A system-specific interface module for a motor control subassembly for controlling operation of an electric motor within a larger system which uses a particular system communication method. The motor control subassembly includes a standard power module and the interface module. The power module includes a controller processor configured to receive input for controlling and to generate output regarding operation of the motor. The interface module includes a communication interface hardware block configured to exchange input and output signals with the larger system, and an interface processor configured to translate the input and output signals between the particular system communication method used by the larger system and a standard internal communication method used by the power module. Thus, the motor control subassembly can be configured to accommodate any of a variety of different system communication methods and other input/output options by selecting and inserting the appropriate interface module.