EPICS Component Reference Manual
The Data Fanout or "dfanout" record is used to forward data to up to 16 other records. It's similar to the fanout record except that the capability to forward data has been added to it. It has no associated device support.
Since 7.0.10 the number of output links has been increased from 8 to 16 and IVOA and IVOV fields have been added.
The record-specific fields are described below, grouped by functionality.
The data fanout record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in Scan Fields.
The data fanout record must specify where the desired output value originates, i.e., the data which is to be forwarded to the records in its output links. The output mode select (OMSL) field determines whether the output originates from another record or from run-time database access. When set to closed_loop, the desired output is retrieved from the link specified in the Desired Output Link (DOL) field, which can specify either a database or a channel access link, and placed into the VAL field. When set to supervisory, the desired output can be written to the VAL field via dbPuts at run-time.
The DOL field can also be a constant in which case the VAL field is initialized to the constant value.
Note that there are no conversion parameters, so the desired output value undergoes no conversions before it is sent out to the output links.
Field Summary Type DCT Default Read Write CA PP DOL Desired Output Link INLINK Yes Yes Yes No OMSL Output Mode Select MENU (menuOmsl) Yes Yes Yes No VAL Desired Output DOUBLE Yes Yes Yes Yes
The OUTA-OUTP fields specify where VAL is to be sent. Each field that is to forward data must specify an address to another record. See Address Specification for information on specifying links.
The SELL, SELM, and SELN fields specify which output links are to be used.
SELM is a menu, with three choices:
Index Identifier Choice String 0 dfanoutSELM_All All 1 dfanoutSELM_Specified Specified 2 dfanoutSELM_Mask Mask
If SELM is All, then all output links are used, and the values of SELL and SELN are ignored.
If SELM is Specified, then the value of SELN is used to specify a single link which will be used. If SELN==0, then no link will be used; if SELN==1, then OUTA will be used, and so on.
SELN can either have its value set directly, or have it retrieved from another EPICS PV. If SELL is a valid PV link, then SELN will be read from the linked PV.
If SELM is Mask, then SELN will be treated as a bit mask. If bit zero (the LSB) of SELN is set, then OUTA will be written to; if bit one is set, OUTB will be written to, and so on. Thus when SELN==5, both OUTC and OUTA will be written to.
Field Summary Type DCT Default Read Write CA PP SELL Link Selection Loc INLINK Yes Yes Yes No SELM Select Mechanism MENU (dfanoutSELM) Yes Yes Yes No SELN Link Selection USHORT No 1 Yes Yes No OUTA Output Spec A OUTLINK Yes Yes Yes No ⋮ OUTP Output Spec P OUTLINK Yes Yes Yes No
These parameters are used to present meaningful data to the operator. They do not affect the functioning of the record at all.
NAME is the record's name, and can be useful when the PV name that a client knows is an alias for the record.
DESC is a string that is usually used to briefly describe the record.
EGU is a string of up to 16 characters naming the engineering units that the VAL field represents.
The HOPR and LOPR fields set the upper and lower display limits for the VAL, HIHI, HIGH, LOW, and LOLO fields.
The PREC field determines the floating point precision (i.e. the number of digits to show after the decimal point) with which to display VAL and the other DOUBLE fields.
See Fields Common to All Record Types for more about 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 EGU Engineering Units STRING [16] Yes Yes Yes No HOPR High Operating Range DOUBLE Yes Yes Yes No LOPR Low Operating Range DOUBLE Yes Yes Yes No PREC Display Precision SHORT Yes Yes Yes No
The possible alarm conditions for data fanouts are the SCAN, READ, INVALID, and limit alarms. The SCAN and READ alarms are called by the record routines. The IVOA field specifies the action to take in this case.
For an explanation of the IVOA and IVOV fields, see Invalid Output Action Fields.
The limit alarms are configured by the user in the HIHI, LOLO, HIGH, and LOW fields using floating point values. The limit alarms apply only to the VAL field. The severity for each of these limits is specified in the corresponding field (HHSV, LLSV, HSV, LSV) and can be either NO_ALARM, MINOR, or MAJOR. In the hysteresis field (HYST) can be entered a number which serves as the deadband on the limit alarms.
See Alarm Specification for a complete explanation of record alarms and of the standard fields. Alarm Fields lists other fields related to alarms that are common to all record types.
Field Summary Type DCT Default Read Write CA PP HIHI Hihi Alarm Limit DOUBLE Yes Yes Yes Yes HIGH High Alarm Limit DOUBLE Yes Yes Yes Yes LOW Low Alarm Limit DOUBLE Yes Yes Yes Yes LOLO Lolo Alarm Limit DOUBLE Yes Yes Yes Yes HHSV Hihi Severity MENU (menuAlarmSevr) Yes Yes Yes Yes HSV High Severity MENU (menuAlarmSevr) Yes Yes Yes Yes LSV Low Severity MENU (menuAlarmSevr) Yes Yes Yes Yes LLSV Lolo Severity MENU (menuAlarmSevr) Yes Yes Yes Yes HYST Alarm Deadband DOUBLE Yes Yes Yes No IVOA INVALID output action MENU (menuIvoa) Yes Yes Yes No IVOV INVALID output value DOUBLE Yes Yes Yes No
These parameters are used to determine when to send monitors placed on the VAL field. These monitors are sent when the value field exceeds the last monitored fields by the specified deadband, ADEL for archivers monitors and MDEL for all other types of monitors. If these fields have a value of zero, every time the value changes, a monitor will be triggered; if they have a value of -1, every time the record is scanned, monitors are triggered. See "Monitor Specification" for a complete explanation of monitors.
Field Summary Type DCT Default Read Write CA PP ADEL Archive Deadband DOUBLE Yes Yes Yes No MDEL Monitor Deadband DOUBLE Yes Yes Yes No
These parameters are used by the run-time code for processing the data fanout record. They are not configurable. They are used to implement the hysteresis factors for monitor callbacks.
Field Summary Type DCT Default Read Write CA PP LALM Last Value Alarmed DOUBLE No Yes No No ALST Last Value Archived DOUBLE No Yes No No MLST Last Val Monitored DOUBLE No Yes No No
init_record() §This routine initializes all output links that are defined. Then it initializes DOL if DOL is a constant or a PV_LINK. When initializing the output links and the DOL link, a non-zero value is returned if an error occurs.
process() §See next section.
get_units() §The routine copies the string specified in the EGU field to the location specified by a pointer which is passed to the routine.
get_graphic_double() §If the referenced field is VAL, HIHI, HIGH, LOW, or LOLO, this routine sets the upper_disp_limit member of the dbr_grDouble structure to the HOPR and the lower_disp_limit member to the LOPR. If the referenced field is not one of the above fields, then recGblGetControlDouble() routine is called.
get_control_double() §Same as the get_graphic_double() routine except that it uses the dbr_ctrlDouble structure.
get_alarm_double() §This sets the members of the dbr_alDouble structure to the specified alarm limits when the referenced field is VAL:
upper_alarm_limit = HIHI
upper_warning_limit = HIGH
lower_warning_limit = LOW
lower_alarm_limit = LOLO
If the referenced field is not VAL, the recGblGetAlarmDouble() routine is called.
If OMSL is "closed_loop" and DOL is not a constant link read the new value of VAL from DOL. If no errors occur, UDF is set to FALSE.
PACT is set TRUE and the record's timestamp is set.
A value is fetched from SELL and placed into SELN.
Alarms ranges are checked against the contents of the VAL field.
Check severity and then send the value through the OUTA-OUTP links, depending on the setting of SELM and the value in SELN.
See Invalid Output Action Fields for information on how INVALID alarms affect output records.
Value and archive monitors are posted on the VAL field if appropriate based on the settings of MDEL and ADEL respectively.
Scan forward link if necessary, set PACT FALSE, and return.