64bit Integer Input Record (int64in)

This record type is normally used to obtain an integer value of up to 64 bits from a hardware input. The record supports alarm limits, alarm filtering, graphics and control limits.

Parameter Fields

The record-specific fields are described below.

Input Specification

These fields control where the record will read data from when it is processed:

FieldSummaryTypeDCT DefaultReadWriteCA PP
DTYPDevice TypeDEVICEYes YesYesNo
INPInput SpecificationINLINKYes YesYesNo

The DTYP field selects which device support layer should be responsible for providing input data to the record. The int64in device support layers provided by EPICS Base are documented in the "Device Support" section. External support modules may provide additional device support for this record type. If not set explicitly, the DTYP value defaults to the first device support that is loaded for the record type, which will usually be the Soft Channel support that comes with Base.

The INP link field contains a database or channel access link or provides hardware address information that the device support uses to determine where the input data should come from.

Operator Display Parameters

These parameters are used to present meaningful data to the operator. They do not affect the functioning of the record.

FieldSummaryTypeDCT DefaultReadWriteCA PP
DESCDescriptorSTRING [41]Yes YesYesNo
EGUUnits nameSTRING [16]Yes YesYesNo
HOPRHigh Operating RangeINT64Yes YesYesNo
LOPRLow Operating RangeINT64Yes YesYesNo

Alarm Limits

The user configures limit alarms by putting numerical values into the HIHI, HIGH, LOW and LOLO fields, and by setting the associated alarm severity in the corresponding HHSV, HSV, LSV and LLSV menu fields.

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 LALM field is used by the record at run-time to implement the alarm limit functionality.

FieldSummaryTypeDCT DefaultReadWriteCA PP
HIHIHihi Alarm LimitINT64Yes YesYesYes
HIGHHigh Alarm LimitINT64Yes YesYesYes
LOWLow Alarm LimitINT64Yes YesYesYes
LOLOLolo Alarm LimitINT64Yes YesYesYes
HHSVHihi SeverityMENU (menuAlarmSevr)Yes YesYesYes
HSVHigh SeverityMENU (menuAlarmSevr)Yes YesYesYes
LSVLow SeverityMENU (menuAlarmSevr)Yes YesYesYes
LLSVLolo SeverityMENU (menuAlarmSevr)Yes YesYesYes
HYSTAlarm DeadbandINT64Yes YesYesNo
AFTCAlarm Filter Time ConstantDOUBLEYes YesYesNo
LALMLast Value AlarmedINT64No YesNoNo

Monitor Parameters

These parameters are used to determine when to send monitors placed on the VAL field. The monitors are sent when the current value exceeds the last transmitted value by the appropriate deadband. If these fields are set to zero, a monitor will be triggered every time the value changes; if set to -1, a monitor will be sent every time the record is processed.

The ADEL field sets the deadband for archive monitors (DBE_LOG events), while the MDEL field controls value monitors (DBE_VALUE events).

The remaining fields are used by the record at run-time to implement the record monitoring deadband functionality.

FieldSummaryTypeDCT DefaultReadWriteCA PP
ADELArchive DeadbandINT64Yes YesYesNo
MDELMonitor DeadbandINT64Yes YesYesNo
ALSTLast Value ArchivedINT64No YesNoNo
MLSTLast Val MonitoredINT64No YesNoNo

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.

FieldSummaryTypeDCT DefaultReadWriteCA PP
SIMLSimulation Mode LinkINLINKYes YesYesNo
SIMMSimulation ModeMENU (menuYesNo)No YesYesNo
SIOLSimulation Input LinkINLINKYes YesYesNo
SVALSimulation ValueINT64No YesYesNo
SIMSSimulation Mode SeverityMENU (menuAlarmSevr)Yes YesYesNo
SDLYSim. Mode Async DelayDOUBLEYes-1.0YesYesNo
SSCNSim. Mode ScanMENU (menuScan)Yes65535YesYesNo

Record Support

Record Support Routines

The following are the record support routines that would be of interest to an application developer. Other routines are the get_units, get_graphic_double, get_alarm_double and get_control_double routines, which are used to collect properties from the record for the complex DBR data structures.


This routine first initializes the simulation mode mechanism by setting SIMM if SIML is a constant, and setting SVAL if SIOL is a constant.

It then checks if the device support and the device support's read_int64in routine are defined. If either one does not exist, an error message is issued and processing is terminated.

If device support includes init_record, it is called.

Finally, the deadband mechanisms for monitors and level alarms are initialized.


See next section.

Record Processing

Routine process implements the following algorithm:

  1. Check to see that the appropriate device support module and its read_int64in routine are defined. If either one does not exist, an error message is issued and processing is terminated with the PACT field set to TRUE, effectively blocking the record to avoid error storms.
  2. Determine the value:

    If PACT is TRUE, call the device support read_int64in routine and return.

    If PACT is FALSE, read the value, honoring simulation mode:

    • Get SIMM by reading the SIML link.
    • If SIMM is NO, call the device support read_int64in routine and return.
    • If SIMM is YES, then
      • Set alarm status to SIMM_ALARM and severity to SIMS, if SIMS is greater than zero.
      • If the record simulation processing is synchronous (SDLY < 0) or the record is in the second phase of an asynchronous processing, call dbGetLink() to read the input value from SIOL into SVAL. Set status to the return code from dbGetLink(). If the call succeeded, write the value to VAL and set UDF to 0.

        Otherwise (record is in first phase of an asynchronous processing), set up a callback processing with the delay specified in SDLY.

    • Raise an alarm for other values of SIMM.
  3. If PACT has been changed to TRUE, the device support signals asynchronous processing: its read_int64in output routine has started, but not completed reading the new value. In this case, the processing routine merely returns, leaving PACT TRUE.
  4. Set PACT to TRUE. Get the processing time stamp. Set UDF to 0 if reading the value was successful.
  5. Check UDF and level alarms: This routine checks to see if the record is undefined (UDF is TRUE) or if the new VAL causes the alarm status and severity to change. In the latter case, NSEV, NSTA and LALM are set. It also honors the alarm hysteresis factor (HYST): the value must change by at least HYST between level alarm status and severity changes. If AFTC is set, alarm level filtering is applied.
  6. Check to see if monitors should be invoked:
    • Alarm monitors are posted if the alarm status or severity have changed.
    • Archive and value change monitors are posted if ADEL and MDEL conditions (see "Monitor Parameters") are met.
  7. Scan (process) forward link if necessary, set PACT to FALSE, and return.

Device Support

Device Support Interface

The record requires device support to provide an entry table (dset) which defines the following members:

 typedef struct {
     long number;
     long (*report)(int level);
     long (*init)(int after);
     long (*init_record)(int64inRecord *prec);
     long (*get_ioint_info)(int cmd, int64inRecord *prec, IOSCANPVT *piosl);
     long (*read_int64in)(int64inRecord *prec);
 } int64indset;

The module must set number to at least 5, and provide a pointer to its read_int64in() routine; the other function pointers may be NULL if their associated functionality is not required for this support layer. Most device supports also provide an init_record() routine to configure the record instance and connect it to the hardware or driver support layer.

The individual routines are described below.

Device Support 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.

long init_record(int64inRecord *prec)

This optional routine is called by the record initialization code for each int64in record instance that has its DTYP field set to use this device support. It is normally used to check that the INP address is the expected type and that it points to a valid device; to allocate any record-specific buffer space and other memory; and to connect any communication channels needed for the read_int64in() routine to work properly.

long get_ioint_info(int cmd, int64inRecord *prec, IOSCANPVT *piosl)

This optional routine is called whenever the record's SCAN field is being changed to or from the value I/O Intr to find out which I/O Interrupt Scan list the record should be added to or deleted from. If this routine is not provided, it will not be possible to set the SCAN field to the value I/O Intr at all.

The cmd parameter is zero when the record is being added to the scan list, and one when it is being removed from the list. The routine must determine which interrupt source the record should be connected to, which it indicates by the scan list that it points the location at *piosl to before returning. It can prevent the SCAN field from being changed at all by returning a non-zero value to its caller.

In most cases the device support will create the I/O Interrupt Scan lists that it returns for itself, by calling void scanIoInit(IOSCANPVT *piosl) once for each separate interrupt source. That routine allocates memory and inializes the list, then passes back a pointer to the new list in the location at *piosl.

When the device support receives notification that the interrupt has occurred, it announces that to the IOC by calling void scanIoRequest(IOSCANPVT iosl) which will arrange for the appropriate records to be processed in a suitable thread. The scanIoRequest() routine is safe to call from an interrupt service routine on embedded architectures (vxWorks and RTEMS).

long read_int64in(int64inRecord *prec)

This essential routine is called when the record wants a new value from the addressed device. It is responsible for performing (or at least initiating) a read operation, and (eventually) returning its value to the record.

If the device may take more than a few microseconds to return the new value, this routine must never block (busy-wait), but use the asynchronous processing mechanism. In that case it signals the asynchronous operation by setting the record's PACT field to TRUE before it returns, having arranged for the record's process() routine to be called later once the read operation is finished. When that happens, the read_int64in() routine will be called again with PACT still set to TRUE; it should then set it to FALSE to indicate the read has completed, and return.

A return value of zero indicates success, any other value indicates that an error occurred.

Extended Device Support


Device Support For Soft Records

Two soft device support modules, Soft Channel and Soft Callback Channel, are provided for input records not related to actual hardware devices. The INP link type must be either a CONSTANT, DB_LINK, or CA_LINK.

Soft Channel

This module reads the value using the record's INP link.

read_int64in calls dbGetLink to read the value.

Soft Callback Channel

This module is like the previous except that it reads the value using asynchronous processing that will not complete until an asynchronous processing of the INP target record has completed.