Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Thu, 30 Aug 2012 11:36:23 +0200

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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System