epics/epics-base
0
0
Fork 0
Code Issues Pull Requests Projects Wiki Activity

waveform: Update POD, describe BUSY field

Browse Source
This commit is contained in:
Andrew Johnson
2021-07-21 11:06:34 -05:00
parent 16c3202992
commit 7a6aa3edd1
1 changed files with 19 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
modules/database/src/std/rec/waveformRecord.dbd.pod
View File

@@ -120,9 +120,18 @@ 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 holds a counter of the number of elements that have been read
into the array. It is reset to 0 when the device is rearmed. The BUSY field
indicates if the device is armed but has not yet been digitized.
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 C<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 C<read_wf()> routine would clear BUSY which
informs the record's C<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.
=fields VAL, BPTR, NORD, BUSY
@@ -367,14 +376,14 @@ Other: Error.
=head3 Device Support For Soft Records
The C<<< Soft Channel >>> device support module is provided to read values from
other records and store them in arrays. If INP is a constant link, then read_wf
does nothing. In this case, the record can be used to hold arrays written via
dbPuts. If INP is a database or channel access link, the new array value is read
from the link. NORD is set to the number of items in the array.
other records and store them in the VAL field. If INP is a constant link, then
C<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.
This module places a value directly in VAL.
If the INP link type is constant, then NORD is set to zero.
If the INP link type is constant, VAL is set from it in the C<init_record()>
routine and NORD is also set at that time.
=cut