OPC communication problem


I have a problem with an OPC server that I guess that it’s faulty, these are the symptoms:

  1. One of my SQL Bridge group starts to fail, the involved tags have an OPC Quality=Unknown

  2. When I go to OPC Servers connections it says that it’s connected
    (It is a local OPC server installed in the same PC as Ignition)

  3. I edit the connection to disable the connection and then enter again to re-enable it

    and after that everything becomes OK again. (Quality=Good and group running)

These are my settings for this connection:

This problem arises 2 or 3 times a day but only with this OPC connection. Other OPC connections in my configuration work without problems.

I’d like to know if there is a configuration option that can make the “re-connection” automatically

Thank you


Does the tag quality problem only occur when trying to start the group? What is the warning that the group reports?

By disabling and re-enabling the opc connection, your basically resubscribing the items (and physically reconnecting, which is a fairly substantial too, it’s possible the OPC server could be completely restarting as a result of this). The question is why the values are going bad in the first place - do they get set to bad quality somewhere along the line and never come back, or do they simply never get their first value when the group first subscribes to them.

I’m not familiar with that OPC server, so I’m not sure what it supports. Since the connection shows “connected”, I doubt any failure is being detected. If it’s just a small number of tags, you might be able to get around this by simply switching your group’s “opc data mode” to “read” instead of subscribe. Otherwise, we’ll have to figure out why it’s happening in order to see if it’s something we can influence.


Ok, the problem was that the OPC Server “Saab Tank Radar” had a limited License. Once the full license was installed, the problem was solved for good.

Thank you