The EIB System for Home & Building Electronics
The European Installation Bus (EIB) is an open, comprehensive system, which covers all aspects of Building Automation. This protocol is similar with the BACnet protocol and is manage by EIB Association.
The European Installation Bus (EIB) is designed as a management system in the field of electrical installation for load switching, environmental control and security, for different types of buildings.
Its purpose is to ensure the monitoring and control of functions and processes such as lighting, window blinds, heating, ventilation, air-conditioning, load management, signaling, monitoring and alarms.
The EIB system allows the bus devices to draw their power supply from the communication medium, like Twisted Pair or Powerline (230 V mains). Other devices may, additionally, require power supply from the mains or other sources, as in the Radio Frequency and Infrared media.
Figure 1. EIB network protocol that link together domotic elements
Network Topology. Main Features of the Bus
The Installation Bus is designed to provide distributed technical control for management and surveillance of buildings. Therefore it provides a serial data transmission between the devices connected to the bus. It also operates as a compatible, flexible low-cost system supporting the above applications.
EIB is a protocol that manages devices placed into a complex bus. This bus can be divided in different trees that fit on the structure of buildings and houses. The maximum number of devices that could be connected is 65’536.
The Bus system is usually implemented as a decentralized system but nevertheless it still allows, whenever it is required, centralized application implementations. Decentralized management is implemented within the devices whether they are transmitters or receivers, they communicate directly to each other without recourse to hierarchy or network supervisory device. This type of management makes the system highly flexible.
Figure 2. Centralized system
Figure 3. Decentralized system
The application nevertheless allows for a centralized management mode. An Application Controller (ApC) may be positioned on anywhere on the bus.
EIB Medium Access Control (MAC) is highly optimized for each medium individually. Available implementations further optimize for a combination of transceiver performance and cost. EIB.IR (Infrared), EIB.MMS (MultiMedia Services), EIB.TP (Twisted Pair), EIB.PL(Powerline), EIB.RF (Radio Frequency), EIB.net (Automation Networking)
EIB Bus devices are generally built up from two parts: the Bus Coupling Unit and the application module that manage processes in the building automation. The Bus Coupling Unit is a decentralized bus manager in each device and provides electrical features as well as data coupling to the Bus, in order to allow the separation of application hardware and software from the Bus communication system. The application module manages the process in building or house.
The gateway represents the bridges between different segments of one or more networks. These gateways realize two roles. The first consist in the connection of the two segments of networks sometimes routing the telegrams and the second consist in the adaptation of protocols that manage the data transfer in the whole system.
An Installation Bus System may be connected via gateways to external networks. This connection may be done either at the backbone, the main line itself or the any other line. Examples for such gateways are:
- Data over voice
- Analog phone connection
- ISDN connection
- Field bus connection
- Connection to mainframe computer
The information exchange between two devices is achieved by transmission of data packets. Each data packet must be acknowledged. For every medium, the message frame looks similar like the figure bellow.
AnFigure 4. EIB Message frame
Some media will precede or follow this message by some medium specific sequences, characteristic for its medium access control or error correction mechanisms.
Figure 5. Structure of an EIB compliant telegram
The data packet (see figure above) contains the following fields:
- Control field
- Source address field
- Destination address field
- Length
- LSDU (Link Service Data Unit) - info to be transferred-
- Check byte
In the case, for example, of failure detection message or any other urgent message, the EIB system allows a transmission priority to be assigned to the transmission of the data packets.
Alarm messages may have priority over all other messages sent in normal operation mode. Retransmitted data packets have also higher priority than normal packets.
An important role in the standard EIB is play by the mapping of devices through the network, which will be detailed in the next paragraph.
Mapping of building / home devices interconnected by the EIB network
EIB Bus devices connected to the Installation Bus can be addressed using two modes:
- Physical addressing
- Group addressing
The mapping of devices represents an application of the devices included in the network on a part of natural numbers. Every bus device is identified by a unique physical address. Two EIB Bus devices should not have the same physical address.
The physical address (see figure 5.5) consists of a zone, line and EIB Bus device number; it corresponds to the device as a whole. The source address field always contains the physical address. The physical address is only used as destination address for initialization, programming and diagnostic operations (connection oriented transmission). This corresponds to a system access mode.
Figure 6. Address structure for source and destination of telegram (system accessing mode)
Figure 7. Connectivity between different elements using system-accessing mode through EIB
Group addressing corresponds to the normal operation mode. Functions of EIB Bus devices belonging to the same group may be controlled by only one message sent by a "source" EIB Bus device. Functions however, may belong to several groups and may be activated independently by every EIB Bus device of the group.
Figure 8. Address structure for source and destination of telegram (group accessing mode)
The group addressing is a logical link between bus devices. A sensor can only transmit on one group address and an actuator can receive several. The group addressing gives flexibility by means it allows to add a bus device in a very simple way, just by connecting it to the correct group address.
Figure 9. Connectivity between different elements using group-accessing mode through EIB