Dear all,
Fragments from Ralph and Deb's postings...
>>> We might consider one additional subtlety
>>
>> Just one?
>>
>>> for those of us who use STAT and/or
>>> SEVR, particularly to display value with a color rule that indicates these
>>> values. If an output record had readback but was not processed, would it
>>> affect STAT and/or SEVR values. Right now I think these are usually UDF
>>> and INVALID respectively until the record is processed.
>>
>> Good point. As the record is defined after reading back the value,
>> UDF/INVALID is inappropriate. Would you think we need to have another
>> status that announces that the value has been read back and is valid, but
>> the record hasn't been processed yet? Or would that be too subtle a
>> difference to be signalled?
The existing output record device support that I have looked at (_not_
an exhaustive test) looks something like this (from devBoXVme220.c)...
status = xy220_read(pvmeio->card,pbo->mask,&value);
if(status == 0) pbo->rbv = pbo->rval = value;
else status = 2;
.
return(status);
...so if the readback succeeds, RVAL is set to the readback value and a
zero status is returned, which (for bo anyway) will do...
if(status==0) {
if(pbo->rval==0) pbo->val = 0;
else pbo->val = 1;
pbo->udf = FALSE;
} else if (status==2) status=0;
...so RVAL will be converted to VAL and UDF will be cleared. If the readback
failed, then a status of 2 is returned, no conversion to VAL occurs, and UDF
is left unchanged.
So I think that the UDF/INVALID side of things is already handled.
William
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