Sometimes OPC Browser in the designer gives error after a long wait from gateway. Whereas the OPC client seems to be working fine. It gets triggers from the server for subscriptions. What could be the reason? Do we need to restart the OPC server module on gateway?
Will restating of OPC Server not affect the running Ignition SCADA application and PLC’s connected and the plant? How safe is it to restart the OPC-UA module in a running plant?
(I am working on a trial version of Ignition).
The errors occur because the browse takes too long, but as to why it would happen you would need to look at the gateway logs for more information.
Restarting the server/module will temporarily interrupt reads, writes, and subscriptions, so it’s not necessarily a “safe” thing to do unless that short interruption is okay.
OK. But is there a single OPC UA server per Igintion (physical) server to which the PLC’s are also connected to (in addition to any other opc client application that we connect to?.
In that case restarting OPC UA server will also impact the PLC’s and the entire plant operation! Or restarting OPC UA server not affect PLC’s and plant performance except for a brief period when communication between the two are reestablished? During this period the PLC’c continue to operate with their last set points? Is restarting OPC UA server (or for that matter Ignition server) a fail safe operation or it needs a plant shutdown?
Setpoints or anything else do not get reset. No writes happen. The only thing that happens when you restart the UA server is it stops polling values from any of the PLCs it’s connected to until it restarts and subscriptions are made again.
Ok got it. So even if you pull the plug between the OPC UA server (or Ignition server) it would not only cause momentary communication loss and things will continue to work as before but eventually it will re establish connectivity and normalcy. (if things are designed properly to restart).
