Abstract: A motor controller that incorporates all of the advantages of RS-485, yet allows the user to interface with the controller through RS-232 without a separate RS-232 to RS-485 converter. The controller includes a port for receiving RS-232 compatible signals. The RS-232 signals are converted to RS-485 compatible signals which are, in turn, converted into logic level signals suitable for the motor controller. The RS-485 signals may be shared among a number of controllers, and an RS-485 port is provided for such a purpose. RS-485 ports can be interconnected via a common bus so that a number of motors can be separately controlled from a master controller (usually a personal computer) that is connected to any available RS-232 port.