Alarm properties with reference to UDT parameters

Hello all!

Until recently I’ve configured “Active Pipeline” in my tags with a reference to a UDT parameter for my tags. I created a parameter called Database with the string value MU01, and could refer to the active pipeline MU01/Pri1 by using the expression {Database}/Pri1.

In later version… somewhere between 8.1.3 and latest version of Ignition, that expression stopped working. It seems like a referance to a UDT parameter no longer works with my previous expression as {Database} now counts as null. The UDT parameter still contains the stringed value of MU01. I created a memory tag with the same stringed value, and put that into my expression, still with the old syntax, still didn’t work> {StringTag}/Pri1

Then it occured to me, you may have changed the tag property expressions to work in the same manner as expressions in general. Changing the expression to {StringTag}+“/Pri1” seemed to do the trick, and tbh it all makes sense.

This will however cause an issue whenever we want to upgrade our customer projects.

The question is, was this change intentional? Is it not longer possible to refer to UDT parameters in the Alarm Properties?

Hi Hans,

Does the expression {Database} + "/Pri1" not work for you? There is in fact a bug where the Expression UI for alarm properties is missing UDT Parameter reference dropdown button and is currently being addressed. However, this should not stop you from being able to use the expression I mentioned above.

Thanks for your reply :slight_smile:

As I mention in my post, that specific expression works fine. My question is rather, was that a planned change, meaning I have to update all my projects with the “new” expression?