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EPICS Record Reference Manual
Chapter 17: longin--Long Input
1. Introduction
The normal use for the long input record or "longin" record is to
retrieve a long integer value of up to 32 bits. Device support routines
are provided to support direct interfaces to hardware. In addition, the Soft
Channel
device module is provided to obtain input via database
or channel access links or via dbPutField or dbPutLink requests.
The fields in this record fall into the following categories:
scan parameters
read parameters
operator display parameters
alarm parameters
run-time and simulation mode parameters
2. Scan Parameters
The long input record has the standard fields for specifying under what
circumstances the record will be processed. These fields are listed in Scan
Fields, Chapter 2, 2. In addition, Scanning
Specification, Chapter 1, 1, explains how these fields are
used. Note that I/O event scanning is only supported for those card
types that interrupt.
3. Read Parameters
The device support routines use the INP field to obtain the record's
input. For records that obtain their input from devices, the INP field
must contain the address of the I/O card, and the DTYP field must
specify the proper device support module. Be aware that the address
format differs according to the I/O bus used. You can see a list of the
device support modules currently supported at the user's local site by
using the dbst
utility in R3.13.
For soft records, the INP can be a constant, a database link, or a
channel access link. The value is read directly into VAL. The Soft
Channel
device support module is available for longin records.
See Address
Specification, Chapter 1, 2, for information on the format of
hardware addresses and a database links.
Field | Summary | Type | DCT | Initial | Access | Modify | Rec
Proc Monitor | PP |
---|
VAL | Value Field | LONG | No | 0 | Yes | Yes | Yes | Yes |
INP | Input Link | INLINK | Yes | 0 | No | No | N/A | No |
DTYP | Device Type | DEVCHOICE | Yes | 0 | Yes | No | No | |
4. Operator Display Parameters
These parameters are used to present meaningful data to the operator.
These fields are used to display the value and other parameters of the
long input either textually or graphically.
EGU is a string of up to 16 characters describing the units that the
long input measures. It is retrieved by the get_units
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 get_graphic_double
and get_control_double
record support routines retrieve
these fields.
See Chapter
2, 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 | No |
DESC | Description | STRING [29] | Yes | Null | Yes | Yes | No | No |
5. Alarm Parameters
The possible alarm conditions for long inputs are the SCAN, READ, and
limit alarms. The SCAN and READ alarms are called by the record or
device support routines.
The limit alarms are configured by the user in the HIHI, LOLO, HIGH, and
LOW fields using numerical values. For each of these fields, there is a
corresponding severity field which can be either NO_ALARM, MINOR, or
MAJOR. The HYST field can be used to specify a deadband around each
limit. See Alarm
Specification, Chapter 1, 4, for a complete explanation of
alarms and these fields. Alarm
Fields, Chapter 2, 3, 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 |
6. 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 (see the next section) by the appropriate deadband.
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 used by
archive monitors and the MDEL field for all other types of monitors. See
Monitor
Specification, Chapter 1, 5, 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 |
7. 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.
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 |
The following fields are used to operate the long input in the
simulation mode. See Chapter
3, Fields Common to Many Record Types, for more
information on these fields.
Field | Summary | Type | DCT | Initial | Access | Modify | Rec
Proc Monitor | PP |
---|
SIOL | Simulation Value Location | INLINK | Yes | 0 | No | No | N/A | No |
SVAL | Simulation Value | DOUBLE | No | 0 | Yes | Yes | No | No |
SIML | Simulation Mode Location | INLINK | Yes | 0 | No | No | N/A | No |
SIMM | Simulation Mode | GBLCHOICE | No | 0 | Yes | Yes | No | No |
SIMS | Simulation Mode Alarm Severity | GBLCHOICE | Yes | 0 | Yes | Yes | No | No |
8. Record Support Routines
init_record
This routine initializes SIMM with the value of SIML if SIML type is
CONSTANT link or creates a channel access link if SIML type is PV_LINK.
SVAL is likewise initialized if SIOL is CONSTANT or PV_LINK.
This routine next checks to see that device support is available and a
device support read routine is defined. If either does not exist, an
error message is issued and processing is terminated.
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
9. Record Processing
Routine process implements the following algorithm:
- 1. 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.
- 2. readValue is called. See Input
Records, Chapter 3, 2 for more information.
- 3. If PACT has been changed to TRUE, the
device support read routine has started but has not completed reading a
new input value. In this case, the processing routine merely returns,
leaving PACT TRUE.
- 4. 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.
- 5. 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.
- 6. Scan forward link if necessary, set PACT FALSE,
and return.
10. Device Support
10.1. Fields Of Interest To Device Support
Each long input record must have an associated set of device support
routines. The primary responsibility of the device support routines is
to obtain a new input value whenever read_longin is called. The device
support routines are primarily interested in the following fields:
Name | Summary | Description |
---|
PACT | Processing Active | See Chapter
2, Fields Common to All Record Types for an explanation of
these fields. |
DPVT | Device Private |
UDF | VAL Undefined |
NSEV | New Alarm Severity |
NSTA | New Alarm Status |
VAL | Value Field | This field is set by device support
routines. |
INP | Input Link | This field is used by the device
support routines to locate its input. |
10.2. Device Support routines
Device support consists of the following routines:
report
report(FILE fp, paddr)
Not currently used.
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.
read_longin
read_longin(precord)
This routine must provide a new input value. It returns the following
values:
- 0: Success. A new value is placed in VAL.
- Other: Error.
10.3. Device Support For Soft Records
The Soft Channel
device support module places a value
directly in VAL.
If the INP link type is constant, then the constant value is stored into
VAL by init_record, and UDF is set to FALSE. If the INP link type is
PV_LINK, then dbCaAddInlink is called by init_record.
read_longin
calls recGblGetLinkValue to read the current
value of VAL. See Soft
Input, Chapter 3, 2.3 for more information
If the return status of recGblGetLinkValue
is zero then
read_longin sets UDF to FALSE. read_longin returns the status of recGblGetLinkValue
.
-
1. - Introduction
-
-
2. - Scan Parameters
-
-
3. - Read Parameters
-
-
4. - Operator Display Parameters
-
-
5. - Alarm Parameters
-
-
6. - Monitor Parameters
-
-
7. - Run-time and Simulation Mode Parameters
-
-
8. - Record Support Routines
-
- init_record
-
- process
-
- get_value
-
- get_units
-
- get_graphic_double
-
- get_control_double
-
- get_alarm_double
-
-
9. - Record Processing
-
-
10. - Device Support
-
- 10.1.
- Fields Of Interest To Device Support
-
- 10.2.
- Device Support routines
-
- report
-
- init
-
- init_record
-
- get_ioint_info
-
- read_longin
-
- 10.3.
- Device Support For Soft Records
-
EPICS Record Reference Manual - 19 MAY 1998
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