Interchangeability – the basis is that the devices are not certified, but their communication. The controller chip is mostly uniform. What is made of it is manufacturer-specific. There are standardized protocols (over 100 so-called network variables) but much more manufacturer-specific. This means that an adjustment and the so-called binding must always proceeded. The devices are configured for network by using a software tool. The functioning of the BUS system depends on right engineering. In this respect, integrators are specially trained and certified. These additional costs can only be covered if the projects are of a certain size.