Error in NI's 'Threshold 1-D array'?

Question

I was using this VI to find zero crossings and when I use one in my VI it seems to work fine. If I add a second only one of them works. It switches between which one actually works. I looked at the old version of the program that I am rewriting, it was written in LabVIEW 6i, and found a VI someone created that said it fixxed an error in teh Threshold 1-D array. My question is if this was known in 6i why wouldnt it be fixxed by now? Maybe other people havent came across this or I am just wrong. Just curious either way. I will attach the VI that claims to fix this problem
Attachments:
Threshold.vi ‏27 KB

Answer 1

OK, the only known problem for "threshold array" is documented in the online help: "... and it might return incorrect data if threshold y is less than the value at start index". Does this apply to your data?
I don't think it has anything to do with the number of calls on the diagram, but is an inherent limitation. The array must start with values below the desired threshold.
Your "fixed" VI basically searches the array until the data goes from negative to positive, then starts the "threshold array" at the index of the last found negative value, ensuring that the limitation does not apply. For some reason it jumps through quite a few uneccessary hoops doing so. All the stuff with bundling is not needed, it does not make sense. I have included
a cleaned-up version below. See if this works for you. (llb contains both VIs, I also did a few minor changes to the main vi for simplicity).
As a more general comment, I think there might be better ways to determine a phase shift. How does your data typically look like? (e.g. amount of noise, presence of other frequencies, DC offsets, etc. all will cause serious problems with this simplistic approach).
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Attachments:
Not_NotWorking.llb ‏32 KB