Rapid prototyping is a well recognized need in the design and development phases of advanced systems for automation. In particular, this concept is also important for the design and experimentation of control algorithms and new mechanical prototypes in advanced robotics. Moreover, flexibility, short development times and contained economical costs are other important features considered in developing new industrial applications and, of course, new robotic and control system experimental setups. Recently, the growth in performances of low-cost PC-based architectures and the diffusion of free-distributed software packages has given the possibility of developing rapid prototyping tools taking into account all these needs. In this work, we present the real-time control system of an industrial manipulator, the Comau SMART 3-S, developed under RTAI-Linux, a real-time variant of Linux. The main goal was to build a flexible and highly configurable robotic setup to quickly test new control algorithms and to easily (and safely) use the robot in different manipulation tasks.