Cycle Average and RMS

Question

Hi,
Please look at PDF for pictures included.
I’ve got an existing labview code made in LV2009. Running fine where installed.
The problem is when running it now on current verison 2011.
The main problem is the Cycle Average an RMS function.
When running from labview help ; example code:
Pulse and Transition Measurements.vi
Her below run as initial setup whit no noise, a clean sinus.
With noise added ..the calculations vary a little.
The problem arises when the signal is outside of the referencelevels:
For example with a lot of noise . Still the same raw signal, men now the noise std dev is increased from 0,1 to 0,4
Same result form small signals
The program runs a while, but again the error message comes.
When running a the code on our own system :
Trough a IIR filter:
Lowpass: , signal below null
Bandpass not quite good either..
In any case I cannot get away the error message:
Error -20308 occurred at  "NI_MAPro.lvlib:Cycle Average and RMS 1 chan.vi:2" when called from "NI_MAPro.lvlib:Cycle Average and RMS N chan.vi:1"  (waveform index 0 of 2)
ossible reason(s):
Analysis:  The waveform did not cross the mid reference level enough times to perform this measurement. Check the signal length, reference levels, and ref level units.
Have tried to adjust any referense level without any sucsess.. 
What could be wrong??
Attachments:
labviewerrors.pdf ‏621 KB

Answer 1

Hello Josens,
Can you let me know if this issue/questions is still active?
Can you provide the code you used in NI LabVIEW  2009 and the code you use in NI LabVIEW 2011?
Can you also provide the data sets you used to verify the behavior of both versions of the code?
Also keep in mind the error message you got from your VI:
"The waveform did not cross the mid reference level enough times to perform this measurement. Check the signal length, reference levels, and ref level units."
Have you compared the data sets you are providing/acquiring at the old installation (with NI LabVIEW 2009) with the data sets you are acquiring/providing in your newer installation (with NI LabVIEW 2011).
Based on the errors it seems like these are/might be different (eg. new/other sensors) .
You also use the default values for the settings of the "Cycle Average and RMS.VI".
If these default values don't suffice for the measurements with your new sensors, then this might also be causing issues.
If the code and the acquired data you are using in both set-ups is exactly the same (aside from the LabVIEW version), then I would not expect a difference in behavior.
However, this requires the knowledge of the data you're using for your calculation.
Kind Regards,
Thierry C - Applications Engineering Specialist Northern European Region - National Instruments
CLD, CTA
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