Intermittent OPC Issues

Ignition
1

We have a setup with an OPC connection to our DCS/PCS setup. Generally speaking, this OPC connection has been stable but following a recent upgrade to our PCS server, we've encountered a lot of issues on this OPC connection.

I'll see the following OpcUaSubscribtionSynchronizer warning:

Error setting MonitoringMode.Reporting for 5412 items on subscription=tag-group-ans_default: status=Bad_CommunicationError, description=A low level communication error occurred.

I can actually browse the tags in Status/OPC Connections/Client/Nodes & everything looks as expected there, with the tags showing a Good status code, while this issue is active.

But, if I browse the tags themselves, I'll see bad statuses on all of the OPC tag values.

Now, I've found a workaround that generally works. I'll export all of my tags, I'll bulk replace the OPC server path in the tag configuration & I'll replace it with a new OPC connection to that same endpoint. This does actually work.

Interesting behavior I noted is that if I use tag browser, I can browse a point & I can read a point, but if the issues is active on the OPC connection, I can't subscribe to that point. That's kind of what led me down the path of creating a new OPC connection to begin with & with a new, identical (outside of the name) OPC connection, I could do everything, including subscribe.

This would be all fine I suppose if this was a one-off issue, but it seems to be that something occurs on the control system side on occasion and we end up re-encountering this error.

I'm kind of stumped on how to genuinely resolve this so I'm hoping maybe something here sounds familiar to someone?

2

I had a similar issue before and someone told me to reset my OPC connection which helped resolve that issue for me.

3

Appreciate the suggestion. Assuming you basically just mean to save changes to the connection to restart it? Unfortunately that doesn’t seem to ever resolve it for me. I’ve tried restarting ignition services, restarting the server just for good measure, nothing. Quite literally the only thing I can get to resolve it is to create a whole new OPC connection and then point my tags to the new connection.

The problem seems to be with the PCS/DCS/ control system. It seems to trigger the issue when we reboot that or restart services for OPC I believe, but it’s pretty flaky. Just hoping I can figure out some way to better cope with the issue on the Ignition side of the house if possible ultimately!

4

Go into your Gateway Webpage > Connections > OPC Connections. Then clicked on the 3 dots on the right and click "Disable" and "Enable" again to restart the OPC Connection (if that make sense). I tried uploading a picture of it but an error kept popping up.

5

Thanks again for the suggestion!

So I actually encountered the same failover related issue again & tried this but unfortunately it didn't work. It was enough to reset the connection and the connection would show connected, but upon a deeper look, all of the tags remained in a bad status.

I actually ended up opening up a ticket for this one to investigate this though & I did want to make sure the resolution was posted up on here.

Ultimately, all we ended up doing to clear this issue was to restart the OPC-UA module itself. It's a bit of an oddity to me though because I'd tried rebooting the server & I'd tried restarting the ignition services (net stop / net start igntion). None of that had ever cleared the issue but this did.

Seemingly, the old connection name, once it dropped, would sort of become corrupted. I would be unable to subscribe to points within it, but I could read points under it. I could delete it & make a new connection with the same name later & it would not work once it reassumed the old name. I could take that same connection, with the 'new' name & I would be able to subscribe to points from within it. After an explicit restart of the module itself though, all these issues seem to have resolved themselves & I can no longer create any of these issues :zany_face: