Hello Tam,
The three things you can do to prevent a buffer overflow from occurring are to decrease the sampling rate, increase the buffer size, or increase the number of samples per channel to read. It sounds like you have already tried increasing the buffer size, and instead of solving the problem, has just delayed the buffer overwrite. I would then try to both decrease the sampling rate of your acquisition, and increase the number of samples per channel you read each iteration. If you decrease the sampling rate of your acquisition, data will enter the buffer at a slower rate, and LabVIEW will be able to better keep up with emptying data from the buffer. You can also try increasing the number of samples per channel to read, so that LabVIEW empties more samples from the buffer each iteration. You could try setting the 'number of samples per channel' of the DAQmx Read VI to -1, which will tell LabVIEW to empty all available data in the buffer during each iteration. Give these suggestions a try and let us know how it turns out. Also, here's a helpful document that explains how to monitor the number of samples remaining in the buffer at all times.
KB 2ZFHCKL1: (DAQmx) Error -200279 During a Continuous, Buffered Acquisition
Regards,
Travis G.
Applications Engineering
