Fields Common to All Record Types

This section contains a description of the fields that are common to all record types. These fields are defined in dbCommon.dbd.

See also Fields Common to Input Record Types and Fields Common to Output Record Types.

Operator Display Parameters

The NAME field contains the record name which must be unique within an EPICS Channel Access name space. The name is supplied by the application developer and is the means of identifying a specific record. The name has a maximum length of 60 characters and should use only this limited set of characters:

 a-z A-Z 0-9 _ - : [ ] < > ;

The DESC field may be set to provide a meaningful description of the record's purpose. Maximum length is 40 characters.

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

Scan Fields

These fields contain information related to how and when a record processes. A few records have unique fields that also affect how they process. These fields, if any, will be listed and explained in the section for each record.

The SCAN field specifies the scanning period for periodic record scans or the scan type for non-periodic record scans. The default set of values for SCAN can be found in menuScan.dbd.

The choices provided by this menu are:

Additional periodic scan rates may be defined for individual IOCs by making a local copy of menuScan.dbd and adding more choices as required. Scan rates should normally be defined in order, with the fastest rates appearing first. Scan periods may now be specified in seconds, minutes, hours or Hertz/Hz, and plural time units will also be accepted (seconds are used if no unit is mentioned in the choice string). For example the rates given below are all valid:

 1 hour
 0.5 hours
 15 minutes
 3 seconds
 1 second
 2 Hertz

The PINI field specifies record processing at initialization. If it is set to YES during database configuration, the record is processed once at IOC initialization (before the normal scan tasks are started).

The PHAS field orders the records within a specific SCAN group. This is not meaningful for passive records. All records of a specified phase are processed before those with higher phase number. Whenever possible it is better to use linked passive records to enforce the order of processing rather than a phase number.

The EVNT field specifies an event number. This event number is used if the SCAN field is set to Event. All records with scan type Event and the same EVNT value will be processed when a call to post_event for EVNT is made. The call to post_event is: post_event(short event_number).

The PRIO field specifies the scheduling priority for processing records with SCAN=I/O Event and asynchronous record completion tasks.

The DISV field specifies a "disable value". Record processing is immediately terminated if the value of this field is equal to the value of the DISA field, i.e. the record is disabled. Note that field values of a record can be changed by database put or Channel Access, even if a record is disabled.

The DISA field contains the value that is compared with DISV to determine if the record is disabled. The value of the DISA field is obtained via SDIS if SDIS is a database or channel access link. If SDIS is not a database or channel access link, then DISA can be set via dbPutField or dbPutLink.

If the PROC field of a record is written to, the record is processed.

The DISS field defines the record's "disable severity". If this field is not NO_ALARM and the record is disabled, the record will be put into alarm with this severity and a status of DISABLE_ALARM.

The LSET field contains the lock set to which this record belongs. All records linked in any way via input, output, or forward database links belong to the same lock set. Lock sets are determined at IOC initialization time, and are updated whenever a database link is added, removed or altered.

The LCNT field counts the number of times dbProcess finds the record active during successive scans, i.e. PACT is TRUE. If dbProcess finds the record active MAX_LOCK times (currently set to 10) it raises a SCAN_ALARM.

The PACT field is TRUE while the record is being processed. For asynchronous records PACT can be TRUE from the time record processing is started until the asynchronous completion occurs. As long as PACT is TRUE, dbProcess will not call the record processing routine. See Application Developers Guide for details on usage of PACT.

The FLNK field is a database link to another record (the "target" record). Processing a record with a specified FLNK field will force processing of the target record, provided the target record's SCAN field is set to Passive.

The SPVT field is for internal use by the scanning system.

FieldSummaryTypeDCT DefaultReadWriteCA PP
SCANScan MechanismMENU (menuScan)Yes YesYesNo
PINIProcess at iocInitMENU (menuPini)Yes YesYesNo
PHASScan PhaseSHORTYes YesYesNo
EVNTEvent NameSTRING [40]Yes YesYesNo
PRIOScheduling PriorityMENU (menuPriority)Yes YesYesNo
DISVDisable ValueSHORTYes1YesYesNo
SDISScanning DisableINLINKYes YesYesNo
PROCForce ProcessingUCHARNo YesYesYes
DISSDisable Alarm SevrtyMENU (menuAlarmSevr)Yes YesYesNo
PACTRecord activeUCHARNo YesNoNo
FLNKForward Process LinkFWDLINKYes YesYesNo

Alarm Fields

These fields indicate the status and severity of alarms, or else determine the how and when alarms are triggered. Of course, many records have alarm-related fields not common to all records. These fields are listed and explained in the appropriate section on each record.

The STAT field contains the current alarm status.

The SEVR field contains the current alarm severity.

These two fields are seen outside database access. The NSTA and NSEV fields are used by the database access, record support, and device support routines to set new alarm status and severity values. Whenever any software component discovers an alarm condition, it uses the following macro function: recGblSetSevr(precord,new_status,new_severity) This ensures that the current alarm severity is set equal to the highest outstanding alarm. The file alarm.h defines all allowed alarm status and severity values.

The ACKS field contains the highest unacknowledged alarm severity.

The ACKT field specifies if it is necessary to acknowledge transient alarms.

The UDF indicates if the record's value is UnDeFined. Typically this is caused by a failure in device support, the fact that the record has never been processed, or that the VAL field currently contains a NaN (not a number). UDF is initialized to TRUE at IOC initialization. Record and device support routines which write to the VAL field are responsible for setting UDF.

FieldSummaryTypeDCT DefaultReadWriteCA PP
STATAlarm StatusMENU (menuAlarmStat)NoUDFYesNoNo
SEVRAlarm SeverityMENU (menuAlarmSevr)No YesNoNo
NSTANew Alarm StatusMENU (menuAlarmStat)No YesNoNo
NSEVNew Alarm SeverityMENU (menuAlarmSevr)No YesNoNo
ACKSAlarm Ack SeverityMENU (menuAlarmSevr)No YesNoNo
ACKTAlarm Ack TransientMENU (menuYesNo)YesYESYesNoNo

Device Fields

The RSET field contains the address of the Record Support Entry Table. See the Application Developers Guide for details on usage.

The DSET field contains the address of Device Support Entry Table. The value of this field is determined at IOC initialization time. Record support routines use this field to locate their device support routines.

The DPVT field is is for private use of the device support modules.

FieldSummaryTypeDCT DefaultReadWriteCA PP

Debugging Fields

The TPRO field is used for trace processing. If this field is non-zero a message is printed whenever this record is processed, and when any other record in the same lock-set is processed by a database link from this record.

The BKPT field indicates if there is a breakpoint set at this record. This supports setting a debug breakpoint in the record processing. STEP through database processing can be supported using this.

FieldSummaryTypeDCT DefaultReadWriteCA PP
TPROTrace ProcessingUCHARNo YesYesNo

Miscellaneous Fields

The ASG field contains a character string value defining the access security group for this record. If left empty, the record is placed in group DEFAULT.

The ASP field is a field for private use of the access security system.

The DISP field controls dbPutFields to this record which are normally issued by channel access. If the field is set to TRUE all dbPutFields directed to this record are ignored except to the field DISP itself.

The DTYP field specifies the device type for the record. Each record type has its own set of device support routines which are specified in devSup.ASCII. If a record type does not have any associated device support, DTYP and DSET are meaningless.

The MLOK field contains the monitor lock. The lock used by the monitor routines when the monitor list is being used. The list is locked whenever monitors are being scheduled, invoked, or when monitors are being added to or removed from the list. This field is accessed only by the dbEvent routines.

The MLIS field is the head of the list of monitors connected to this record. Each record support module is responsible for triggering monitors for any fields that change as a result of record processing. Monitors are present if mlis count is greater than zero. The call to trigger monitors is: db_post_event(precord,&data,mask), where "mask" is some combination of DBE_ALARM, DBE_VALUE, and DBE_LOG.

The PPN field contains the address of a putNotify callback.

The PPNR field contains the next record for PutNotify.

The PUTF field is set to TRUE if dbPutField caused the current record processing.

The RDES field contains the address of dbRecordType

The RPRO field specifies a reprocessing of the record when current processing completes.

The TIME field contains the time when this record was last processed in standard format.

The TSE field indicates the mechanism to use to get the time stamp. '0' - call get time as before '-1' - call the time stamp driver and use the best source available. '-2' - the device support provides the time stamp from the hardware. Values between 1-255 request the time of the last occurance of a generalTime event.

The TSEL field contains an input link for obtaining the time stamp. If this link references the .TIME field of a record then the time stamp of the referenced record becomes the time stamp for this record as well. In this case, an internal flag is set and ".TIME" is then overwritten by ".VAL". If any other field is referenced, the field value is read and stored in the .TSE field which is then used to acquire a timestamp.

FieldSummaryTypeDCT DefaultReadWriteCA PP
ASGAccess Security GroupSTRING [29]Yes YesYesNo
ASPAccess Security PvtNOACCESSNo NoNoNo
DISPDisable putFieldUCHARNo YesYesNo
DTYPDevice TypeDEVICEYes YesYesNo
PPNpprocessNotifyNOACCESSNo NoNoNo
PPNRpprocessNotifyRecordNOACCESSNo NoNoNo
PUTFdbPutField processUCHARNo YesNoNo
RDESAddress of dbRecordTypeNOACCESSNo NoNoNo
RPROReprocess UCHARNo YesNoNo
TSETime Stamp EventSHORTYes YesYesNo
TSELTime Stamp LinkINLINKYes YesYesNo