Array Analog Input (aai)
The array analog input record type is used to read array data. The array data can contain any of the supported data types. The record is in many ways similar to the waveform record. It allows, however, 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 input record has the standard fields for specifying under what circumstances the record will be processed. These fields are described in Scan Fields.
Read Parameters
These fields are configurable by the user to specify how and from where the record reads its data. The INP field determines from where the array analog input 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.
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.
Alarm Parameters
The array analog input 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.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
---|---|---|---|---|---|---|---|
APST |
Post Archive Monitors |
MENU aaiPOST |
Yes |
Yes |
Yes |
No |
|
MPST |
Post Value Monitors |
MENU aaiPOST |
Yes |
Yes |
Yes |
No |
|
HASH |
Hash of OnChange data. |
ULONG |
No |
Yes |
Yes |
No |
Run-time Parameters
These parameters are used by the run-time code for processing the array analog input 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 input 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 read into the array.
Field |
Summary |
Type |
DCT |
Default |
Read |
Write |
CA PP |
---|---|---|---|---|---|---|---|
VAL |
Value |
DOUBLE[NELM] |
No |
Yes |
Yes |
Yes |
|
BPTR |
Buffer Pointer |
NOACCESS |
No |
No |
No |
No |
|
NORD |
Number elements read |
ULONG |
No |
Yes |
No |
No |
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. 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 |
Record Support
Record Support Routines
init_record
static long init_record(aaiRecord *prec, int pass)
If device support includes an init_record()
routine it is called, but unlike
most record types this occurs in pass 0, which allows the device support to
allocate the array buffer itself.
Since EPICS 7.0.5 the device support may return AAI_DEVINIT_PASS1
to request
a second call to its init_record()
routine in pass 1.
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 BPTR.
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
process
static long process(aaiRecord *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:
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.
Call device support read routine
read_aai()
.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.
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.
Scan forward link if necessary, set PACT FALSE, and return.
Device Support
Fields Of Interest To Device Support
Each array analog input record 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_aai()
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 |
|
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’s init_record()
routine in
pass 0.
The device support may allocate memory for the VAL field’s array (enough space
for NELM elements of type FTVA) from its own memory pool if desired, and store
the pointer to this buffer in the BPTR field.
The record will use calloc()
for this memory allocation if BPTR has not been
set by this routine.
The routine must return 0 for success, -1 or a error status on failure.
Since EPICS 7.0.5 if this routine returns AAI_DEVINIT_PASS1
in pass 0, it
will be called again in pass 1 with the PACT field set to AAI_DEVINIT_PASS1
.
In pass 0 the PACT field is set to zero (FALSE).
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.
read_aai
long read_aai(dbCommon *precord)
This routine should provide a new input value. It returns the following values:
0: Success.
Other: Error.
Device Support For Soft Records
The Soft Channel
device support is provided to read values from other
records via the INP link, or to hold array values that are written into it.
If INP is a constant link the array value gets loaded from the link constant by
the record_init()
routine, which also sets NORD.
The read_aai()
routine does nothing in this case.
If INP is a database or channel access link, the read_aai()
routine gets a
new array value from the link and sets NORD.