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The application and development prospect of Ethernet technology in the field of control

Ethernet is a local protocol that can be used for energy recovery (incineration) using carrier sense multiple access method with collision detection (CSMA/CD) to access shared media according to the provisions of IEEE802.3 standard, which corresponds to the physical layer and data link layer in the ISO/OSI seven layer reference model. The transmission medium of Ethernet is coaxial cable, twisted pair, optical fiber, etc., which adopts bus or star topology, and the transmission rate is 10 Mb/s, 100 MB/s, 1000 MB/s or higher. In the field of office and business, Ethernet is the most commonly used communication network. In recent years, with the rapid development of Ethernet technology, Ethernet technology has been widely used in the field of industrial control

1. Advantages and characteristics of Ethernet technology in the field of industrial control

in the field of industrial control, with the continuous increase of the scale of the control system, the geographical dispersion of the controlled object, measurement and control devices and other physical equipment is becoming more and more obvious, and the centralized control system can no longer meet the requirements. The distributed control system and the subsequent fieldbus control system are the technologies that conform to this trend and solve this problem to a certain extent. However, in 1999, the fieldbus technical standard iec-61158 was issued, and eight kinds of fieldbuses have become the fieldbus technical standards of IEC. Its essence is that there is no really unified communication standard. Therefore, the major industrial control manufacturers in the world are looking for other ways to solve the problem of scalability and compatibility, so Ethernet, which is widely used in information networks, has become the preferred target

Ethernet is the most popular and widely used communication technology today. It has the advantages of low price, a variety of transmission media can be selected, high speed is a kind of material that can achieve energy conservation in green buildings, and it is easy to group applications. Moreover, it has the most rich operating experience and has a large number of installation and maintenance personnel. It is an ideal industrial communication network. Its advantages and characteristics are mainly reflected in the following four aspects:

first, Ethernet based on TCP/IP is a standard open communication network, and devices from different manufacturers are easy to interconnect. This feature is very suitable for solving the problems of compatibility and interoperability of equipment from different manufacturers in the control system

second, low cost and easy assembly are the advantages of ether. The price of too laggy is low, and the interface between Ethernet and computers, servers and so on is very convenient. There are many Ethernet technicians, which can reduce the cost of enterprise training and maintenance

third, Ethernet has a fairly high data transmission rate, which can provide sufficient bandwidth. Moreover, the ability of sharing Ethernet resources is strong. Using Ethernet as the fieldbus, it is easy to connect I/O data to the information system, and the data is easy to share with the resources, application software and database on the information system in a real-time manner

IV. Ethernet is easy to connect with the Internet. In any city, anywhere, you can use the Internet to monitor and control the production of enterprises; In addition, Ethernet, as the most widely used computer network technology, has received extensive technical support. Almost all programming languages support the application development of ether, with a variety of development tools to choose from

v. great potential for sustainable development. Ethernet is the most widely used computer network at present. Its development has been widely valued and a lot of technical support. Industrial control network adopts Ethernet technology, which can avoid its development drifting away from the mainstream of computer network technology. In addition, industrial control network and information network technology are combined, promoted and developed together, which can ensure the sustainable development of technology and avoid the re investment in technology upgrading in the future

with the development of economy and the progress of automation technology, enterprise integrated automation and management and control integration have become the only way for enterprises to survive and develop. Ethernet is convenient to realize the seamless connection between office automation network and industrial control network, which can closely combine e-commerce with industrial production control and realize the integration of enterprise management and control

2. The application status of Ethernet technology in the control field

compared with fieldbus, industrial Ethernet can provide an open standard, which enables enterprises to realize comprehensive and seamless information integration from field control to management, and solves the problem of "automation island" caused by different protocols. However, from the current development, the application of industrial Ethernet in the control field is mainly reflected in the following forms:

I The network structure of hybrid ethernet/fieldbus is actually a typical integration form of information network and control network. Ethernet is gradually developing to the field device level and merging with other network forms as much as possible, but Taihe tcp/ip is not originally oriented to the control field and is not familiar with many aspects such as architecture, protocol rules, physical media, data, software, experimental environment, etc., while fieldbus can fully meet the basic requirements of modern enterprises for the underlying control network and realize a truly fully distributed system. Therefore, Ethernet is used in the enterprise information layer, and fieldbus is used in the bottom device level to realize the information exchange between the two through the communication controller

Second, dedicated industrial Ethernet control network

how to use industrial Ethernet as a control network alone is one of the development directions of industrial Ethernet and one of the research hotspots in the field of industrial control. For example, jetweb, a new generation control system of German jetter AG, is an industrial automation control system integrating fieldbus technology, 100mb/s Ethernet technology, CNC technology, PLC technology, visual human-machine interface technology and global production management technology. At the same time, it has wide compatibility and can be compatible with third-party automation control products. It puts forward the view that "network is controller", It is an industrial network structure that replaces all the underlying fieldbus. This industrial control network is a transparent application entity covering the whole enterprise by penetrating ether into all levels of the network. It realizes the seamless combination of office automation and industrial automation. In essence, it is a single-layer flat structure. Its good scalability and interconnection make it a real unity of fully open network architecture

third, the web-based network monitoring platform

embedded Ethernet is the recent hotspot of network application, which is to make all devices connected to the network interoperate with each other through the Internet, from computers, PDAs, communication devices to instruments, household appliances, etc. Within the enterprise, the enterprise information network can be used to publish and display the real-time operation data of the factory. The manager can carry out real-time remote monitoring, remote equipment debugging and remote equipment fault diagnosis and processing of the on-site working conditions through the web browser. The simplest way to realize is to use an independent Ethernet controller to connect the control host with tcp/ip interface and the field equipment with RS-232 or RS-485 interface. The Ethernet controller acts as a bridge between the general computer network and various field devices

3. The development prospect of Ethernet technology in the control field

there are two kinds of application structures of Ethernet in the industrial field, namely, the control center network structure and the device center network structure. In the network structure of the control center, industrial Ethernet is combined with fieldbus. Ethernet is applied in the upper layer of the enterprise to connect the controller, operator station and management computer. The lowest layer of the enterprise is the fieldbus structure, which is the solution of integrating the control network and the Internet. In the device central network structure, I/O devices are connected to Ethernet. In this structure, Ethernet replaces fieldbus, and industrial Ethernet technology is directly applied to the communication between industrial field devices, truly establishing a unified Ethernet structure from the upper layer to the lower layer of the enterprise

people in the industry are more and more aware of the importance of Ethernet in the field of industrial control. It is suggested that the blast furnace should be replaced according to the ratio of 1:1.25 to tighten the production capacity. Ethernet has become the main direction of the development of control system network and has great development potential. Of course, industrial Ethernet has some limitations, such as bus power supply, intrinsic safety, and the absence of a unified application layer protocol. With the gradual solution of these problems, the continuous acceleration of Ethernet speed, and the continuous improvement of communication certainty, reliability, and real-time, industrial Ethernet will have a broader application and development prospects. (end)

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