The scope of this Supplement includes signal conditioning, signal multiplexing, analog-to-digital signal conversion, and data processing. This Supplement addresses stand alone data acquisition systems, typified by a sensor with an integral digital display, data acquisition systems that link multiple sensors to a common digital processor tied to a computer or printer, and systems that link multiple digital processors to one or more stand-alone or networked computers. This Supplement incorporates instrumentation practices covered by other Instruments and Apparatus Supplements (PTC 19 Series) as well as the equipment Performance Test Codes. It also provides a means to determine the uncertainty associated with the data acquisition system, and its impact on the overall uncertainty of the performance test. The Supplement does not directly address sensors or instruments used for ASME Performance Testing. These are addressed in other ASME Performance Test Codes.