Robot motion controllers consist of a very important component in a robotic infrastructure. The flexibility is more and more needed to allow fastness in development and adaptation from one robot to another. The laboratory of robotic systems of the Ecole Polytechnique Fédérale de Lausanne (LSRO-EPFL) has initiated the work presented in this paper to propose a PC based architecture that is both flexible and open. This paper presents this architecture, how it can be open for a use with any robot structure even in industry or for laboratories. We will stress on its safety and flexibility to add more components. The flexibility of this control has been proven with the different applications that run based on the same control kernel. With easiness and fastness different field buses have been implemented (Firewire, profibus and now USB).