What to look for in a new UDT element that is not updating?

This is on 8.1.2

I have an existing UDT that defines a block of data in my PLC, and I have an instance of that UDT running in a project.

I added a new item to the data in the PLC. Then I modified the UDT definition to add the new data item. And the new item has shown up in the instance. But the value doesn’t seem to be changing in the instance.

Inside the PLC I can modify the values other elements of the UDT and see the values change in the instance.

I also created a simple OPC tag that points directly to the same item and I can see value changes in that instance.

I have compared my new tag with pre-existing tags of the same data type and I can’t see any configuration differences. The quality of the instance of the new tag is good, but the timestamp seems to be stuck around the time that I created it. (And yes the tag is enabled in the UDT definition and the deadband is suitable) and no errors are being reported anywhere. And I can’t write to the new tag (it is defined as readonly in the PLC anyway).

I know that I am missing something, but what could it be? Or do I have to simply do something as mundane as restarting the project?


As I was making my test on a cloned virtual machine I just recreated the VM and added teh new item back to the UDT. And now it all works :angry: