EPICS Component Reference Manual
The normal use for this record type is to post a soft-event and/or process a forward link. Soft Channel device support is provided to allow the soft-event name to be read from an input link. Hardware device support for this record can provide an interrupt handler routine to trigger processing of the record when an I/O Intr event occurs.
The record-specific fields are described below, grouped by functionality.
The event record has the standard fields for specifying under what circumstances it should be processed. These fields are described 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 [40] Yes Yes Yes No PRIO Scheduling Priority MENU (menuPriority) Yes Yes Yes No PINI Process at iocInit MENU (menuPini) Yes Yes Yes No
The VAL field is a string (prior to the Base-3.15.1 release it was a short integer) providing the name of an IOC soft-event. This named soft-event gets posted whenever the record is processed.
When the soft-event name is known at design time, the VAL field should be set to the name in a loaded database file. Soft-event names do not have to be registered before use, a handle for the name is automatically created and stored when a name is first seen and the same handle returned later if the same name is re-used.
The EPVT field holds the handle for the soft-event named in the VAL field. Looking up the handle for a soft-event name is fast and uses a hash table.
For records that use the default Soft Channel device support, the soft-event name can be fetched through the INP field link, written to the VAL field and the handle looked up during record processing.
Field Summary Type DCT Default Read Write CA PP VAL Event Name To Post STRING [40] Yes Yes Yes No EPVT Event private NOACCESS No No No No
The device support routines use the address in this record to obtain input. For records that provide an interrupt handler, the INP field should specify the address of the I/O card, and the DTYP field should specify a valid device support module.
The address format differs according to the card type used. See Address Specification for information on the format of hardware addresses and specifying links.
For soft records, the INP field can be a constant, a database link, or a channel access link, and the DTYP field should be empty or set to Soft Channel.
Field Summary Type DCT Default Read Write CA PP INP Input Specification INLINK Yes Yes Yes No DTYP Device Type DEVICE 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 Event record has the alarm parameters common to all record types. Alarm Fields lists other fields related to alarms that are common to all record types.
Field Summary Type DCT Default Read Write CA PP STAT Alarm Status MENU (menuAlarmStat) No UDF Yes No No SEVR Alarm Severity MENU (menuAlarmSevr) No Yes No No AMSG Alarm Message STRING [40] No Yes No No NSTA New Alarm Status MENU (menuAlarmStat) No Yes No No NSEV New Alarm Severity MENU (menuAlarmSevr) No Yes No No NAMSG New Alarm Message STRING [40] No Yes No No ACKS Alarm Ack Severity MENU (menuAlarmSevr) No Yes No No ACKT Alarm Ack Transient MENU (menuYesNo) Yes YES Yes No No UDF Undefined UCHAR Yes 1 Yes Yes Yes
The following fields are used to operate the event record in the simulation mode. See Fields Common to Input Record Types for more information on these 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 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 SSCN Sim. Mode Scan MENU (menuScan) Yes 65535 Yes Yes No SDLY Sim. Mode Async Delay DOUBLE Yes -1.0 Yes Yes No
This routine initializes SIMM with the value of SIML if SIML type is a 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.
If device support includes init_record(), it is called.
The string in VAL is converted to a soft-event handle in EPVT.
See next section.
When the VAL field is set, the new string is converted to a soft-event handle in EPVT.
Routine process() implements the following algorithm:
readValue() is called. See Input Records for more information.
If PACT has changed to TRUE, the device support read routine has started but has not completed reading a new soft-event name. In this case, the processing routine returns immediately, leaving PACT TRUE.
Set PACT to TRUE.
Post the soft-event whose handle is in EPVT.
Check to see if monitors should be invoked. Alarm monitors are invoked if the new alarm status or severity are non-zero.
Scan forward link if set, set PACT to FALSE, and return.
Each record must have an associated set of device support routines. 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 INP Input Specification INLINK Yes Yes Yes No PRIO Scheduling Priority MENU (menuPriority) Yes Yes Yes No VAL Event Name To Post STRING [40] Yes Yes Yes No EPVT Event private NOACCESS No No No 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 only a 1-line 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(precord)This routine is optional. If provided, it is called by the record support init_record() routine.
long get_ioint_info(int cmd, struct dbCommon *precord, IOSCANPVT *ppvt)This routine is called by the dbScan 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. The get_ioint_info routine is optional, but must be provided by any device support that implements I/O Intr scanning for the event record type.
long read_event(precord)This routine returns the following values:
0: Success.
Other: Error.
A Soft Channel device support module is available. The INP link field is used to fetch the soft-event name.
The read_event() routine reads a string through INP and stores it in VAL, then looks up the named soft-event handle and sets EPVT.
See Input Records for details on soft input.