Abstract: In the case of a data transmission system for the exchange of digital data between a central processor unit and several peripheral control modules which are connected to the former by a bus system such that communication is enabled and which are provided for the purpose of activating one each, respectively, out of several safety devices such as airbags or belt tensioning systems, or similar devices, in a motor vehicle, and wherein these peripheral control modules are each provided with one buffer capacitor whose energy content is sufficient for operating the respective module, and the device driven by this module, within specifications over a limited period of time, the bus system is designed as a single wire system for the purpose of achieving a simple setup and reducing installation and fitting costs. In this single wire system the control modules are supplied with electrical operating energy, and digital data are transmintted, by the same line sections.