put to disabled records and monitors

[Dirk Zimoch <dirk.zimoch@psi.ch>]

Hi folks,

A colleague of mine has seen the following strange effect:

If a disabled (DISA=1) record is written then monitors do not show the 
change. To be exact: If the VAL field of a passive record is modified 
multiple times, then a monitor shows only the first change. But if the 
record is scanned periodically, or any other field with pp(TRUE) has 
been written before, then even the first change is not shown. However, a 
caget can confirm that the value has changed.

Even when the record is re-enabled (DISA=0), the monitors do not update 
before the record processes the next time.

Other fields than the VAL field are not affected, all of their 
modifications are immediately shown by monitors.

So it seems if any attempt has been made to process a disabled record, 
then any later modification of the VAL field and only the VAL field does 
not trigger a monitor.

Is this the correct behavior? IMHO no. It leads to inconsistent displays 
for the same value. As for any other field, people also want to see any 
change that someone else makes on the VAL field.

The problem appeared when a epid record had to be configured (KP, KI, 
and KD set, as well as the setpoint VAL), before is is activated. Other 
displays did not show the modified setpoint. I could confirm that the 
problem is not limited to the epid record but affects standard base 
record like ao as well.

The code in question seems to be dbPut in dbAccess.c:

    /* Propagate monitor events for this field, */
    /* unless the field field is VAL and PP is true. */
    pfldDes = paddr->pfldDes;
    isValueField = dbIsValueField(pfldDes);
    if (isValueField) precord->udf = FALSE;
    if (precord->mlis.count &&
        !(isValueField && pfldDes->process_passive))
        db_post_events(precord, paddr->pfield, DBE_VALUE | DBE_LOG);

What about changing this to

    if (precord->mlis.count &&
        !(isValueField && pfldDes->process_passive &&
          precord->disa != precrod->disv))
        db_post_events(precord, paddr->pfield, DBE_VALUE | DBE_LOG);

or skip the whole test for VAL and do

    if (precord->mlis.count)
        db_post_events(precord, paddr->pfield, DBE_VALUE | DBE_LOG);

?

Any opinions?

Dirk