Experimental Physics and
Industrial Control System

Matthieu Bec <[email protected]> · Wed, 28 May 2008 13:24:51 -0400


Hi all,
I setup an epics x86-ioc attached to a tcp server, the ioc listens to
known size packets from the server and fills an epics waveform record
with the data. The packets are ~21kB and update at ~50Hz, our clients
have EPICS_CA_MAX_ARRAY_BYTES set.
One of our user reported seeing intermittent corrupt values, the rate is
highly unpredictable: one bad sample every few seconds to few minutes.
I setup two minimal test clients to check what was happening -
1. one polling ca_get (which is how my user implemented his client app)
2. another using ca_monitor
(1) reproduce the problem while (2) appears trouble free.
I remember reading a post on tech-talk about string/array not being
buffered and thought that might explain the issue with (1), something
like concurrent read/write maybe. Could this be the issue?
Also, I was wondering if (2) is guaranteed to be consistent? Do I need
to put something else in place so every single waveform update will be
consistent.
Thanks,
Matthieu
--
Matthieu Bec              Gemini Observatory
Tel: +56 51 205785        c/o AURA, Casilla 603
Fax: +56 51 205650        La Serena, Chile

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System