Programming is required in order to install KNX. A microprocessor assumes the coordination of all the functions. The application module and the application program define the functions of all bus devices. The respective application programs are loaded into the device with the project planning and commissioning software ETS 3 via the serial or USD interface of a PC. The planning software on the PC is used to specify the addresses of the KNX devices, the tasks, the command allocation and the logical connections.