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<== Date ==> <== Thread ==>

Subject: monitor subscription in areaDetector
From: "Pearson, Matthew R." <pearsonmr@ornl.gov>
To: "tech-talk@aps.anl.gov list" <tech-talk@aps.anl.gov>
Date: Fri, 27 Jan 2017 17:25:56 +0000
Hi,

In areaDetector, for when we append NDAttribute data to NDArray objects, we have a class that can set up monitors on PVs. When a monitor event happens we record the data for use by the next NDArray object. However, we were setting a monitor callback handler for every connection event. This can result in multiple monitors being setup if the IOC that hosts the PV being monitored has been restarted a few times (resulting in a multiple connection events in the areaDetector IOC).

I was able to fix this in the same was as camonitor.c handles this, by using a flag to indicate that we’ve already connected (and set up a monitor) to a PV. Is this the most appropriate method to handle this? In the CA reference manual I see that there are functions like ca_clear_channel() and ca_clear_subscription() that we could possibly use on a disconnection event.

Cheers,
Matt


Data Acquisition and Control Engineer
Spallation Neutron Source
Oak Ridge National Lab







Replies:
Re: monitor subscription in areaDetector Kasemir, Kay
Re: monitor subscription in areaDetector Andrew Johnson

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