Clock synchronization of distributed computers in building automation networks using an AC power supply

With the implementation of extended functions in building automation networks more and more of these functions require a synchronization of the clocks within their computers with a central reference clock. Therefore synchronization methods are needed which are accurate enough and very cost effective. In this paper a new method for the clock synchronization is proposed which fulfills these requirements. In this method a rough synchronization is performed with communication telegrams and a refining of the synchronization is realized with the zero-crossings of the voltage at a common AC power supply.