Multiple analog output at different rates (using 6733)

[Carson Chen]

Hi,

I am using a PCI-6733 card, and would like to to generate the waveforms to drive a X-Y scanner.

Channel X: sawtooth, 512 points, 500 KHz

Channel Y: sawtooth, 512 points, 1 KHz

I searched the forum and the only way I found is to set the clock rate at the highest clock (500 KHz).

In that case, I will need 512 x 500 data points for channel Y.

As the data points needed exceeds the on-board buffer, the error message pops up and the program stops to generate waveforms.  

Would you please recommend a good solution for this application? Thanks in advance.

Best,

Carson

[Brooks_C]

Hi Carson,

The short answer is that once you have generated the 512 x 500 points for your slower saw tooth waveform you need to also generate that many points for the channel X waveform (you will generate a waveform that really contains 500 periods of the faster wave).  Once you have these two waveforms you can use a DAQmx Timing VI and set the buffer size to the correct value.  In your case you need to have a buffer of 512 x 500 = 256,000 samples/channel.  I think that this was probably the answer you were looking for, but just incase you were asking about another step I went ahead and generated an example program that should take you through the entire process of generating the waveform data with the correct update frequency and resolution and then using the buffer to output the data.

I hope this helps and please reply back if you have any further questions.