The string input record retrieves an arbitrary ASCII string of up to 40 characters. Several device support routines are available, all of which are soft device support for retrieving values from other records or other software components.
The record-specific fields are described below, grouped by functionality.
The string input 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 INP field determines where the string input record gets its string. It can be a database or channel access link, or a constant. If constant, the VAL field is initialized with the constant and can be changed via dbPuts. Otherwise, the string is read from the specified location each time the record is processed and placed in the VAL field. The maximum number of characters that the string in VAL can be is 40. In addition, the appropriate device support module must be entered into the DTYP field.
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 INP Input Specification INLINK 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 stringinPOST_OnChange On Change 1 stringinPOST_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 (stringinPOST) Yes Yes Yes No APST Post Archive Monitors MENU (stringinPOST) Yes Yes Yes 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 [61] No Yes No No DESC Descriptor STRING [41] Yes Yes Yes No
The string input record has the alarm parameters common to all record types. "Alarm Fields" lists other fields related to a alarms that are common to all record types.
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 input in the simulation mode. See "Simulation Mode" for more information on simulation mode fields.
Field Summary Type DCT Default Read Write CA PP SIOL Sim Input Specifctn INLINK Yes Yes Yes No SVAL Simulation Value STRING [40] No Yes Yes Yes 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 with the value of SIML if SIML type is CONSTANT link or creates a channel access link if SIML type is PV_LINK. SVAL is likewise initialized if SIOL is CONSTANT or PV_LINK.
This routine next checks to see that device support is available and a record support read routine is defined. If either does not exist, an error message is issued and processing is terminated.
If device support includes an init_record() routine 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.
readValue is called. See "Simulation Mode" for more information on simulation mode fields and how they affect input.
If PACT has been changed to TRUE, the device support read routine has started but has not completed reading a new input value. In this case, the processing routine merely returns, leaving PACT TRUE.
recGblGetTimeStamp() is called.
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 stringin input record must have an associated set of device support routines. The primary responsibility of the device support routines is to obtain a new ASCII string value whenever read_stringin 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 VAL Current Value STRING [40] Yes Yes Yes Yes INP Input Specification INLINK 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 read_stringin(stringinRecord *prec)This routine must provide a new input value. It returns the following values:
0: Success. A new ASCII string is stored into VAL.
Other: Error.
The Soft Channel module reads a value directly into VAL.
Device support for DTYP getenv is provided for retrieving strings from environment variables. INST_IO addressing C!!@<environment variable> !!is used on the INP link field to select the desired environment variable.