Limit Test - Can I use it how I'm trying to use it?

[aham312]

I'm working on a project in SignalExpress and I'm trying to use Limit test as a way to analyze a voltage signal. There are two things I want to test: 1.) I need to sheck if the magnitude of the signal remains in a certain range over any given oscillation. I can physically replicate a "too high" and "too low" signal, but I'm not sure how to save the signal and use it as a limit. 2.) Ineed to check if the signal moves from a specified low value to a specified high value in a specified amout of time. Is this doable with a limit test? 

Thanks,

Andy

[GiantDeathRobot]

Hi Andy,

Just to check, are the ranges constant over time, or are they changing? If you can physically replicate the signals, you can record those as a .lvm file and one of the options for setting up the Limit Test is that you can load a signal to be a limit. Select that, and it will ask you for a .lvm file that contains the limit signal. Pick the upper/lower limit signal you previously recorded, and you should be good to go. There is more information on this in the Configuration section of the Limit Test help. (http://zone.ni.com/reference/en-XX/help/371268L-01/expresswb/limit_test/)

As for hitting values in a specified amount of time, you might be able to do a really hacky version of that with a user defined signal. (Raise the minimum value over a certain amount of time to just below your specified high.) But a limit test is for checking to make sure a signal falls within a certain voltage range, not if it hits certain values over time. In general SignalExpress is for doing fairly simple and out of the box measurements. Tweaking it like that would probably end up being more difficult than doing an analysis like that in LabVIEW, which would give you more flexibility.

GiantDeathRobot