An on-board automotive system comprising a plurality of processing units adapted to transmit data between said processing units via a common bus, where one or more of said processing units has a convertor unit associated therewith, said convertor unit being connected to a parallel bus of the processing unit from which data is transmitted, said parallel bus comprising a plurality of lines, and wherein said converter is adapted to convert data transmitted therefrom to one or more of said processing units in the form of a single serial data stream along said common bus.