Abstract: A sensor is disclosed which exchanges with associated data acquisition equipment a digital attribute signal, distinct from its transducer output signal, on the occurrence of a predetermined event. The invention is particularly illustrated with reference to an accelerometer which transmits sensor identification data to associated data acquisition equipment when power is first applied by using the same two signal lines as are used to provide power to the sensor and to convey the sensor output signal to the equipment. After the identification data is transmitted, the apparatus operates as a buffer amplifier to modulate the transducer output signal onto the same two signal lines.