Error in expression not being displayed

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 :frowning:

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. :slight_smile: