Hey,
Questions regarding Hardware = Hardware Forums
Out of your other post's it seems that you are talking about DAQmx, so the Help gives a pretty good answer to your question:
How is Buffer Size Determined? (Output Tasks)
For generations, the amount of data you write before starting a generation determines the size of the buffer. The first call to a Multiple Samples version of the Write function/VI creates a buffer and determines its size.
You also can use the Output Buffer Config function/VI to create an output buffer. If you use this function/VI, you must use it before writing any data.
The samples per channel attribute/property on the Timing function/VI does not determine the buffer size for output. Instead it is the total number of samples to generate. If n is your buffer size, setting samples per channel to 3×n generates the data in the buffer exactly three times. To generate the data exactly once, set samples per channel to n.
NI-DAQmx does not create a buffer when the sample mode on the Timing function/VI is set to hardware-timed single point.
Christian
