Bug #1556

CSS-DCM Communication Problem

Added by Martin Frank over 9 years ago. Updated over 9 years ago.

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We have observed that CSS sometimes has trouble finding information from some DCMs and displays "Disconnected."

As Ron explained to me (Martin), CSS will send out a signal over a certain port (5064?) and ask everyone on the subnet for the PV information. Whichever IOC has the information will broadcast it back. All of the IOCs are on the same subnet as novadaq-ctrl-master, so this should happen without problems. However, CSS does not find some DCMs, so we have to manually add them to the address look-up list in CSS (CSS->Preferences->CSS Core->EPICS->addr_list).

Today (7/22/11), a network switch was upgraded at NDOS and after the work was completed, CSS could not get any information from dcm-3-01-02. When I checked manually (using caget), I got the information from dcm-3-01-02, so, for some reason, the GUI was not able to retrieve that same information. I added dcm-3-01-02 to the CSS address look-up list, restarted CSS, and then everything worked fine.

It would seem that this is a CSS GUI issue, but then why did it happen right after the network switch upgrade?


#1 Updated by Martin Frank over 9 years ago

Geoff sent the following comments regarding this issue:

After upgrading a switch I would restart the gui. After the initial PV name broadcast on port 5064 the clients make a TCP/IP connection with the server hosting the PV. The EPICS channel access protocol handles reconnects automatically. There is no guarantee that the TCP/IP connection will make it through a switch upgrade. The IOCs also send broadcasts out on a different port, 5065. When a server starts it sends this broadcast so that clients with unconnected PVs know to rebroadcast their connection requests.

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