Philips Applied Technologies has developed the RT-Motion USB platform as a compact distributed real-time motion control platform, but the platform can still be improved by developing a more advanced software framework. The goal of this thesis project is to design a modular software framework to complement the RT-Motion USB platform with extendability, flexibility, and configurability. The design focuses on the extendability of the platform by developing foundation building blocks to integrate software extension modules and device drivers easily. The design emphasizes the principle of simplicity to ensure the lowest possible overhead and highest reliability. The firmware is modular, which allows each module to concentrate on its own area. The implementation of the design has been tested and is proved to provide extendability, flexibility, and configurability while incurring low overhead. The improvement to the RT-Motion USB platform is expected to extend the applicability of the RT-Motion USB platform to a broader application range.