The Analogic AN2559 is the first, value-added, 3 3/4-digit, 3999-count DPI featuring builtin versatility and flexibility . It comprises a basic, universally powered digital panel instrument with standardized connectors into which an ever-expanding library of special- and general-purpose plug-in PC cards can be readily field-inserted and interchanged without any DPI modifications. Consequently, a single AN2559 can accomplish custom or standard analog input signal conditioning and digital output interfacing to fulfill a seemingly unlimited range, of commercial, industrial, and laboratory instrumentation applications. By stocking only the AN2559, most OEM users can satisfy all of the the 3 3/4-digit DPI requirements. Versatility in the AN2559 includes an internal power and signal interface connector that accepts a general-purpose plug-in card upon which the user can install proprietary analog-interface circuits, or Analogic can add special-purpose circuits during manufacture, whichever is more economical. Typical analog-interface functions that can be provided are: ac and dc current measurements, extended range ac and dc voltage measurements, active multiple filtering, optimized signal filtering, thermocouple or RTD temperature transducer conditioning, LVD T excitation and demodulation, frequency-to-voltage conversion, cur rent sourcing, auto-ranging, and very high impedance buffering. All with ±3999-count resolution. Power and space are provided in the AN2559 to accommodate an optional digital circuit card for such value-added features as isolated and/or buffered parallel BCD outputs, digital linearization, and set-point control. Again, these features can be incorporated by the user, or for OEM quantities, engineered and installed by Analogic. Since the basic AN2559 design is so widely flexible and adaptable, it decisively offers more value-added application possibilities than any competitive DPI.