Long Input Record (longin)
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.
Parameter Fields
The record-specific fields are described below, grouped by functionality.
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.
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.
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.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
VAL |
Current value |
LONG |
Yes |
Yes |
Yes |
Yes |
|
INP |
Input Specification |
INLINK |
Yes |
Yes |
Yes |
No |
|
DTYP |
Device Type |
DEVICE |
Yes |
Yes |
Yes |
No |
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 Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
EGU |
Engineering Units |
STRING [16] |
Yes |
Yes |
Yes |
No |
|
HOPR |
High Operating Range |
LONG |
Yes |
Yes |
Yes |
No |
|
LOPR |
Low Operating Range |
LONG |
Yes |
Yes |
Yes |
No |
|
NAME |
Record Name |
STRING [61] |
No |
Yes |
No |
No |
|
DESC |
Descriptor |
STRING [41] |
Yes |
Yes |
Yes |
No |
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 HYST field controls hysteresis to prevent alarm chattering from an input signal that is close to one of the limits and suffers from significant readout noise.
The AFTC field sets the time constant on a low-pass filter that delays the reporting of limit alarms until the signal has been within the alarm range for that number of seconds (the default AFTC value of zero retains the previous behavior).
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. Alarm Fields lists the fields related to alarms that are common to all record types.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
HIHI |
Hihi Alarm Limit |
LONG |
Yes |
Yes |
Yes |
Yes |
|
HIGH |
High Alarm Limit |
LONG |
Yes |
Yes |
Yes |
Yes |
|
LOW |
Low Alarm Limit |
LONG |
Yes |
Yes |
Yes |
Yes |
|
LOLO |
Lolo Alarm Limit |
LONG |
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 |
LONG |
Yes |
Yes |
Yes |
No |
|
AFTC |
Alarm Filter Time Constant |
DOUBLE |
Yes |
Yes |
Yes |
No |
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.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
ADEL |
Archive Deadband |
LONG |
Yes |
Yes |
Yes |
No |
|
MDEL |
Monitor Deadband |
LONG |
Yes |
Yes |
Yes |
No |
Run-time 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) will monitors be 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 |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
LALM |
Last Value Alarmed |
LONG |
No |
Yes |
No |
No |
|
ALST |
Last Value Archived |
LONG |
No |
Yes |
No |
No |
|
MLST |
Last Val Monitored |
LONG |
No |
Yes |
No |
No |
Simulation Mode Parameters
The following fields are used to operate the record in simulation mode.
If SIMM (fetched through SIML) is YES, the record is put in SIMS severity and the value is fetched through SIOL (buffered in SVAL). SSCN sets a different SCAN mechanism to use in simulation mode. SDLY sets a delay (in sec) that is used for asynchronous simulation processing.
See Input Simulation Fields for more information on simulation mode and its fields.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
SIML |
Sim Mode Location |
INLINK |
Yes |
Yes |
Yes |
No |
|
SIMM |
Simulation Mode |
MENU menuYesNo |
No |
Yes |
Yes |
No |
|
SIOL |
Sim Input Specifctn |
INLINK |
Yes |
Yes |
Yes |
No |
|
SVAL |
Simulation Value |
LONG |
No |
Yes |
Yes |
No |
|
SIMS |
Sim mode Alarm Svrty |
MENU menuAlarmSevr |
Yes |
Yes |
Yes |
No |
|
SDLY |
Sim. Mode Async Delay |
DOUBLE |
Yes |
-1.0 |
Yes |
Yes |
No |
SSCN |
Sim. Mode Scan |
MENU menuScan |
Yes |
65535 |
Yes |
Yes |
No |
Record Support
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_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.
readValue is called. See “Input Records” for more information.
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.
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 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 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:
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
|---|---|---|---|---|---|---|---|
PACT |
Record active |
UCHAR |
No |
Yes |
No |
No |
|
DPVT |
Device Private |
NOACCESS |
No |
No |
No |
No |
|
UDF |
Undefined |
UCHAR |
Yes |
1 |
Yes |
Yes |
Yes |
NSEV |
New Alarm Severity |
MENU menuAlarmSevr |
No |
Yes |
No |
No |
|
NSTA |
New Alarm Status |
MENU menuAlarmStat |
No |
Yes |
No |
No |
|
VAL |
Current value |
LONG |
Yes |
Yes |
Yes |
Yes |
|
INP |
Input Specification |
INLINK |
Yes |
Yes |
Yes |
No |
Device Support Routines
Device support consists of the following routines:
long report(int level)
This optional routine is called by the IOC command dbior and is passed the
report level that was requested by the user.
It should print a report on the state of the device support to stdout.
The level parameter may be used to output increasingly more detailed
information at higher levels, or to select different types of information with
different levels.
Level zero should print no more than a small summary.
long init(int after)
This optional routine is called twice at IOC initialization time.
The first call happens before any of the init_record() calls are made, with
the integer parameter after set to 0.
The second call happens after all of the init_record() calls have been made,
with after set to 1.
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.
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” 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.