Board Versus Box: The Age-Old DAQ Dilemma

Since the beginning of PC-based data acquisition and control in the 1980s, one question has remained a constant consideration for all who would specify a new DAQ system. Is this application better served by an external I/O "box" connected to the PC via some communications link, or an internal "board" system plugged into a slot within the computer? If anything, this question has become more complicated as technology has progressed.