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 record-specific fields are described below, grouped by functionality.
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". In addition, "Scanning Specification" explains how these fields are used. Note that I/O event scanning is only supported for those card types that interrupt.
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. See "Address Specification" for information on the format of hardware addresses and a database links.
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
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_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  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  No Yes No No DESC Descriptor STRING  Yes Yes Yes No
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" 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 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
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" for a complete explanation 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
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 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
The following fields are used to operate the long input in the simulation mode. See "Fields Common to Many Record Types" for more information on these fields.
Field Summary Type DCT Default Read Write CA PP SIOL Sim Input Specifctn INLINK Yes Yes Yes No SVAL Simulation Value LONG No Yes Yes No SIML Sim Mode Location INLINK Yes Yes Yes No SIMM Simulation Mode MENU (menuYesNo) No Yes Yes No SIMS Sim mode Alarm Svrty MENU (menuAlarmSevr) Yes Yes Yes No
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.
See next section.
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.
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.
Sets the following values:
upper_alarm_limit = HIHI upper_warning_limit = HIGH lower_warning_limit = LOW lower_alarm_limit = LOLO
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.
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 consists of the following routines:
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.
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.
This routine is optional. If provided, it is called by the record support
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.
This routine must provide a new input value. It returns the following values:
0: Success. A new value is placed in VAL.
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
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