Building automation is based on a control network that uses protocols and application software and consists of three levels: the field level with the sensors and actuators, the automation level where data communication with the components of different levels takes place, and the management level.
The automation level is located above the field level. The control units located on this level, the Direct Digital Controls (DDC), communicate with the sensors and actuators connected to the fieldbus and with the components on the management level.
Wired fieldbus systems include the European Installation Bus( EIB), CAN bus, LON bus, BACnet, BatiBUS, M-Bus, the European Home Systems( EHS), the Konnex bus ( KNX) and Powerline. In addition, radio-based systems such as ZigBee or WLAN are also increasingly being used.