Expression syntax in 800xA faceplate editor
Hi... for a certain tag in 800xA, I am trying to write an expression in the faceplate editor to enable / disable a particular button. I have no problems referencing properties on that tag, but I would also like to reference a property on another tag.
The expression I'm using is accepted by the system, and the Reference tool shows references to the other tag as resolved. But when the referenced property from the other tag changes, there seems to be no effect, I'm not sure I'm referencing it properly?
I've attached a couple pictures to illustrate. Any thoughts?
The expression I'm using is accepted by the system, and the Reference tool shows references to the other tag as resolved. But when the referenced property from the other tag changes, there seems to be no effect, I'm not sure I'm referencing it properly?
I've attached a couple pictures to illustrate. Any thoughts?
Asked 4 months ago
Answers
2
> " I would also like to reference a property on another tag."
Sounds like a bad idea. In general, writing individual faceplates or worse, overriding the standard faceplates isn't a great idea. Try to stick to using object types as much as possible. If your loop logic is dependent on another tag, then this should be coded in the controller application. Complex logic like this hiding somewhere in the HMI expressions is going to cause somebody somewhere significant grief in a few years. (Source: years spent receiving significant grief)
But anyway ...
Is the referenced Tag name unique ? Duplicate tag names will break this logic. (Another good reason to stick with Object types)
Sounds like a bad idea. In general, writing individual faceplates or worse, overriding the standard faceplates isn't a great idea. Try to stick to using object types as much as possible. If your loop logic is dependent on another tag, then this should be coded in the controller application. Complex logic like this hiding somewhere in the HMI expressions is going to cause somebody somewhere significant grief in a few years. (Source: years spent receiving significant grief)
But anyway ...
Is the referenced Tag name unique ? Duplicate tag names will break this logic. (Another good reason to stick with Object types)
Answered 4 months ago
0
Rob, thanks for your response. I agree in general that overridding and customizing faceplates on a per instance level is usually not the best idea. I may still not do it, but am exploring a couple options for a unique situation. It's definitely a mixed blessing that this system seems infinitely flexible!
Answered 4 months ago
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