RE: How to tag soft channels as undefined/disconnected

["Lionberger, Carl A." <lionbergerca@ornl.gov>]

For a project where I had a python program updating soft PVs, I wrote a timeout device support to use instead of the soft channel device support.  It times out and sets the PV invalid if a new value was not put to it within the timeout period since the last put. The C++ application just wouldn't put the value to the PV if the instrument data was invalid, and then the PV would go invalid without further action.  When valid data became available, the application would put it to the PV and the PV status would go normal again.

Carl

Carl Lionberger
Instrument Data Acquisition and Controls
Spallation Neutron Source
________________________________________
From: tech-talk-bounces@aps.anl.gov <tech-talk-bounces@aps.anl.gov> on behalf of Kellee Summers <ksummers@lbto.org>
Sent: Tuesday, August 12, 2014 7:02 PM
To: tech-talk@aps.anl.gov
Subject: How to tag soft channels as undefined/disconnected

Hi All,

We have set up an EPICS R3.14.12.4 database of pure software channels
(on a Linux system) so that we can use the alarm handler. The channel
values are being driven by a C++ software application that reads our
instrument data.   When the instrument data is stale (determined by an
out-of-date timestamp), I would like to
set the channels to UDF so that the alarm state is INVALID.

The SEVR and STAT alarm fields are non-modifiable.  I tried setting the
UDF field but it didn't give me a disconnected channel.

Do I need to modify the record processing?

Suggestions?

Thanks