How do you tell when one scan ends and the next one starts?

[carleton_hanson]

Goal: To use the built in acquire process display n scan template to get fft of one input and a dc value of the rest using a AT-MIO-16XE card in Labview 6.1.

Issue: Read one scan create fft (amplitude vs frequency), Max & Min and Dc values of the rest.

How to determine when one scan is finished and the next one starts, so I can reset the Max/min and basic DC/RMS object and the min max of the FFT amplitude at ever scan .

Inputs:

Fast - Dynamic pressure - need to plot amplitude verses frequency

Slow - temperatures and pressures - just need average Dc value

currently solving these other issues,

FFT does not function properly (only looking at only one half of spectrum)

need to convert 'save to spreadsheet' to save to string to file (to much overhead opening file every time)

Thanks for your help

[mross]

QUOTE (carleton_hanson @ Mar 12 2008, 11:02 AM)

Goal: To use the built in acquire process display n scan template to get fft of one input and a dc value of the rest using a AT-MIO-16XE card in Labview 6.1.

Issue: Read one scan create fft (amplitude vs frequency), Max & Min and Dc values of the rest.

How to determine when one scan is finished and the next one starts, so I can reset the Max/min and basic DC/RMS object and the min max of the FFT amplitude at ever scan .

Inputs:

Fast - Dynamic pressure - need to plot amplitude verses frequency

Slow - temperatures and pressures - just need average Dc value

currently solving these other issues,

FFT does not function properly (only looking at only one half of spectrum)

need to convert 'save to spreadsheet' to save to string to file (to much overhead opening file every time)

Thanks for your help

Sounds like the scanning business you propose is not needed and the root problem is FFT "not working." You should solve the FFT. I don't ever mess with that so someone else will have to chime in.

If you unpack the write to sprdsht vi you can pull the open and close out of the loop. However, I don't understand why you are writing to the spreadsheet every loop iteration. Why not keep the data in an array (shift register and build array) and write it out when you are done so there is no file accessing at all while doing the AI Read.

Mike