Application and Realization of L-type Network Train Monitoring System
1 Introduction
With the continuous development of science and technology and the wide application in various industries, more and more evidence proves that the unification of technical standards in an industry or a wider field is becoming more and more important, and has become a restriction or promotion of industry technology development. An extremely important factor. The same problem exists in the railway system. If there is no unified standard, each vehicle system manufacturer often develops proprietary and incompatible interface products along its own path to restrict the buyer to only use their system. It is not conducive to product and technology competition, which restricts the development of related technologies. For quite a long time in the past, the train network communication technology of the railway system was in a state without standards, which greatly restricted the development of the train network monitoring system technology. In 1999, for the train communication network, two corresponding standards were formulated internationally: "Train Communication Network" developed by IEC (International Electrotechnical Commission) and "Train Network Communication Protocol" developed by IEEE (American Institute of Electrical and Electronics Engineers). The content of the latter includes the former, which specifies two types of train communication networks: T-type and L-type. The T type is the TCN network (train communication network), and the L type is the LonWorks communication network specified in the "Free Topology Twisted Pair Channel Specification". With reference to the above two international standards and the actual situation of domestic railway traction, in 2002, the Ministry of Railways of China also formulated the corresponding "People's Republic of China Railway Industry Standards-Train Communication Network". This standard also specifies two types of train communication networks: T-type and L-type. At present, the application of domestic train communication networks is mainly concentrated on L-shaped networks. The adoption of open IEEE standards in the railway system will ensure the interoperability of products from multiple manufacturers, which can help promote the competitiveness of every link in the supply chain and accelerate technological development.
2. Characteristics of network control technology
LonWorks (Local OperaTIng Networks) is a field bus technology launched by the American Echelon company in 1991. It can solve a large number of problems in the design, composition, installation and maintenance of control networks.
Features of LonWorks network control technology:
(1) Openness: Open network protocol, equal to any user;
(2) Interoperability: LonWorks communication protocol LonTalk conforms to the OSI open interconnection model defined by ISO (International Organization for Standardization). Any manufacturer's products can be interoperable;
(3) Communication media: almost all currently available communication media, including twisted pair, power lines, optical fibers, coaxial cables, radio waves, infrared rays, etc., and there can be multiple communication media in the same network;
(4) Network structure: it can be master-slave, peer-to-peer or client / server mode;
(5) Network topology: star, bus, ring and free-form;
(6) Communication rate: up to 1.25Mb / s, at this time the effective communication distance is 130m. In the case of twisted pair, the straight line communication distance is up to 2700m at 78Kb / s rate;
(7) LonWorks network communication adopts an object-oriented design method: LonWorks network communication technology is called "network variable", which simplifies the design of network communication into parameter settings and increases the reliability of communication;
It is precisely because LonWorks technology fully satisfies the requirements of future development for measurement and control systems. At present, its use has spread throughout the industrial, building, transportation, energy and other automation fields of 56 countries and regions in the world.
3. Application of LonWorks technology
3.1 The provisions of the Ministry of Railways' train communication network standard for L-type networks
The standard stipulates that “applicable to the connection of an electronic device within a basic operating unit (single vehicle or fixed combination of vehicles) or a group of basic operating units. ", Mainly used in train monitoring systems. Due to the relatively fixed composition of the monitoring objects of the train monitoring system and the particularity of the train formation, the standard also specifies the most commonly used network topology and bus relationships in the network, as shown in Figure 1.
Network structure and bus relationship
Control Transformer,Pure Copper Control Transformer,Remote Control Transformer,Micron Control Transformer
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