voltage read 1d 2d simulataneously

[Dick Hing]

Hi everyone,

I need to read both time and amplitude and store the data in excel (for 8 channels simultaneously). The DAQmx read (Analog 1D wfm N channel N sample) allows me to get the time duration, time array etc. But for the y-axis, I seemed to get a single amplitude point from the waveform using WDT Get Y value.vi. To get all samples (eg, 240 samples), I would need to use a for-loop. But I understand that the loop will slow down the system.

On the Analog 2D dbl N channel N sample, it allows me to grab all amplitude data in 1 go. So, is there a way for me to run both analog read 1D and 2D at the same time for all 8 channels?

Thanks in advance for your help!

Regards,

Dick Hing

[devchander]

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The DAQmx read (Analog 1D wfm N channel N sample) allows me to get the time duration, time array etc.

But for the y-axis, I seemed to get a single amplitude point from the waveform using WDT Get Y value.vi. To get all samples (eg, 240 samples), I would need to use a for-loop. But I understand that the loop will slow down the system.

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You will have following 3 components in a waveform data set: start time(t0), interval between data points( dt) and data values of waveforms (y array)

Use 'Get waveform components' function to seperate out these three components

You have your set of amplitude points y array (axis), ready

Find Y array's size.

Now using 't0', Y aray size and dt  build your time array( x axis).

Or use 'Get waveform time array' function to get your x array

you can index out the waveform dataset of each channel and perform this operation

And finally, if your acquisition is continuous, you cannot use both the DAqmx Read instances ( 1D and 2D) at the same time

Hope this helps

Dev

Message Edited by devchander on 09-19-2006 03:47 AM

Message Edited by devchander on 09-19-2006 03:48 AM

Message Edited by devchander on 09-19-2006 03:50 AM

[Dick Hing]

Thanks for the quick reply! I will definitely try it out.

No, I'm using finite sampling.

Thanks again.