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<== Date ==> <== Thread ==>

Subject: Re: CA monitoring weirdness for status/severity
From: "Hogben, Colin H" <Colin.Hogben@ukaea.uk>
To: Mark Rivers <rivers@cars.uchicago.edu>, "Johnson, Andrew N." <anj@aps.anl.gov>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Mon, 07 Aug 2017 15:30:55 +0100
On 07/08/17 14:22, Mark Rivers wrote:

You will see that the HIGH field has the PP attribute.  This means that writing to the HIGH field causes the record to  process.

OK, that explains why the record got processed and we no longer get UDF from caget or a new camonitor.

However, the HIGH field does not have Rec Proc Monitor, so writing to the HIGH field does not cause monitor events to be posted.  So your original camonitor program does not get an event.  However, if you run camonitor again it connects to the channel and does get the new timestamp and status.

Well, I do get an update for the monitoring of the HIGH field, but the status/severity passed in the update are the previous state - I'm guessing the update of HIGH is sent out before the record gets processed.

My aim of my bridge is: given an arbitrary PV name, monitor the PV to obtain its value and/or an indication as to whether the value is invalid or unavailable. Based on my experiments and what you guys have said, my current understanding is thus:

* If the PV represents the VAL field. then the status & severity in updates may be used; in effect, this is effectively a short-cut to getting the VAL, STAT and SEVR fields at the same time.

* If the PV represents any other field, the status and severity in an update are meaningless noise and should be disregarded.

Is that a reasonable approximation?
--
Colin Hogben
Professional Software/Control Engineer
CODAS & IT Department
United Kingdom Atomic Energy Authority
Culham Science Centre
Abingdon
Oxfordshire
OX14 3DB
Tel : 01235 464948
Web: www.gov.uk/ukaea

Replies:
Re: CA monitoring weirdness for status/severity Johnson, Andrew N.
References:
CA monitoring weirdness for status/severity Hogben, Colin H
Re: CA monitoring weirdness for status/severity Johnson, Andrew N.
Re: CA monitoring weirdness for status/severity Hogben, Colin H
RE: CA monitoring weirdness for status/severity Mark Rivers

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