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Bad CommFailure LimitOk (24)

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11 Apr 2016 18:12 #3981 by support
This, actually, is not a "bad" connection to the OPC server. As long as you are getting no error and therefore a non-null VTQ, the connection to the server is working fine, and the value/timestamp AND quality are as the server has sent them to us.

Therefore the primary investigation should be on the server - why is it indicating a CommFailure.

Some servers send bad quality for some time after their startup, or after an OPCGroup is created in them by the client.

Sometimes the bad qualities are provided by the server over subscriptions, while the "reads" give good data. QuickOPC initiates an additional subscription for the "reads". You may try to disable that - see www.opclabs.com/forum/reading-writing-subscriptions-property...scriptions-made-with-opc-reads .

Best regards

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11 Apr 2016 10:11 #3979 by Damian999
Occasionally when our application starts, it appears to get a "bad" connection to the OPC server.

Our application will attempt to read 2 OPC tags on startup.

So the following line will be executed
DAVtqResult[] results = _easyDaClient.ReadMultipleItems(argumentsList.ToArray());

The results show a comms error of some sort.
results[0].Vtq = {@09/03/2016 14:36:40; Bad CommFailure LimitOk (24)}

We're running Wonderware InTouch 10.5 with FS Gateway as the OPC server.

Once in every 10 times when we start Intouch and then our Application (that executes the above line) we get this error.
FS Gateway is in a “started” state.

To workaround this problem we have to restart the OPC server.. In this case FS Gateway.


Is there anything we can do to mitigate this error?

Thanks

Damian

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