View source for RRM 3-13 Long Output

[[RRM 3-13|EPICS Record Reference Manual]]


= longout - Long Output =

The normal use for the long output or "longout" record type is to store long integer values of up to 32 bits  and write them to hardware devices. The <CODE>Soft Channel</CODE> device support routine can also be used to write values to other records via database or channel access links. The OUT field determines how the record is used. The record supports alarm limits and graphics and control limits.

== Parameter Fields ==

The fields in this record fall into the following categories:

* scan parameters
* desired output parameters
* write parameters
* operator display parameters
* alarm parameters
* monitor parameters
* simulation mode parameters

=== Scan Parameters ===

The longout record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in [[RRM 3-13 dbCommon#Scan Fields|Scan Fields]]. In addition, [[RRM 3-13 Concepts#Scanning Specification|Scanning Specification]] explains how these fields are used. Note that I/O event scanning is only supported for those card types that interrupt.


=== Desired Output Parameters ===

The data fanout record must specify where the desired output originates, i.e., the 32 bit integer value it is to write. The output mode select (OMSL) field determines whether the output originates from another record or from database access. When set to <CODE>closed_loop</CODE>, the desired output is retrieved from the link specified in the desired output (DOL) field--which can specify either a database or channel access link--and placed into the VAL field. When set to <CODE>supervisory</CODE>, the desired output can be written into the VAL field via dpPuts at run-time.

The DOL field can be configured as constant, so that when the record is initialized, the VAL field will be initialized with this VALUE. If DOL is a constant, then the OMSL loop cannot be <CODE>closed_loop</CODE>. 


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TR>
<TD>DOL<TD>Desired Output Location (input link)<TD>INLINK<TD>Yes<TD>0<TD>No<TD>No<TD>N/A<TR>
<TD>OMSL<TD>Output Mode Select<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TR>
<TD>VAL<TD>Value Field<TD>LONG<TD>No<TD>0<TD>Yes<TD>Yes<TD>Yes
</TABLE>


=== Write Parameters ===

The OUT link field determines where the record is to send its output. For records that write values to hardware devices, the OUT output link field must specify the address of the I/O card, and the DTYP field must specify the name of the corresponding device support module. You can see a list of the device support modules currently supported at the user's local site by using the <CODE>dbst</CODE> utility in R3.13.

For soft records, the OUT output link can be a constant, a database link, or a channel access link. If the link is a constant, the result is no output. The DTYP field must then specify the <CODE>Soft Channel</CODE> device support routine.

See [[RRM 3-13 Concepts#Address Specification|Address Specification]] for information on the format of hardware addresses and database links.


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TR>
<TD>OUT<TD>Output Link<TD>OUTLINK<TD>Yes<TD>0<TD>No<TD>No<TD>N/A<TR>
<TD>DTYP<TD>Device Type<TD>DEVCHOICE<TD>Yes<TD>0<TD>Yes<TD>No<TD>No
</TABLE>


=== Operator Display Parameters ===

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

EGU is a string of up to 16 characters describing the units that the long output measures. It is retrieved by the <CODE>get_units</CODE> record support routine.

The HOPR and LOPR fields set the upper and lower display limits for the VAL, HIHI, HIGH, LOW, and LOLO fields. Both the <CODE>get_graphic_double</CODE> and <CODE>get_control_double</CODE> record support routines retrieve these fields.

See [[RRM 3-13 dbCommon#Fields Common to All Record Types|Fields Common to All Record Types]] for more on the record name (NAME) and description (DESC) fields.


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TH>PP<TR>
<TD>EGU<TD>Engineering Units<TD>STRING [16]<TD>Yes<TD>null<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>HOPR<TD>High Operating Range<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>LOPR<TD>Low Operating Range<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>NAME<TD>Record Name<TD>STRING [29]<TD>Yes<TD>0<TD>Yes<TD>No<TD>No<TD>&nbsp;<TR>
<TD>DESC<TD>Description<TD>STRING [29]<TD>Yes<TD>Null<TD>Yes<TD>Yes<TD>No<TD>No
</TABLE>


=== Alarm Parameters ===

The possible alarm conditions for long inputs are the SCAN, READ, INVALID, and limit alarms. The SCAN and READ alarms are not configurable by the user because their severity is always MAJOR. The INVALID alarm is called by the record support routine when the record or device support routines cannot write the record's output. The IVOA field specifies the action to take in this case.

The limit alarms are configured by the user in the HIHI, LOLO, HIGH, and LOW fields using floating-point values. For each of these fields, there is a corresponding severity field which can be either NO_ALARM, MINOR, or MAJOR. The HYST field contains the alarm deadband around each limit alarm.

See the See [[RRM 3-13 Concepts#Alarm Specification|Alarm Specification]] for a complete explanation of alarms and these fields. For an explanation of the IVOA and IVOV fields, see [[RRM 3-13 Common#Output Records|Output Records]]. [[RRM 3-13 dbCommon#Alarm Fields|Alarm Fields]] lists other fields related to a alarms that are common to all record types. 


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TH>PP<TR>
<TD>HIHI<TD>Hihi Alarm Limit<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>HIGH<TD>High Alarm Limit<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>LOW<TD>Low Alarm Limit<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>LOLO<TD>Lolo Alarm Limit<TD>FLOAT<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>HHSV<TD>Hihi Alarm Severity<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>HSV<TD>High Alarm Severity<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>LSV<TD>Low Alarm Severity<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>LLSV<TD>Lolo Alarm Severity<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>Yes<TR>
<TD>HYST<TD>Alarm Deadband<TD>DOUBLE<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>IVOA<TD>Invalid Alarm Output Action<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>IVOV<TD>Invalid Alarm Output Value, in eng. units<TD>DOUBLE<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No
</TABLE>


=== Monitor Parameters ===

These parameters are used to determine when to send monitors placed on the value field. The monitors are sent when the value field exceeds the last monitored field by the appropriate delta. If these fields have a value of zero, everytime the value changes, a monitor will be triggered; if they have a value of -1, everytime the record is scanned, monitors are triggered. The ADEL field is the delta for archive monitors, and the MDEL field is the delta for all other types of monitors. See [[RRM 3-13 Concepts#Monitor Specification|Monitor Specification]] for a complete explanation of monitors.


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TH>PP<TR>
<TD>ADEL<TD>Archive Deadband<TD>DOUBLE<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>MDEL<TD>Monitor, i.e. value change, Deadband<TD>DOUBLE<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No
</TABLE>


=== Run-time and Simulation Mode Parameters ===

The LALM, MLST, and ALST fields are used to implement the hysteresis factors for monitor callbacks. Only if the difference between these fields and the corresponding value field is greater than the appropriate delta (MDEL, ADEL, HYST)--only then are monitors triggered. For instance, only if the difference between VAL and MLST is greater than MDEL are the monitors triggered for VAL.


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TH>PP<TR>
<TD>LALM<TD>Last Alarm Monitor Trigger Value<TD>DOUBLE<TD>No<TD>0<TD>Yes<TD>No<TD>No<TD>No<TR>
<TD>ALST<TD>Last Archiver Monitor Trigger Value<TD>DOUBLE<TD>No<TD>0<TD>Yes<TD>No<TD>No<TD>No<TR>
<TD>MLST<TD>Last Value Change Monitor Trigger Value<TD>DOUBLE<TD>No<TD>0<TD>Yes<TD>No<TD>No<TD>No
</TABLE>

The following fields are used to operate the long output in the simulation mode. See [[RRM 3-13 Common#Fields Common to Many Record Types|Fields Common to Many Record Types]] for more information on the simulation mode fields


<TABLE BORDER="1">
<TH>Field<TH>Summary<TH>Type<TH>DCT<TH>Initial<TH>Access<TH>Modify<TH>Rec Proc Monitor<TH>PP<TR>
<TD>SIOL<TD>Simulation Value Location<TD>INLINK<TD>Yes<TD>0<TD>No<TD>No<TD>N/A<TD>No<TR>
<TD>SVAL<TD>Simulation Value<TD>DOUBLE<TD>No<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>SIML<TD>Simulation Mode Location<TD>INLINK<TD>Yes<TD>0<TD>No<TD>No<TD>N/A<TD>No<TR>
<TD>SIMM<TD>Simulation Mode<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>No<TD>0<TD>Yes<TD>Yes<TD>No<TD>No<TR>
<TD>SIMS<TD>Simulation Mode Alarm Severity<TD>[[RRM 3-13 Menu Choices|GBLCHOICE]]<TD>Yes<TD>0<TD>Yes<TD>Yes<TD>No<TD>No
</TABLE>


== Record Support ==

=== Record Support Routines ===

==== init_record ====

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 VAL is initialized to its value 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.

==== process ====

See next section.

==== get_value ====

Fills in the values of struct valueDes so that they refer to VAL.

==== get_units ====

Retrieves EGU.

==== get_graphic_double ====

Sets the upper display and lower display limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.

==== get_control_double ====

Sets the upper control and the lower control limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.

==== get_alarm_double ====

Sets the following values:

  upper_alarm_limit = HIHI
  upper_warning_limit = HIGH
  lower_warning_limit = LOW
  lower_alarm_limit = LOLO


=== 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 [[RRM 3-13 Common#Output Records|Output Records]] for more information. If the return status of recGblGetLinkValue is zero then UDF is set to FALSE.
# Check alarms. This routine checks to see if the new VAL causes the alarm status and severity to change. If so, NSEV, NSTA and LALM are set. It also honors the alarm hysteresis factor (HYST). Thus the value must change by more than HYST before the alarm status and severity is lowered.
# Check severity and write the new value. See [[RRM 3-13 Common#Invalid Alarm Output Action|Invalid Alarm Output Action]] for information on how INVALID alarms affect output records.
# 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 ADEL and MDEL conditions are met.
#* NSEV and NSTA are reset to 0.
# Scan forward link if necessary, set PACT FALSE, and return.


== Device Support ==

=== Fields Of Interest To Device Support ===

Each long output record must have an associated set of device support routines. The primary responsibility of the device support routines is to output a new value whenever write_longout is called. The device support routines are primarily interested in the following fields:

<TABLE BORDER="1">
<TH>Name<TH>Summary<TH>Description<TR>
<TD>PACT<TD>Processing Active<TD rowspan=4>See [[RRM 3-13 dbCommon#Fields Common to All Record Types|Fields Common to All Record Types]] for an explanation of these fields.<TR>
<TD>DPVT<TD>Device Private<TR>
<TD>NSEV<TD>New Alarm Severity<TR>
<TD>NSTA<TD>New Alarm Status<TR>
<TD>OUT<TD>Output Link<TD>This field is used by the device support routines to locate its output.
</TABLE>


=== Device Support Routines ===

Device support consists of the following routines:

==== init ====

 init()

This routine is called once during IOC initialization.

==== init_record ====

 init_record(precord)

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

==== get_ioint_info ====

 get_ioint_info(int cmd,struct 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.

==== write_longout ====

 write_longout(precord)

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

* 0: Success.
* Other: Error.


=== Device Support For Soft Records ===

The <CODE>Soft Channel</CODE> module writes the current value of VAL.

If the OUT link type is PV_LINK, then dbCaAddInlink is called by init_record.

write_longout calls recGblPutLinkValue to write the current value of VAL.

See [[RRM 3-13 Common#Soft Output|Soft Output]] for a further explanation.


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EPICS Record Reference Manual - 19 MAY 1998