Limits

[Clint Eastwood]

1) In Teststand you can select units prefix of say "megohm" or "kilohms" when doing a numeric limit test.  Apparently Teststand doesn't evaluate these units.  If I say my tests has to be > than 1 "megohm" and my step result is 10 the test passes.  if I put the zeros in, the seq shows  ( for example) 1000000 megohms..thats not right !!  Anyone know how to resolve this??

2) How do you account for resistance measurement that is open (infinite) and your requirements say ">100 meg".  When you do a numeric limit test on an open you get "NAN" in Teststand.  NAN is an open and > 10 meg but fails because, I think, of the comparison of nan and >10 meg.

Thanks !

[James_Grey]

1) Teststand doesn't evaluate units. Units are just informative labels. This might be a good thing if you want to have perhaps, units of Mangos, and you don't want TestStand to misinterpret that as Mega-Angos

2) You are getting NaN for open because that is what your code-module or instrument-driver is returning. To test for for NaN in TestStand, use a EQ comparison with a limit of NaN.

[Clint Eastwood]

So if I return NAN from my coded module ( LABVIEW) to Teststand how do I test for say > 10 MEG Ohms??  If I select ">10000000" as the limits and TS returns NAN it fails. 

[James_Grey]

If you return NAN from your LabVIEW module to TestStand, then NAN is the only value TestStand has to work with. NaN is neither greater or less than another number so greater than and less than comparisons always return false.

If the problem is that sometimes you get > 10MOhms and sometimes you get NaN, and you want both to pass, you could do a large number of things. A few simple options are:

1) Check for NaN in your code module and return INF instead. INF > 10000000 evaluates to true.

2) Change your Numeric Limit Test Data Source from

Step.Result.Numeric

to

Step.Result.Numeric == Nan ? Inf : Step.Result.Numeric

3) Store the measurement in a local and test it with two limit test steps, one for == NaN and one for > 10MOhms. Put a precondition of value == NaN on the first and a precondition of value != NaN on the second.

[Clint Eastwood]

Thanks James.