Say you have tag A and tag B in a folder, with tag A using tag B in an expression. If you move the location of tag B, tag A’s expression now does not evaluate, but no error is shown - it freezes at the last good value. I would have thought it should immediately show a ‘Not_Found’ error. If you start and stop the Ignition service, it does show a ‘Not_Found’ error.
Well, it depends on the expression. If the expression cannot evaluate the quality of the tag should be bad.
It should be, but it isn’t
What data types are your two tags and what is the expression you are using?
Tags are Int4. Expression for ‘Tag A’ is{[.]Tag B}
If I then move Tag B to another folder, no error is shown for Tag A (its DataQuality is still ‘GOOD_DATA’).
We have found a bug. When you move the tag to another folder or rename it, it doesn’t cause the expression on Tag A to evaluate again since it is waiting for a value change. If you were to go into Tag A’s expression and just press OK the quality will be NOT_FOUND.
When I go into Tag A’s expression and press OK, nothing changes. Its Quality is still GOOD_DATA, even though the expression is clearly wrong - the reference to Tag B is pointing to the wrong folder.
I actually have to change something in the expression before it is re-evaluated.
Right, good point.