I found a similar discussion here: Excluded Attribute in Analyses
Currently, it seems that there is no straight forward way to do this and the 'IsExcluded' function is not yet available.
Furthermore, the functions in a Formula DR are much more limited compared to an AF Analysis.
In the short term, I would say that the likelihood of an elegant solution using a Formula DR is very slim.
Is there any particular reason why you prefer to use a Formula DR?
If you are open to using an AF Analysis, I feel that there is a possible immediate solution.
During my tests, I noticed the following behaviour:
If the data in your PI Point never assumes the "No Result" digital state, then you could try the following logic:
If 'MyAttribute' = "No Result" Then <insert EXCLUDED logic> Else If BadVal('MyAttribute') Then <insert BAD logic> Else <insert GOOD logic>
Just FYI, I also tried using the same strategy with a Formula DR but I couldn't find a way to make it recognize the "No Result" digital state.
Again, this seems to be a limitation with the Formula DR.
Thanks for your detailed answer!
I guess I was hoping to use a Formula DR as this is a templated element, of which there are many and i'm doing a simple "is element faulted" check based on a number of fault tags. Unfortunately a number of the elements inheriting from this template have not got all the alarms (and no it can't be broken down nicely into an inherited template style).
I went through and excluded these attributes on the instances however then my formula (which checks for bad values on the real fault tags) fails.
I feel the Formula Data Reference is due for an upgrade
Thanks again for your answer.