RRM 3-14 Data Fanout
dfanout - Data Fanout
- Johnny Tang, Matthew Bickley, and Chip Watson
- Continuous Electron Beam Accelerator Facility
- Southeastern Universities Research Association
The dfanout record or data fanout 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. It has no associated device support.
Parameter Fields
The fields in this record can be classified into the following categories:
- scan parameters
- desired output parameters
- write parameters
- operator display parameters
- alarm parameters
- monitor parameters
- run-time and simulation mode parameters
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. In addition, Scanning Specification explains how these fields are used. Since the data fanout record supports no direct interfaces to hardware, it cannot be scanned on I/O interrupt, so its SCAN field cannot be I/O Intr.
Desired Output Parameters
The data fanout record must specify where the desired output value originates, i.e., the data which it is to forward 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 (DOL) field, which can specify either a database or channel access link, and placed into the VAL field. When set to supervisory, the desired output can be written to the VAL field via dpPuts 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 | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| DOL | Desired Output Location (Input Link) | INLINK | Yes | 0 | No | No | N/A | No |
| OMSL | Output Mode Select | GBLCHOICE | Yes | 0 | Yes | Yes | No | No |
| VAL | Value Field | DOUBLE | No | 0 | Yes | Yes | No | 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 link(s) are to be used. SELM is a menu, with the following choices: "All", "Specified", "Mask". If SELM=="All", then all output links are used, and the values of SELL and SELN are ignored.
If SELM=="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 its value retrieved from another EPICS PV. If SELL is a valid PV link, then SELN will be set to the value of the linked PV
If SELM=="Mask", then SELN will be treated as a bit mask. If bit one of SELN is set, then OUTA will be used, if bit two is set, OUTB will be used. Thus if SELN==5, OUTC and OUTA will be used.
| Field | Summary | Type | DCT | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| OUTA | Output Link A | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTB | Output Link B | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTC | Output Link C | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTD | Output Link D | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTE | Output Link E | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTF | Output Link F | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTG | Output Link G | OUTLINK | Yes | 0 | No | No | N/A | No |
| OUTH | Output Link H | OUTLINK | Yes | 0 | No | No | N/A | No |
Operator Display Parameters
These parameters are used to present meaningful data to the operator. They display the value and other parameters of the data fanout record either textually or graphically.
The EGU field can contain a string of up to 16 characters describing the value in the VAL field.
The HOPR and LOPR fields determine the upper and lower display limits for graphics displays and the upper and lower control limits for control displays. They apply to the VAL, HIHI, HIGH, LOW, and LOLO fields. The record support routines get_graphic_double or get_control_double retrieve HOPR and LOPR
See Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.
| Field | Summary | Type | DCT | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| EGU | Engineering Units | STRING [16] | Yes | null | Yes | Yes | No | No |
| HOPR | High Operating Range | FLOAT | Yes | 0 | Yes | Yes | No | No |
| LOPR | Low Operating Range | FLOAT | Yes | 0 | Yes | Yes | No | No |
| NAME | Record Name | STRING [29] | Yes | 0 | Yes | No | No | |
| DESC | Description | STRING [29] | Yes | Null | Yes | Yes | No | 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 alarms and these fields. Alarm Fields lists other fields related to a alarms that are common to all record types.
| Field | Summary | Type | DCT | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| HIHI | Hihi Alarm Limit | FLOAT | Yes | 0 | Yes | Yes | No | Yes |
| HIGH | High Alarm Limit | FLOAT | Yes | 0 | Yes | Yes | No | Yes |
| LOW | Low Alarm Limit | FLOAT | Yes | 0 | Yes | Yes | No | Yes |
| LOLO | Lolo Alarm Limit | FLOAT | Yes | 0 | Yes | Yes | No | Yes |
| HHSV | Hihi Alarm Severity | GBLCHOICE | Yes | 0 | Yes | Yes | No | Yes |
| HSV | High Alarm Severity | GBLCHOICE | Yes | 0 | Yes | Yes | No | Yes |
| LSV | Low Alarm Severity | GBLCHOICE | Yes | 0 | Yes | Yes | No | Yes |
| LLSV | Lolo Alarm Severity | GBLCHOICE | Yes | 0 | Yes | Yes | No | Yes |
| HYST | Alarm Deadband | DOUBLE | Yes | 0 | Yes | Yes | No | No |
Monitor Parameters
These parameters are used to determine when to send monitors placed on the VAL field. The monitors are sent when the value field exceeds the last monitored field by the specified deadband, ADEL for archiver 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 | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| ADEL | Archive Deadband | DOUBLE | Yes | 0 | Yes | Yes | No | No |
| MDEL | Monitor, i.e. value change, Deadband | DOUBLE | Yes | 0 | Yes | Yes | No | No |
Run-Time Parameters and Simulation Mode Parameters
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 | Initial | Access | Modify | Rec Proc Monitor | PP |
|---|---|---|---|---|---|---|---|---|
| LALM | Last Alarm Monitor Trigger Value | DOUBLE | No | 0 | Yes | No | No | No |
| ALST | Last Archiver Monitor Trigger Value | DOUBLE | No | 0 | Yes | No | No | No |
| MLST | Last Value Change Monitor Trigger Value | DOUBLE | No | 0 | Yes | No | No | No |
Record Support
Record Support Routines
init_record()
This routine initializes all output links that are defined. Then it initializes DOL is DOL is a constant or 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_value()
This routine fills in the members of struct valueDes with the VAL fields value and characteristics.
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 HOPR and the lower_disp_limit member to LOPR. If the referenced field is not one of the above fields, then the 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 if the referenced field is VAL:
upper_alarm_limit = HIHI upper_warning_limit = HIGHT 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 retrieves a value for DOL and places it in VAL if OMSL is set to closed loop mode. If ann error occurs, then UDF is set to FALSE. - PACT is set TRUE.
- VAL is then sent to all the records specified in the OUTA-OUTH fields by calling the
recGblPutLinkValue()for each link. - Alarms are checked and monitors are called if conditions apply.
- The data fanout's own forward link is then processed.
- PACT is set FALSE, and the
process()routine returns. A -1 is returned if there was an error writing values to one of the output links.
EPICS Record Reference Manual - 19 MAY 1998
