Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Thu, 05 Jul 2012 17:21:55 +0200

Hello,

Consider a client that subscribes for two PVs (here in particular two

fields of the same record). Now the IOC (the record support) posts

events on both fields. Is the time order of these two events preserved?

In other words, are the monitor callbacks of the client called in the

same order as the IOC calls db_post_events()?

In my particular case, I have a client (with unknown source code) that

sometimes sees value changes on two fields of the motor record, DMOV and

RRBV, in the wrong order. Thus in the DMOV callback, RRBV still has the

old value. I checked in the motor record that DMOV is always posted

after RRBV.

Is there any mechanism in EPICS that could swap the execution order or

should the problem be searched in the client?

Dirk