Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Fri, 30 Jul 2004 11:32:38 -0600

Hello John,

> The program already works, but after a time (~ 2 h) the 
> monitor-functions just disconnect and the program abort.

One possible cause of trouble in a single threaded program would be not
calling ca_pend_event() periodically although this theory does not fit well
with the 2 hr delay before the disconnect.

To get a better understanding of your issue some additional details will be
helpful:
o What version of EPICS are you running?
o What operating system are you using when this occurs?
o You mention that "monitor-functions just disconnect". Did monitor updates
cease to occur, did the channel receive a disconnect callback, or did the
software terminate in some way?
o You mention that that the program aborts. Was there a failure? For example
a bus error, or did the program abort because of a fatal severity channel
access exception? If so, then please copy the output from the exception
message into an email reply. If the program died in some other way then
please elaborate on the circumstances. 
o When this problem is occurring do you get a successful response from "ping
<IOC name>" executed on the same host as yor CA client?
o You might also try "telnet <IOC name>" as that will confirm TCP
connectivity from the same host as the CA client.
o Finally, when the program is in this disconnected state, does rebooting
the IOC cause the monitor updates to start up again (this is assuming that
the software didn?t abort)?

> I had looked into iocinf.c and i think there is a counter, who
> disconnect the monitor-function. Why?

The CA client library monitors connectivity with the servers and notifies
the application program when connectivity has been lost. The library watches
for beacons from the server. If a beacon does not show up for
EPICS_CA_CONN_TMO seconds then the library sends an are-you-there message to
the IOC. If there isn?t a prompt response then the application receives
disconnect notification. The details on all of this are in the CA reference
manual.

Sorry to answer your question with questions of my own, but I will need more
details in order to determine what is occurring there and if it is a bug.

Sorry about the delay responding.

Jeff

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> Sent: Thursday, July 29, 2004 2:34 AM
> To: tech-talk
> Subject: problem with the monitor-function (c++)
> 
> Hi all members,
> 
> my name is John Kettler and i am a beginner.
> 
> I use the Channel Access (epics) to communicate with a VME Crate. For
> this i put monitor-functions with ca_search_and_connect, ca_pend_io,
> ca_add_event and ca_pend_event. The program already works, but after a
> time (~ 2 h) the monitor-functions just disconnect and the program
> abort. I can restart the program without any problem.
> When i reboot the Crate the program works on, so i can say it's no
> problem with the network connection.
> 
> The message i get is the following:
> 
> CA.Client.Diagnostic.....................................
> 	Message: "Network conncetion lost"
> 	Serverity: "Warning" Context: "test1:5064"
> 	Source File: ../iocinf.c Line Number:1504
> ..........................................................
> 
> I had looked into iocinf.c and i think there is a counter, who
> disconnect the monitor-function. Why?
> 
> So, if you have an answer please let me know.
> 
> John
> 
> ---
> John Kettler			[email protected]
> DELTA - Univesität Dortmund 	http://www.delta.uni-dortmund.de

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System