A method and corresponding devices for transmitting data between a central control device of a passenger protection system in a vehicle and at least one local sensor unit. The sensor unit includes a sensor and is operated in a normal operation mode or in a test operation mode. In the normal operation mode, the data transmitted contain sensor measuring data while in the test operation mode, they contain characteristic data. The sensor unit transmits its data packets in both modes of operation after a synchronization pulse that was last detected and adds to the data packets a different characteristic depending on the operation mode by adding at least one data bit so that the data packets of the normal operation mode and of the test operation mode can be uniquely identified using the respective characteristic.