40 Digital Switch Input Transmitter (DSIT40) 40 Digital Switch Input Transmitter (DSIT40) 40 Digital Switch Input Transmitter (DSIT40) 40 Digital Switch Input Transmitter (DSIT40) The Digital Switch Input Transducer has been designed to provide an isolated output depending upon the digital inputs to the device and the operating mode selected. Originally designed as a transformer tap position transducer.