Wiring for the MediaSensor™ P51 integral harness is depicted on this slide. Transmitters with a 4-20mA output signal are 2 wire, loop powered devices. Red is power and white is return (signal). Transducers with the voltage output are 3 wire devices, with red being power, white being Vout, and black going to ground. Note the wiring for gauge units displayed has a vent tube while the absolute or sealed gage unit does not.