Abstract: The invention relates to a method for the testing of the error-free function of modules in a bus system with a central unit as well as suitable modules, a corresponding central unit and a corresponding bus system. For this purpose, an especially agreed-upon silence-command is provided, in response to which the modules in the error-free condition switch into a silent operating mode, and also expressly transmit no data particularly in response to the data requests allocated to the modules. By means of this silence-command, at first all modules can be set into the silent operating mode, and then by means of the agreed data request it can be tested whether all modules still switch into the silent operating mode. A module that nonetheless still transmits is recognized as faulty and is, for example, deactivated.