An apparatus includes multiple circuit paths configured to generate multiple electrical signals to be used to communicate with multiple devices. Each of the circuit paths is configured to use electrical energy from a different one of multiple independent power supplies. The apparatus also includes an I/O terminal configured to be coupled to a common electrical conductor that is coupled to the multiple devices. The I/O terminal is configured to pass the electrical signals to the common electrical conductor. The apparatus is configured to use each of the electrical signals to one of: receive input data from one of the multiple devices or provide output data to one of the multiple devices.