How does the OPC-UA driver determine if it is connected?

Ignition
1

Trying to run down a communications issue, and I came across something I wanted to clarify. I have a machine running a KEPServerEX v4 driver connected to a PLC. I also have a device set up in the OPC-UA driver connected to the same PLC. I am having some communications dropouts with this PLC that have nothing (I think) to do with the drivers, but it has brought something to light. If I have my project using the OPC-UA driver, it will occasionally disconnect then reconnect. I am also seeing this behavior in the KEPServer. However, if I delete the tag using the OPC-UA driver, it never shows disconnected.

So, now that I’ve explained all that, I’ll come to my question. Does the OPC-UA driver occasionally go out and verify the connection to the device, or once it does the initial connection, does it assume the connection is still alive until a communications error occurs?

Thanks.

2

What you are probably seeing is a read on the driver that is timing out 3 times in a row. When this happens the driver will disconnect and then reconnect.

When you delete the tag you always see the driver state as CONNECTED because there isn’t actually anything going on.

3

OK, that’s what I was thinking, but I wanted to make sure my observations were correct. Thanks.