Error reading OPC Client Connection on Project while good quality on OPC Quick Client

I’ve tried reading a OPC server connection from a tag in the project designer. On the gateway I get a good quality value, for example


But when I added to the project as a OPC tag from the OPC Browser in the same path, I get an error

I tried change the rate time of the tag group, but the error persists. My project is set to read/write gateway mode. I tried fixing the issue by moving from version 8.0.6 to 8.0.7 and 8.0.8. Any advice? What am I missing?

In the Log Viewer area of the gateway you can change the logging levels by clicking on the little gear icon and searching for a logger name.

Find the loggers for OpcUaSubscriptionModel and OpcUaSubscriptionSynchronizer set them to TRACE. Then go ahead and disable/enable those tags or edit/save the connection or something. See if any log messages about creating monitored items appear soon after that.

This are the results from trace the log

Sir. What does BadTooManyMonitoredItems = 0x80DB0000 means? it seems there’s the problem

Yes, the server is telling you there’s already too many monitored items.

Do you have a lot of other tags subscribed against this server? Are they in the same tag group?

Is this an S7-1500 you’re connected to?

Actually yes. To a PLCSIM Advanced 3. Running a S7-1500

Ok, well try moving some tags to another tag group and see if that helps. Otherwise you will just have to reduce the number of monitored items. Subscriptions from systems other than Ignition do count against whatever limits there are.

This document has some info about what limits might be in place:


For now, I created a clean Ignition Gateway 8.0.8. Only thing I did was connect to the OPC server in a remote IP, running an S7-1500 Instance. And the tag group for the first OPC tag I created is running default tag group settings.

Ok, thanks I´ll check it out and keep you online

Each tag group in Ignition corresponds to an OPC UA subscription made on the server. If there turns out to be some limit to the number of Monitored Items the server will let you add to a given Subscription then moving some tags to a new tag group will create a new Subscription on the server and start adding Monitored Items for those tags to the new Subscription instead.

There may also be a limit to the total number of Monitored Items across all Subscriptions. In that case there’s not much else you can do.

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Thanks for your guide. It was solved by raising the number of subscriptions on TIA, and making a reconnection to the OPC server on the gateway.

Thumbs up for you!