The waveform record type is used to interface waveform digitizers. The record stores its data in arrays. The array can contain any of the supported data types.
The record-specific fields are described below, grouped by functionality.
The waveform record has the standard fields for specifying under what circumstances the record will be processed. These fields are listed in Scan Fields.
These fields are configurable by the user to specify how and from where the record reads its data. How the INP field is configured determines where the waveform gets its input. 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 INP field be a channel access link, a database link, or a constant. Otherwise, the INP field must be a hardware address.
Field Summary Type DCT Default Read Write CA PP DTYP Device Type DEVICE Yes Yes Yes No INP Input Specification INLINK 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 RARM Rearm the waveform SHORT Yes Yes Yes Yes
The DTYP field must contain the name of the appropriate device support module. The values retrieved from the input link are placed in an array referenced by VAL. (If the INP link is a constant, elements can be placed in the array via dbPuts.) NELM specifies the number of elements that the array will hold, while FTVL specifies the data type of the elements (follow the link in the table above for a list of the available choices).
The RARM field used to cause some device types to re-arm when it was set to 1, but we don't know of any such devices any more.
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.
Field Summary Type DCT Default Read Write CA PP EGU Engineering Units STRING  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  No Yes No No DESC Descriptor STRING  Yes Yes Yes No
EGU is a string of up to 16 characters describing the units that the waveform 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.
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.
The waveform record has the alarm parameters common to all record types. Alarm Fields lists the fields related to alarms that are common to all record types.
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
The default is
thus monitors will normally be sent every time the record processes.
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.
Field Summary Type DCT Default Read Write CA PP APST Post Archive Monitors MENU (waveformPOST) Yes Yes Yes No MPST Post Value Monitors MENU (waveformPOST) Yes Yes Yes No HASH Hash of OnChange data. ULONG No Yes Yes No
This menu defines the possible choices for
Index Identifier Choice String 0 waveformPOST_Always Always 1 waveformPOST_OnChange On Change
These parameters are used by the run-time code for processing the waveform. They are not configured using a configuration tool. Only the VAL field is modifiable at run-time.
VAL references the array where the waveform stores its data. The BPTR field holds the address of the array.
The NORD field indicates the number of elements that were read into the array.
The BUSY field permits asynchronous device support to collect array elements sequentially in multiple read cycles which may call the record's
process() method many times before completing a read operation.
Such a device would set BUSY to TRUE along with setting PACT at the start of acquisition (it could also set NORD to 0 and use it to keep track of how many elements have been received).
After receiving the last element the
read_wf() routine would clear BUSY which informs the record's
process() method that the read has finished.
Note that CA clients that perform gets of the VAL field can see partially filled arrays when this type of device support is used,
so the BUSY field is almost never used today.
Field Summary Type DCT Default Read Write CA PP VAL Value Set by FTVL No Yes Yes Yes BPTR Buffer Pointer NOACCESS No No No No NORD Number elements read ULONG No Yes No No BUSY Busy Indicator SHORT No Yes No No
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. 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 Simulation Mode Link INLINK Yes Yes Yes No SIMM Simulation Mode MENU (menuYesNo) No Yes Yes No SIOL Simulation Input Link INLINK 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
static long init_record(waveformRecord *prec, int pass)
Using NELM and FTVL space for the array is allocated. 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 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.
static long process(waveformRecord *prec)
See "Record Processing" section below.
static long cvt_dbaddr(DBADDR *paddr)
This is called by dbNameToAddr. It makes the dbAddr structure refer to the actual buffer holding the result.
static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
Obtains values from the array referenced by VAL.
static long put_array_info(DBADDR *paddr, long nNew)
Writes values into the array referenced by VAL.
static long get_units(DBADDR *paddr, char *units)
static long get_precision(DBADDR *paddr, long *precision)
Retrieves PREC if field is VAL field. Otherwise, calls
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
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
Routine process implements the following algorithm:
Each waveform record must have an associated set of device support routines. The primary responsibility of the device support routines is to obtain a new array value whenever read_wf 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 INP Input Specification INLINK 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 RARM Rearm the waveform SHORT Yes Yes Yes Yes BPTR Buffer Pointer NOACCESS No No No No NORD Number elements read ULONG No Yes No No BUSY Busy Indicator SHORT No Yes No No
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.
long init_record(dbCommon *precord)
This routine is optional. If provided, it is called by the record support
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.
long read_wf(waveformRecord *prec)
This routine must provide a new input value. It returns the following values:
Soft Channel device support module is provided to read values from other records and store them in the VAL field. If INP is a constant link, then
read_wf() does nothing. In this case, the record can be used to hold a fixed set of data or array values written from elsewhere. If INP is a valid link, the new array value is read from that link. NORD is set to the number of items received.
If the INP link type is constant, VAL is set from it in the
init_record() routine and NORD is also set at that time.