how do I setup the example "Online Spectrogram Monitoring" with the DAQ?

[mikeeg555]

I have opened the DAQ example located in help for "TFA Online STFT Spectrogram VI: Online Spectrogram Monitoring (DAQmx) VI: labview\examples\Time Frequency Analysis\TFAFunctions.llb

I have adjusted the settings to reflect my setup:

Analog input voltage

DC coupling

Channel: cDAQ1Mod1/ai0

But, when I run the program, there is no signal. When I probe the signal line (1D array of waveform) in LabVIEW when it is running it also appears as an empty signal.

I know there is a signal present on the channel because I am simultaneously physically monitoring it on an oscilloscope. Also, when I use the Express VI "DAQ Assistant"and plot the signal from that, it shows up properly. This may mean that it is a problem with my set-up of the DAQmx Read.VI

Am I missing something simple?

Cheers!

[ManLongAtNI]

Do you have an appropriate module set for an AI Accelerometer task? An unsupported module will cause an error and will not run your program. Does your program run continuously as it was designed or does it stop?

Regards,

Glenn

[mikeeg555]

I've changed the accelerometer into a AI Voltage which I do have the module for. I am able to see my channels and select one that physically has a signal on it. I've changed the coupling to DC. These setting reflect my physical set up.

When I run it, it it does not return an error, but runs continuously.

On closer inspection, when the example is first loaded and run with these settings, a signal briefly appears, but is quickly offset upwards above 10.75V where it is clipped to a flat line, which looks like an absence of signal. My oscilloscope does not show any offset. (?)

Very odd

[ManLongAtNI]

What device are you using? Are you able to run a basic Analog Measurement task from one of the examples from the Example Finder? Is your issue isolated to the graph being unable to plot your DAQmx Read?

[mikeeg]

My device is a NI 9205 DAQ installed in the NI cDAQ-9172.

I have switched to using the DAQ Assistant express vi. For some reason I have no problems using this.

[ManLongAtNI]

The individual DAQmx vi's provide better control to your application, but in your case, The DAQ Assistant appears to have resolved your issue. If you decide to revert back to the original program, I recommend using highlight execution and probes to determine at what point in the process you are not getting the expected value. 

Regards,

Glenn