVOA and IVOV fields. "Alarm Fields" lists other fields related to a alarms that are common to all record types.
Field Summary Type DCT Default Read Write CA PP IVOA INVALID output action MENU (menuIvoa) Yes Yes Yes No IVOV INVALID output value STRING [40] Yes Yes Yes No
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.
Field Summary Type DCT Default Read Write CA PP OVAL Previous Value STRING [40] No Yes No No
The following fields are used to operate the string output in the simulation mode. See "Simulation Mode" for more information on these fields.
Field Summary Type DCT Default Read Write CA PP SIOL Sim Output Specifctn OUTLINK Yes Yes Yes No SIML Sim Mode Location INLINK Yes Yes Yes No SIMM Simulation Mode MENU (menuYesNo) No Yes Yes No SIMS Sim mode Alarm Svrty MENU (menuAlarmSevr) Yes Yes Yes No
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".
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 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.
Check severity and write the new value. See "Simulation Mode" and "Invalid Alarm Output Action" for details on how the simulation mode and the INVALID alarm conditions affect output.
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 OVAL is not equal to VAL.
NSEV and NSTA are reset to 0.
Scan forward link if necessary, set PACT FALSE, and return.
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:
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 NSEV New Alarm Severity MENU (menuAlarmSevr) No Yes No No NSTA New Alarm Status MENU (menuAlarmStat) No Yes No No VAL Current Value STRING [40] Yes Yes Yes Yes OUT Output Specification OUTLINK Yes Yes Yes No
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:
0: Success.
Other: Error.
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.