First, smart home wired (bus) technology
1. Fieldbus
Fieldbus is the result of a combination of modern control technology, computer technology and communication technology. Fieldbus technology is a new thing that has flourished in the past ten years. It shows its strong vitality in practical engineering applications. The control network will develop along the field bus. Fieldbus technology will also be the core of control network technology. Each field control unit has the capability of digital processing and two-way high-speed communication, decentralized control, large network scale and high quality stability.
There are currently more than 200 fieldbus standards in the world, and there are many bus technologies for buildings, most of which are solutions for a specific application. At present, the representative fieldbus technologies and products in the world include FF bus, PROFI bus, LON bus, BACnet, CAN bus, INTER bus and CCLink bus.
The home control bus based on twisted pair, the communication medium mainly has CEBUS consumer electronic bus, LonWorks bus, APBus bus, RS-485 bus, EIB electrical installation bus. As far as the bus itself is concerned, the topology of these buses is basically the same.
RS-485 bus
The network characteristics use differential voltage transmission; generally use bus-type network structure, the number of bus nodes is limited, when using standard 485 transceiver, the maximum number of nodes in a single channel is 32, the transmission distance is close (about 1.2km), the transmission rate Low (300 ~ 9.6 kbps); poor transmission reliability, low cost for a single node, easy to design, easy to implement, low maintenance costs.
Strictly speaking, it is not a complete bus technology standard, only defined as the communication standard of the physical layer and the link layer. Many manufacturers use their technology to completely define their own bus technology standards, and the more representative American Honeywell C-Bus bus technology. In addition, more applications based on RS-485 technology are the MODBus standard.
CEBus bus
CEBus (ConsumerElectronicsBus) is a communication and product and operational standard developed by the Electronic Industries Association (EIA) for consumer electronics. It is the five types of media used for communication between home appliances (power line, wireless frequency, infrared). Transmission standard for signals in twisted pair and coaxial cable. The signal transmission rate and system capacity are 10 kbps and 4G, respectively.
APBus bus
The APBus bus is currently the only bus technology with China's independent intellectual property rights. It is a family-oriented, fully distributed intelligent control network technology similar to LonWorks technology. The product has two-way communication capabilities as well as interoperability and interchangeability, and its control components can be programmed. The signal transmission rate and system capacity are the same as CEBus, which are 10kbps and 4G respectively.
CAN bus
CANA (ControllerAreaNetwork), a peer-to-peer fieldbus network that supports distributed control and real-time control. Its network characteristics use differential voltage transmission; the number of bus nodes is limited. When using standard CAN transceivers, the maximum number of nodes in a single channel is 110, its transmission rate ranges from 5 kbps to 1 Mbps, and the transmission medium can be twisted pair and fiber. Etc., the transmission distance between any two nodes can reach 10km.
For a single node, the circuit cost is higher than RS-485. The design requires a certain technical foundation; the transmission reliability is high, the fault node is defined very conveniently, and the maintenance cost is low. Among several existing fieldbus methods, there is a high performance-price ratio.
LonWorks bus
According to the ISO/OSI7 layer model standard, a three-layer network structure is adopted: domain, subnet and node; using 48-bit ID neuron chip, the number of nodes is not limited, the transmission distance is far (about 2.7km), and the transmission rate is fast (300~ 1.25 Mbps); high transmission reliability, high cost for a single node, difficult design, high maintenance costs.
The development and application of LONWORKS technology in China's intelligent building industry started in the mid-1990s. It is basically synchronized with the development and application of this technology by large foreign companies. It has initially formed a product series suitable for China's national conditions. . For example, the Taiwanese Nico (NICO) LonWorks system, which uses a touch glass panel, is beautiful.
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