LonWorks is a decentralized system consisting of numerous intelligent devices (sensors, actuators, and control elements) combined into a common network. Data exchange between all devices in the system takes place via LonTalk®, a dedicated open protocol (data exchange language).
A distinctive feature of LON (Local Operating Networks) is the absence of a central control device, a controller, which significantly improves the system's reliability, flexibility, and scalability.
The system is built from sensors and actuator modules that operate autonomously; all modules are connected to a common low-current bus over which information is exchanged and control commands are transmitted. With this approach, if one module fails, the other elements keep working.
Transmission media
The transmission media used in LonWorks technology are: twisted pair, 230 V power cables, coaxial cables, fiber-optic cables, radio transmitters, and infrared signal transmission systems.
Topology
LonWorks networks use various topological structures, namely: star, ring, line, tree, bus, and free topology. The entire network is divided into segments interconnected by routers.
The length of a single segment for transmitting control signals and data in LonWorks technology can exceed two kilometers. Moreover, using routers, repeaters, or gateways, the network structure can be expanded (scaled) to virtually unlimited size.
Data transmission
A single data network in a building or building complex based on LonWorks technology can include up to 32,000 intelligent devices (sensors, actuators, and control elements).
Depending on the network structure, the data transmission rate can reach 1.25 Mbit/s. Particularly important signals, such as fire alerts or signals from the security alarm system, are given top transmission priority on the network.
To guarantee delivery of an information signal, a special command delivery/receipt confirmation procedure is used.
If a site requires protection against unauthorized access to transmitted data, a unique data encryption system is applied.
Event logging
Alongside ensuring the security and reliability of the LON® system, special importance is also attached to logging all events occurring in the building management system, as well as the system's response to these events.
Events in the building management system are recorded with the exact time and their relationship to other events. In addition, all data output by the system is logged, such as emergency signals, warning messages, notifications, etc.
Standards
- European standard CENELEC EN 14908-1:2005.
- International standard ISO/IEC 14908.
- Chinese standard GB/Z 20177.1-2006.
- American standard ANSI/CEA-709.1-B.