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Array Analog Output (aao)

The array analog output record type is used to write array data. The array data can contain any of the supported data types. The record is in many ways similar to the waveform record but outputs arrays instead of reading them. It also allows the device support to allocate the array storage.

Parameter Fields

The record-specific fields are described below, grouped by functionality.

Scan Parameters

The array analog output record has the standard fields for specifying under what circumstances the record will be processed. These fields are described in Scan Fields.

Field Summary Type DCT Default Read Write CA PP
SCAN Scan Mechanism MENU menuScan Yes Yes Yes No
PHAS Scan Phase SHORT Yes Yes Yes No
EVNT Event Name STRING [40] Yes Yes Yes No
PRIO Scheduling Priority MENU menuPriority Yes Yes Yes No
PINI Process at iocInit MENU menuPini Yes Yes Yes No

Write Parameters

These fields are configurable by the user to specify how and where to the record writes its data. The OUT field determines where the array analog output writes its output. It can be a hardware address, a channel access or database link, or a constant. Only in records that use soft device support can the OUT field be a channel access link, a database link, or a constant. Otherwise, the OUT field must be a hardware address. See Address Specification for information on the format of hardware addresses and database links.

Fields related to array writing

The DTYP field must contain the name of the appropriate device support module. The values in the array referenced by are written to the location specified in the OUT field. (If the OUT link is a constant, no data are written.) NELM specifies the maximum number of elements that the array can hold, while FTVL specifies the data type of the elements (follow the link in the table below for a list of the available choices).

Field Summary Type DCT Default Read Write CA PP
DTYP Device Type DEVICE Yes Yes Yes No
OUT Output Specification OUTLINK Yes Yes Yes No
NELM Number of Elements ULONG Yes 1 Yes No No
FTVL Field Type of Value MENU menuFtype Yes Yes No No

Operator Display Parameters

These parameters are used to present meaningful data to the operator. They display the value and other parameters of the waveform either textually or graphically.

Fields related to Operator Display

EGU is a string of up to 16 characters describing the units that the array data measures. It is retrieved by the get_units record support routine.

The HOPR and LOPR fields set the upper and lower display limits for array elements referenced by the VAL field. Both the get_graphic_double and get_control_double record support routines retrieve these fields.

The PREC field determines the floating point precision with which to display the array values. It is used whenever the get_precision record support routine is called.

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 DOUBLE Yes Yes Yes No
LOPR Low Operating Range DOUBLE Yes Yes Yes No
PREC Display Precision SHORT Yes Yes Yes No
NAME Record Name STRING [61] No Yes No No
DESC Descriptor STRING [41] Yes Yes Yes No

Alarm Parameters

The array analog output record has the alarm parameters common to all record types.

Monitor Parameters

These parameters are used to determine when to send monitors placed on the VAL field. The APST and MPST fields are a menu with choices "Always" and "On Change". The default is "Always", thus monitors will normally be sent every time the record processes. Selecting "On Change" causes a 32-bit hash of the VAL field buffer to be calculated and compared with the previous hash value every time the record processes; the monitor will only be sent if the hash is different, indicating that the buffer has changed. Note that there is a small chance that two different value buffers might result in the same hash value, so for critical systems "Always" may be a better choice, even though it re-sends duplicate data.

Record fields related to Monitor Parameters

Field Summary Type DCT Default Read Write CA PP
APST Post Archive Monitors MENU aaoPOST Yes Yes Yes No
MPST Post Value Monitors MENU aaoPOST Yes Yes Yes No
HASH Hash of OnChange data. ULONG No Yes Yes No

Menu aaoPOST

These are the choices available for the APST and MPST fields

Index Identifier Choice String
0 aaoPOST_Always Always
1 aaoPOST_OnChange On Change

Run-time Parameters

These parameters are used by the run-time code for processing the array analog output record. They are not configured using a configuration tool. Only the VAL field is modifiable at run-time.

VAL references the array where the array analog output record stores its data. The BPTR field holds the address of the array.

The NORD field holds a counter of the number of elements that have been written to the output,

Field Summary Type DCT Default Read Write CA PP
VAL Value DOUBLE[] No Yes Yes Yes
BPTR Buffer Pointer NOACCESS No No No No
NORD Number elements read ULONG No Yes No No
OMSL Output Mode Select MENU menuOmsl Yes Yes Yes No
DOL Desired Output Link INLINK Yes Yes Yes No

The following steps are performed in order during record processing.

Fetch Value

The OMSL menu field is used to determine whether the DOL link field should be used during processing or not:

  • If OMSL is supervisory the DOL field are not used. The new output value is taken from the VAL field, which may have been set from elsewhere.
  • If OMSL is closed_loop the DOL link field is read to obtain a value.

Note: The OMSL and DOL fields were added to the aaoRecord in Base 7.0.7.

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 written through SIOL. 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 Output Simulation Fields for more information on simulation mode and its fields.

Field Summary Type DCT Default Read Write CA PP
SIML Simulation Mode Link INLINK Yes Yes Yes No
SIMM Simulation Mode MENU menuYesNo No Yes Yes No
SIOL Simulation Output Link OUTLINK Yes Yes Yes No
SIMS Simulation Mode Severity 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

static long init_record(aaoRecord *prec, int pass)

If device support includes init_record(), it is called.

Checks if device support allocated array space. If not, space for the array is allocated using NELM and FTVL. The array address is stored in the 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. VAL 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 write routine is defined. If either does not exist, an error message is issued and processing is terminated

process

static long process(aaoRecord *prec)

See "Record Processing" section below.

cvt_dbaddr

static long cvt_dbaddr(DBADDR *paddr)

This is called by dbNameToAddr. It makes the dbAddr structure refer to the actual buffer holding the result.

get_array_info

static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)

Obtains values from the array referenced by VAL.

put_array_info

static long put_array_info(DBADDR *paddr, long nNew)

Writes values into the array referenced by VAL.

get_units

static long get_units(DBADDR *paddr, char *units)

Retrieves EGU.

get_prec

static long get_precision(DBADDR *paddr, long *precision)

Retrieves PREC if field is VAL field. Otherwise, calls recGblGetPrec().

get_graphic_double

static long get_graphic_double(DBADDR *paddr, struct dbr_grDouble *pgd)

Sets the upper display and lower display limits for a field. If the field is VAL 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_disp_limit = HOPR
lower_disp_limit = LOPR

get_control_double

static long get_control_double(DBADDR *paddr, struct dbr_ctrlDouble *pcd)

Sets the upper control and the lower control limits for a field. If the field is VAL 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_ctrl_limit = HOPR
lower_ctrl_limit = LOPR

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. Call device support write routine write_aao.
  3. If PACT has been changed to TRUE, the device support read routine has started but has not completed writing the new value. In this case, the processing routine merely returns, leaving PACT TRUE.
  4. 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 APST or MPST are Always or if the result of the hash calculation is different.
    • NSEV and NSTA are reset to 0.
  5. Scan forward link if necessary, set PACT FALSE, and return.


Device Support

Fields Of Interest To Device Support

Each array analog output record record must have an associated set of device support routines. The primary responsibility of the device support routines is to write the array data value whenever write_aao() 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
NSEV New Alarm Severity MENU menuAlarmSevr No Yes No No
NSTA New Alarm Status MENU menuAlarmStat No Yes No No
OUT Output Specification OUTLINK Yes Yes Yes No
NELM Number of Elements ULONG Yes 1 Yes No No
FTVL Field Type of Value MENU menuFtype Yes Yes No No
BPTR Buffer Pointer NOACCESS No No No No
NORD Number elements read ULONG No Yes No No

Device Support Routines

Device support consists of the following routines:

report

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.

init

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

long init_record(dbCommon *precord)

This routine is optional. If provided, it is called by the record support init_record() routine.

get_ioint_info

long get_ioint_info(int cmd, 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.

write_aao

long write_aao(dbCommon *precord)

This routine must write the array data to output. It returns the following values:

  • 0: Success.
  • Other: Error.

Device Support For Soft Records

The Soft Channel device support module is provided to write values to other records and store them in arrays. If OUT is a constant link, then write_aao() does nothing. In this case, the record can be used to hold arrays written via dbPuts. If OUT is a database or channel access link, the array value is written to the link. NORD is set to the number of items in the array.

If the OUT link type is constant, then NORD is set to zero.