a serial interface circuit electrically connected to a controller to control an electric motor . the interface circuit includes a controller circuit and a motor circuit . the controller circuit includes a transmitter and a receiver circuit , and the motor circuit includes a transmitter circuit and a receiver circuit . the interface interrogates the motor to acquire status and diagnostic information by receiving commands from the controller , adjusts a voltage level to a desired level , outputs the voltage signal to command and control the motor , and receives a voltage response from the motor .