These are questions I have been taught to ask in determining the type of data acquisition system that is needed.
a) What information is going to be extracted?
b) What processes or function are going to be used?
a) How many channels and are they simultaneous?
a) what is available?
b) what needed?
a) Low a few per second.
b) Medium 10 - 100 per second.
c) High > 1000 per second.
a) size and weight.
b) Environment factor.
a) Operating Cost
b) Reliability