OPC DA Server stopped and Supervision Time Out.
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The OPC framework in System 800xA is constantly monitoring the health of the various OPC servers it is connecting to.
In this case your OPC DA server does not respond on GetStatus() in a timely fashion - after 30 seconds timeout, the OpcDA Connector Service will abort itself, restart and try to connect to the non-responsive OPC DA server again.
1. Identify the OPC DA server in trouble
2. Fault trace the OPC DA server
Depending on what OPC server brand and type, your options will vary. E.g. if you would be using the OPC server for AC 800M, the C:\ABB Industrial IT Data\Control IT Data\OPC Server for AC 800M\LogFiles\session.log(s) would be one of the first things I'd check.