Two soft device support modules are provided. One reads values directly into VAL. The other reads values into RVAL, which is then converted just like raw values obtained from hardware device support modules. If soft device support with a constant INP link is chosen, then the VAL field can be modified via dbPuts.
-------------------------------------------------------------- Field Type DCT Initial Access Modify Rec Proc PP Monitor -------------------------------------------------------------- VAL DOUBLE No 0 Yes Yes Yes Yes INP INLINK Yes 0 No No N/A No PREC SHORT Yes 0 Yes Yes No No LINR CVTCHOICE Yes 0 Yes Yes No Yes EGUF FLOAT Yes 0 Yes Yes No Yes EGUL FLOAT Yes 0 Yes Yes No Yes EGU STRING Yes null Yes Yes No No HOPR FLOAT Yes 0 Yes Yes No No LOPR FLOAT Yes 0 Yes Yes No No AOFF FLOAT Yes 0 Yes Yes No Yes ASLO FLOAT Yes 1 Yes Yes No Yes SMOO FLOAT Yes 0 Yes Yes No No HIHI FLOAT Yes 0 Yes Yes No Yes LOLO FLOAT Yes 0 Yes Yes No Yes HIGH FLOAT Yes 0 Yes Yes No Yes LOW FLOAT Yes 0 Yes Yes No Yes HHSV GBLCHOICE Yes 0 Yes Yes No Yes LLSV GBLCHOICE Yes 0 Yes Yes No Yes HSV GBLCHOICE Yes 0 Yes Yes No Yes LSV GBLCHOICE Yes 0 Yes Yes No Yes HYST DOUBLE Yes 0 Yes Yes No No ADEL DOUBLE Yes 0 Yes Yes No No MDEL DOUBLE Yes 0 Yes Yes No No ROFF LONG No 0 Yes Yes No Yes ESLO DOUBLE No 1 Yes No No No LALM DOUBLE No 0 Yes No No No ALST DOUBLE No 0 Yes No No No MLST DOUBLE No 0 Yes No No No PBRK NOACCESS No 4 No No No INIT SHORT No 0 Yes No No No LBRK SHORT No 0 Yes No No No RVAL LONG No 0 Yes Yes Yes Yes ORAW LONG No 0 Yes No No No SIOL INLINK Yes 0 No No N/A No SVAL DOUBLE No 0 Yes Yes No No SIML INLINK Yes 0 No No N/A No SIMM GBLCHOICE No 0 Yes Yes No No SIMS GBLCHOICE Yes 0 Yes Yes No No --------------------------------------------------------------
----------------------------------------------------------------------------------------- Name Summary Description ----------------------------------------------------------------------------------------- VAL Value Field Unless INP is a constant link and the device support module specifies no conversion, this is the value resulting from the record being processed. If INP is a constant, then VAL is initialized to the INP value but can be changed dynamically via dbPutField or dbPutLink. INP Input Link This field is used by the device support routines to obtain input. For soft analog records it can be a constant, a database link, or a channel access link. PREC Display Precision Precision with which to display VAL and OVAL. This field is used by record support to supply a value when get_precision is called. LINR Conversion Type No conversion, linear and breakpoint table conversion are supported. EGUF Engineering Units These fields are used to perform linear conversions. It is Full the responsibility of the device support routines to use EGUF and EGUL to compute ESLO and ROFF. EGUF and EGUL must be set by the user to the engineering units corresponding to the high and low ADC limits. For example if the ADC has a range of -10 to +10 Volts, then EGUF must be the engineering units value corresponding to 10 volts and EGUL to -10 volts. If a linear conversion is specified, recAi uses ESLO, ROFF, and EGUL to convert the raw value to engineering units according to the formula: VAL = (RVAL + ROFF)*ESLO + EGUL EGUL Engineering Units Low ROFF Raw Value Offset ESLO Slope for Linear Conversions EGU Engineering Units An ASCII string of up to 16 characters describing the engineering units. This field is used by record support to supply a units description string when get_units is called. HOPR High Operating These fields determine the upper and lower display limits Range for graphics displays and the upper and lower control limits for control displays. The fields are used by record support to honor calls to get_graphic_double or get_control_double. LOPR Low Operating Range AOFF Adjustment Offset These fields are adjustment parameters for the raw input values. They are applied to the raw data value returned by the device support routine before any other conversions are performed. ASLO Adjustment Slope SMOO Smoothing Factor The converted data value is subjected to the following algorithm: val = newvalue * (1 - smoo) + oldvalue * smoo SMOO should have a value between 0 and 1, with 0 meaning no smoothing and 1 meaning ultimate smoothing (in fact, the data value will never change). HIHI Hihi Alarm Limit These fields specify the alarm limits and severities. HIGH High Alarm Limit LOW Low Alarm Limit LOLO Lolo Alarm Limit HHSV Hihi Alarm Severity HSV High Alarm Severity LSV Low Alarm Severity LLSV Lolo Alarm Severity HYST Alarm Deadband These parameters specify hysteresis factors for triggering monitors by a call to db_post_event or monitor callbacks, i.e. callbacks specified by calls to caAddEvent or dbAddEvent. A monitor will not be triggered until VAL changes by more than the specified amount. ADEL Archive Deadband MDEL Monitor, i.e. value change, Deadband LALM Last Alarm Monitor These fields are used to implement the hysteresis factors Trigger Value for monitor callbacks. ALST Last Archiver Monitor Trigger Value MLST Last Value Change Monitor Trigger Value INIT Initialize This field is used by record support to perform initialization for LBRK and for smoothing. LBRK Last Breakpoint Index of last breakpoint interval. LBRK is used to perform conversions via breakpoint tables. PBRK Address of PBRK is used to perform conversions via breakpoint Breakpoint Table tables. RVAL Raw Value RVAL is the raw data value obtained by the device support routine. Unless the device support routine returns value requests that no conversion should be performed, the record support routine converts this value to engineering units. ORAW Old Raw Value ORAW is used to decide if monitors should be triggered for RVAL at the same time monitors are triggered for changes in VAL. SIMM Simulation Mode Simulation mode process variables. Refer to Chapter 3 Section "Simulation Mode" on page 11 for more information. SIML Simulation Mode Location SVAL Simulation Value SIOL Simulation Value Location SIMS Simulation Mode Alarm Severity -----------------------------------------------------------------------------------------
This routine next checks to see that device support is available and a device support read_ai routine is defined. If either does not exist, an error message is issued and processing is terminated.
INIT is then set to TRUE.
If device support includes init_record, it is called.
If the device support routine special_linconv exists, it is called.
INIT is set TRUE. This causes PBRK, LBRK, and smoothing to be reinitialized.
upper_alarm_limit = HIHI upper_warning_limit = HIGH lower_warning_limit = LOW lower_alarm_limit = LOLO
val = val* ASLO + AOFFIf the conversion algorithm is linear, the raw value is converted via the equation:
val = val * ESLO + EGULIf the conversion is via a breakpoint table, the new value is obtained.
if SMOO equal to 0. or INIT is True, VAL = val else VAL = val * (1 - SMOO) + Previous_value * SMOOSince VAL is now defined, the last step is to set UDF to FALSE.
--------------------------------------------------------------------------------------------- Name Summary Description --------------------------------------------------------------------------------------------- PACT Processing Active See Chapter 2 Section "Database Common: Field Descriptions" on page 4 for descriptions. DPVT Device Private UDF VAL Undefined NSEV New Alarm Severity NSTA New Alarm Status VAL Value This field is used by device support only if it obtains a value already converted to engineering units. See RVAL below. INP Input Link This field is used by the device support routines to locate its input. EGUF Engineering Units Full These fields are used to calculate ESLO. Note that these fields correspond to the high and low hardware limits. EGUL Engineering Unit Low ESLO Slope These fields are used for linear conversions from raw to engineering units. The device support routines must calculate these fields unless they obtain values already in engineering units. ROFF Raw Offset RVAL Raw Value It is the responsibility of the device support routine to give this field a value. If the device support routine obtains a value already in engineering units, it should place the value in VAL and return a value of 2. ---------------------------------------------------------------------------------------------
report (FILE fp, paddr)Not currently used.
init()This routine is called once during IOC initialization.
init_record (precord)This routine is optional. If provided, it is called by the record support init_record routine.
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_ai(precord)This routine must provide a new input value. Asynchronous device support routines will return with PACT set to TRUE. If PACT is TRUE, the process routine will just return and not continue processing. When the asynchronous routine completes, it can call process which will again call read_ai. Because PACT is still TRUE read_ai knows that this is a request to retrieve the data obtained by the previous call. When finished, read_ai should set PACT to FALSE and return one the following values:
special_linconv(precord,after)This routine is called whenever any of the fields LINR, EGUF, EGUL or ROFF is modified.
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_ai calls recGblGetLinkValue to read the current value of VAL. See Chapter 3 Section "Soft Input" on page 10 for details.
If the return status of recGblGetLinkValue is zero, then read_ai sets UDF to FALSE. The status of recGblGetLinkValue is returned.
If soft support is chosen, the following fields become meaningless: LINR, EGUF, EGUL, ESLO, ROFF, AOFF, ASLO, and SMOO. The read_ai routine always returns a value of 2 which means don't convert.
If raw soft support is chosen, the fields EGUF and EGUL become meaningless. ESLO and ROFF always have their default values of 1 and 0.