Using vision 8.1.27
I have been having communication issues between ignition and PLC. For a while I could see Good_Overload quality on some tags in the tag browser and I found 2 tags that were errored in Ignition because they did not exist in the PLC. I understand how that could cause issues since the tags will keep trying to read. I can see in the PLC diagnostic buffer that I get an error "OPC UA Server: Sampling rate could not be reached" and after deleting those two broken tags I saw an improvement in the amount of errors in the PLC. I also found some tags that were ignition expression tags that used a tag from the ignition tag browser (OPC tag) that no longer existed. I saw an improvement deleting those tags as well but I feel like there is another variable I am missing because technically the expression tags don't have an address to poll. Could those broken expression tags cause sample rate issues as well? Also, is there any message in the ignition log files I can search to see if there are more broken tags? I don't see any log messages relating to this, but when I am filtering with INFO I have a lot of data that is unrelated and it is difficult to search through. Is there a term I could search to find it? There are no logs under ERROR or WARN.
Thanks in advance!
No, those errors will be internal to Ignition.
I think you should upgrade Ignition to a version that includes the Tag Report Tool in the designer tag browser. This lets you search for tags across the system that have bad quality so you can prune them (or correct their problems).
Thank you! Yes, I have the tag report tool and I found the two broken OPC references this way but was specifically searching for OPC tags, so I didn't notice the other broken expression tags. It is strange that after deleting the expression tags I saw such a big difference in the amount of sample rate errors in the PLC. There must be something I am missing
Are you using leased tags? An expression tag that references an leased OPC tag will move that source to its leased rate. Deleting a bunch of expressions might have impacted your OPC subscriptions.
All tag groups are using Direct mode
Were there events monitoring the expressions and producing writes to the PLC?
(About out of ideas.)
What problem are you actually trying to diagnose/solve here? That you receive Good_Overload quality sometimes?
I know the good_overload status comes from the PLC and I could see there were a lot of errors for sample rate could not be reached. I can understand that the two tags I deleted in Ignition that were setup as OPC tags but no longer existed in the PLC would help with this, but after I did that I still saw a lot of sample rate errors in the PLC. Today, I only have a handful and haven't made any further changes aside from deleting tags that were expressions which I did not think would improve anything. I was trying to figure out if this would actually improve the issue? Or I have fallen down the wrong hole and am investigating something that wouldn't actually affect this.