The Practical Instrument Electronics (PIE) Model 511 simulates RTD resistances into all types of instruments such as transmitters, recorders, controllers, alarms, data acquisition, and computer systems. The Model 511 is a superior replacement for decade boxes, so there is no need to lug a decade box around or be prone to error by reading RTD tables incorrectly. The PIE 511 has better accuracy and functions of many higher priced RTD calibrators.