Hi mooktank,
Please see the first paragraph of my previous post.
When the acquisition is taking place, hardware is automatically putting data into the "DAQmx Buffer". When you call DAQmx Read, data is pulled out of the DAQmx Buffer. While you can set the buffer size to be higher, if your DAQmx Read cannot read data as quickly as it is being put into the buffer over the long-term, you will eventually receive error -200279.
When performing buffered acquisitions at even moderate speeds, you will want to read multiple samples per loop iteration so your software can keep up. I usually shoot for a loop rate of around 10 Hz or so if I'm just monitoring and logging data--this would mean that the Number of Samples to Read should be equal to Sample Rate / 10. Every situation is a bit different, but 10 Hz should be a good starting point if you're not trying to implement any sort of feedback control.
Best Regards,
John Passiak
