I am using a NI 6120 multifunction DAQ with LabView 7.0 to acquire 3 analog signals. Specifically, I'm using the AI C-Scan VI. My understanding is that I must sample all three channels at the same rate, and I would like for this rate to be the maximum of 800 kS/s for the purpose of computing a PSD plot. Also, I want to acquire a decent size chunk of data at a time so that the frequency resolution on the PSD plot is relatively high across the 400 kHz span. Finally, the three acquisitions need to be synchronized so that they can be compared in the time domain. The problem I'm having is that, for all three channels, I can't read the data fast enough to keep the buffer from overflowing. Even if I get the acquisition to last for a little while by using a huge buffer, scans appear to be dropped, as seen in the concatenated waveforms which are discontinuous. What is the best way to handle this problem? Should I be using something other than the AI C-Scan? If it helps, the PSD's can be calculated after the acquisition process rather than real time.
