BINARY SENSOR WITH DIAGNOSTIC SIGNAL SUPERIMPOSED ON BINARY OUTPUT

A binary sensor has a device for detecting the presence or condition of an object. The sensor has circuitry connected to the detecting device to generate a binary output signal that represents the presence or condition of the object. The sensor also includes circuitry that generates a diagnostic signal associated with the sensor. The diagnostic signal is superimposed on the binary output signal. The binary output signal with the superimposed diagnostic signal are simultaneously transmitted to a controller such as a Programmable Logic Controller or a smart drop in a bus network. The diagnostic signal is designed so that it will not interfere with the ability of the controller to recognize the binary output. The controller may be provided with circuitry to detect and interpret the diagnostic signal.