Perform measurements on saved waveforms

[Brian_Beal]

I am using a PCI-5122 to capture waveforms, then I am saving them to file using the "Write Waveforms to File" VI.  I want to now read those waveforms from the file and perform various measurements on them, particularly the same measurements that are available using the "niScope Fetch Measurement" VI.  The standard waveform processing VIs are limited in the measurements.  Can I perform the same measurements on a stored waveform as on a "real" waveform fetched from the digitizer?

[DFGray]

What version of LabVIEW are you using?  The base version does not have all the analysis VIs.  Anything above base should have all the functionality of the fetch measurement VI, although the naming conventions can be a bit confusing.  What did you want to do?

[Brian_Beal]

I have the Professional Development System for Labview 8.5.  The Fetch Measurement VI has a long list of measurements that I can chose from.  I want to get those same measurements from the waveforms that I have stored to a file.

[lab_boy]

hi Brian,

You can do post processing on the stored waveform after you have accquired but you would require to write your own code inorder to do the same.

-lab

[Brian_Beal]

What do you mean by write my own code?  At what level?  Element by element?

[DFGray]

You can find VIs to do these functions in the Signal Processing palette.  Most are in the Waveform Measurements subpalette of Signal Processing.  I have attached a VI which uses one of these to measure the high and low levels and the amplitude of a signal.  It assumes an LVM formatted file containing a single waveform.

[Brian_Beal]

I have no problem using the available waveform measurement functions on my saved waveforms.  I want to be able to use the same measurements that are available from the NiScope FetchMeasurement VI.

[Dennis_Knutson]

Looking at the NI-Scope function reference, it seems that all of the measurement functions are designed to first capture a waveform and none allow you to input external data.

[Brian_Beal]

Dennis-

That is correct.  I don't want to use the Fetch Measurement VI for my analysis of stored waveforms, but I want to be able to perform the same measurements that are available in that VI.  I can only find some of them in the Waveform library.

Brian

[Dennis_Knutson]

Brian,

I understand what you want to do but I just don't think you can use the NI-Scope driver to do perform any measurements on the data from a file.

Since I suspect that NI uses a common code base for all of their analysis/measurement functions (in drivers such as NI-Scope and programming languages such as LabVIEW or CVI), you can probably reproduce all of the scope measurement with a bit of code. Are there any in particular that you need?