It is often the case when acquiring data that you do not need to "see" or "process" each data point as it comes in, i.e. to respond in one sample time. For example, if you are acquiring analog data at 1 kHz, you certainly don't need to display the data for viewing "as it comes in", as the eye cannot "see" changes that fast. In these situations, it makes sense to take, say, 1000 samples at 1 kHz, which means that once a second, you get (and can process) the "latest data".
Why is this helpful? Recall that LabVIEW is a Data Flow language, which means that you can have separate loops doing separate processing events at the same time. So your DAQ loop can be waiting for the next set of 1000 points to come it, while a Display-and-logging Loop can use that second to display the previous second's worth of data and log it to disk. If, on the other hand, you tried to take single samples, every millisecond you'd be trying to update the Display and write to disk, and would likely fall behind as you'd probably be doing everything in the same loop.
Note that if a second is too long to wait to see the "latest data", you could take only 20 samples at a time, and update your display at 1000/20 = 50 Hz, about the speed that the eye can process changing visual data.
Bob Schor
