Hi,
I have a question about OPC tags. I have a gateway (Ignition 8.3.3) that is reading tags from an OPC Server, the OPC Server is Top Server / Kepware, and the issue is that some tags are in a quality status that is not good, it is Uncertain_LastKnownValue, but if I check the OPC server, the tags are in Good quality.
In Ignition, there are tags in good quality too, the tags in Uncertain_LastKnownValue seem to change their values not too often, I don't know if this low frequency changes is the reason of the Uncertain_LastKnownValue quality, so my question is if this could be the reason and if it is, how can we handle it, is there any configuration settings that controls that behavior?, because the tags due to the process itselft have a slow rate of changes.
Best regards,
Daniel Fernandez.
Would you be willing to periodically read a fresh value? I'll have to take a look to see when exactly they become Uncertain_LastKnownValue in Ignition, but very slow rate of change does sound like a probably factor.
How many tags are we talking about? I'm imagining worst case scenario you could script checking for any Uncertain tag values and then reading a fresh value. Alternatively, maybe you could put the slow tags in a different tag group with more appropriate settings?
Just spitballing. I suspect someone with more knowledge will come along an answer this, but if not, I'll circle back with more info after I've done some digging on my side.
Well how it seems, nobody came along, but sadly whe have the same issue in 8.3.3. We have quite many and different opc tags that frequently have this issue. The status is good again, when the tags changes. But we also have for example opc tags, that are written by us with a quality good check and these stay uncertain until manuall restart.
Is there already any fix known?
Greetings
You should open a support ticket.
If there's a blip in the connection between the Ignition and the source OPC UA server, all of the subscribed tags will get Uncertain_LastKnownValue. The only way they can become good quality after the connection is restored is to receive a new good quality value. Ignition OPC UA client tries to recover this automatically upon reconnect.
In later versions of Ignition, I think there were some changes to how the Ignition OPC UA client recovers. I'm not 100% confident that they address the issue you two are describing, but it may be worth updating to the latest 8.3.x to give it a try. If that doesn't work, support can help us narrow down to something more specific.
As mentioned before, another workaround could be to manually read each of the tags. Another potential workaround could be to disable/re-enable the connection behind the tags. Both of these workarounds are a bit heavy-handed, so I'd recommend trying the latest 8.3, then reaching out to support if you're still having issues.