Data Fanout Record (dfanout)

The Data Fanout or “dfanout” record is used to forward data to up to eight other records. It’s similar to the fanout record except that the capability to forward data has been added to it. If has no associated device support.

Parameter Fields

The record-specific fields are described below, grouped by functionality.

Scan Parameters

The data fanout record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in Scan Fields.

Desired Output Parameters

The data fanout record must specify where the desired output value originates, i.e., the data which is to be fowarded 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

Write Parameters

The OUTA-OUTH 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.

Menu dfanoutSELM

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
OUTB	Output Spec B	OUTLINK	Yes		Yes	Yes	No
OUTC	Output Spec C	OUTLINK	Yes		Yes	Yes	No
OUTD	Output Spec D	OUTLINK	Yes		Yes	Yes	No
OUTE	Output Spec E	OUTLINK	Yes		Yes	Yes	No
OUTF	Output Spec F	OUTLINK	Yes		Yes	Yes	No
OUTG	Output Spec G	OUTLINK	Yes		Yes	Yes	No
OUTH	Output Spec H	OUTLINK	Yes		Yes	Yes	No

Operator Display Parameters

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

Alarm Parameters

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 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

Monitor Parameters

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, everytime the value changes, a monitor will be triggered; if they have a value of -1, everytime 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

Run-Time Parameters and Simulation Mode Parameters

These parameters are used by the run-time code for processing the data fanout record. Ther 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

Record Support

Record Support Routines

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.

Record Processing

The process() routine first checks that DOL is not a constant link and that OMSL is set to “closed_loop”. If so, it retrieves a value through DOL and places it into VAL. 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.

VAL is then sent through the OUTA-OUTH links by calling dbPutLink() for each link, conditional on the setting of SELM and the value in SELN.

Value and archive monitors are posted on the VAL field if appropriate based on the settings of MDEL and ADEL respectively.

The data fanout’s forward link FLNK is processed.

PACT is set FALSE, and the process() routine returns.