I'd like to give here some inputs for a discussion about EPICS software for
CLAS:
I recently found out that some thoughts has already been given to the interface
between EPICS and coda. It can be found in the coda 1.4 manual at the appendix
D. According to these specifications, a single process ( CEIMON ) should take
care of the communication. It could involve some record additions to some EPICS
database. Does anyone have a more precise idea about that? Is it still valid?
I would like also to express my concerns about error messages. In EPICS, there
is a logging error message facility that could be used in case of unexpected
situation. This is different from an alarm condition because it concerns
possible hardware problems like I/O failure or driver problem, things like that.
Is this facility going to be used?
Generally, what kind of alarm scheme does the EPICS software developped in HALL
B should implement?
For example : if hardware problems are detected, in which alarm condition the
corresponding records should be put? What do you want from an alarm handler so
that it can be coded in device supports?
What informations are desirable from the photon cryogenic target? Actually, the
EPICS interface is planned to be a database with 3 records : Pressure,
Temperature and status (target ok, target not ok). Is it enough to interface
with the acquisition system in case of a failure from the target ( in this case
the acquisition has to stop)? What report back would you like to have knowning
that the target system will stop itself if a problem is detected.
regards,
Thierry.