TagChange behavior

Hi again, I’ve been testing the way that Gateway TagChange Scripts behaves when the tag changes several times before the first thread finish. So, the result was that the threads runs serial and the triggers accumulate into a stack like a LIFO stack (Last Input First Output), is that rigth?

I.e. tag values were: 6 then 7 then 8 and finally 9

and the threads respond to 6 then 9 then 8 and finally 7

I just want to know if that is the way it works, thanks!


No, when the changes occur, the event scripts get submitted to a multi-thread executor to be run as quickly as possible. The results could depend on how your testing, but I don’t think there’s any reliable way to ensure the ordering.

In Ignition 7.7, in addition to the current method of defining event scripts, you’ll be able to define tag change events directly on tags, and I know that these execute in order.