Experimental Physics and
Industrial Control System

"Kasemir, Kay" <[email protected]> · Fri, 12 Aug 2016 20:06:12 +0000

Hi:

> On 08/12/2016 03:48 PM, Zhang, Dehong wrote:
>> Is it possible that the channel access server may send duplicates,
>> or re-transmit the same messages?  Specially when congested?

Not sure what level this question addresses.

Assuming the question is:

If you run “camonitor some_PV_name”, will you see the same message over and over?
I.e. same time stamp, same value?

-> That should not happen.

The record will only send an update when the value changes.
Unless you have an analog record with MDEL = -1, in which case you’ll see a message whenever the record processes, even if the value remains the same. The time stamp would still differ, though.

If you have MDEL=-1, and your timing configuration is broken, i.e. your IOC is configured to get the time from somewhere, and that keeps sending the same time of day, then yes, you might see the same value with the same time stamp.

-Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System