The paper presents a real-time open software simulation framework, dedicated to the analysis of control systems deployed over distributed execution resources and wireless links. It is able to consistently simulate in parallel the numerical devices (real-time tasks and communication links) and the evolution of the controlled continuous time plant. It is applied to foresee future enhancements of a Functional Electrical Stimulation (FES) system used in therapy for rehabilitation or substitution for disabled people. It is a distributed control system using electrodes to interface a digital control system with livings. Hence the whole system gathers continuous-time (muscles and nerves) and discrete-time (controllers and wireless links) components. During the design process, realistic simulation remains a precious tool ahead of real experiments to check without danger that the implementation matches the functional and safety requirements. The simulation tool is especially devoted to the joint design and analysis of control loops and real-time features.