RoboSim, a simulation environment designed to control modular robots with C code which can be used without modification for hardware robot control, is presented within this paper. The increasing presence of computer simulations to initially validate code designed for hardware robots is confirming their benefits as a method to quickly and easily prototype software design. RoboSim is integrated within the Ch programming environment, a C/C++ interpreter that provides the capability to remotely control robots through code, which allows switching between hardware control and virtual robots without modifying said code. Open source software projects Open Dynamics Engine, OpenSceneGraph, and GTK+ are employed to provide the virtual environment and user interface which afford the capability of running on different software platforms. Experiments were conducted which validated the accuracy of the virtual robots through comparison of results to the hardware robots.