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MES-OPC-PLC question

I just received an IQ for an Interface from our MES system to a shop floor PLC. The PLC connects to an OPC server. The way this IQ works is that a known is input to the MES and then read at the PLC, and therefore, the executor can deduce that the registers have been mapped correctly. Has anybody ever seen this type of testing for a PLC before? I took one look at the testing and asked why they were testing the OPC server so many times?

Hi Meyert,

So a value is inputted to the MES interface and that value is verified at the PLC level to ensure the value is correct. That seems logical.

The PLC connects to the OPC server. I assume this is tested at the IQ stage when the PLC was validated? Is this how the executer can deduce that the registers have been mapped correctly?

I’m not sure if I understand correctly is this IQ testing the MES system or trying to test the PLC’s connections.

“I took one look at the testing and asked why they were testing the OPC server so many times”

How is this being tested so many times?

Is there not another IQ for the PLC.

Sorry for all the questions I just want to make sure I understand this corectly.

Is the whole point of the IQ testing the interface from the MES to the PLC and not the PLC to the OPC server.

Regards