Fourier Transform and the DAQ Assistant

Hi,
I'm trying to take the fourier transform of a analog voltage measurement in Labview 8.6 and I'm having a problem with the data.
The measurement is an anaolog input voltage signal taken using the USB-6211 box. I am acquiring the signal on ports 15 and 16 (differential) with the DAQ Assistant at a rate of 5KHz, 200 samples. The setup works perfect thankfully, and a very nice waveform plot is generated on the VI. I would now like to add a fourier transform of this plot to do some frequency analysis.
I found the FFT function, but when I tried to add the DAQ output to it, I got an error about dynamic data. It takes me to a screen which I don't understand about dynamic data conversion, and I'm not sure what to do from this point. My FFT graph is basically just a flat white line, which is wrong.
How can I just take the basic fourier transform of a waveform in this setup?

Hi
Your thinking is not bad. You have only some scaling problems. You may toy with the vi I am sending. Change the log/linear control and see the result.
You will find all information you need here http://zone.ni.com/devzone/cda/tut/p/id/4541 and http://zone.ni.com/devzone/cda/tut/p/id/4541. The dt value is the reciprocal of the sample frequency(1/x) The unit is second, and it will give you the time interval between two samples.
Also note how I use the "Dynamic To Waveform Array.vi" to convert the dynamic data. This VI is not documented by NI, but you find it here ...vi.lib\express\express shared\transition.llb\Dynamic To Waveform Array.vi
Good luck
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
Attachments:
Spectrum Analyzer.vi ‏32 KB

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Sorry, forgot to attach the end result. Note I did have errors come up, they may have been due to no DAQ cards in my PC.
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"It’s the questions that drive us.”
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