Sensor technology, communication technology and computer technology are the three foundations of modern information technology. With the rapid development of IT technology and the continuous improvement of industrial automation requirements, the work undertaken by industrial control network is getting heavier and heavier. Different from the data information network, the industrial control field needs a high-speed, cheap, real-time, open, high-stability and accurate network. Ethernet technology supports almost all network protocols, so it is widely used in data information networks, with many advantages, such as fast transmission speed, low energy consumption, convenient installation, good compatibility, high openness, complete equipment and so on. The openness of industrial Ethernet makes the seamless integration of industrial control network and enterprise information network have unparalleled advantages.
I. Characteristics of Industrial Ethernet Technology
Ethernet technology has the advantages of low price, stability and reliability, high communication rate, rich software and hardware products, wide application and mature supporting technology, and has become one of the most popular communication networks. In recent years, with the development of network technology, Ethernet has entered the control field, forming a new type of Ethernet control network technology. This is mainly due to the development of industrial automation system to distributed and intelligent control, and an open and transparent communication protocol is an inevitable requirement. Ethernet technology has been introduced into the field of industrial control, and its technical advantages are very obvious:
(1) Ethernet is a completely open digital network, and devices from different manufacturers can be easily interconnected according to network protocols.
(2) Ethernet can realize seamless connection between industrial control network and enterprise information network, and form a fully open network with enterprise-level management and control integration.
(3) Low cost of software and hardware. Because Ethernet technology is very mature, the hardware and software supporting Ethernet are highly valued and widely supported by manufacturers, and there are many software development environments and hardware devices for users to choose from.
(4) High communication rate. With the expansion and complexity of enterprise information system, the demand for information is increasing, and sometimes even audio and video data need to be transmitted. At present, fast Ethernet with Ethernet communication rates of 10m and 100m has been widely used, and gigabit Ethernet technology has gradually matured. 65,438+00 G Ethernet is also under study, and its speed ratio.
(5) There is great potential for sustainable development. In this era of rapidly changing information, the survival and development of enterprises will largely depend on a fast and effective communication management network, and the development of information technology and communication technology will be faster and more mature, thus ensuring the continuous development of Ethernet technology.
Second, the application status of industrial Ethernet in the control field
Compared with field bus, industrial Ethernet can provide an open standard, which enables enterprises to realize comprehensive and seamless information integration from field control to management, and solve 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.
(A) Hybrid Ethernet/Fieldbus network structure
This structure is actually a typical integrated form of information network and control network. Ethernet is gradually developing to the field device level, and it is integrated with other network forms as much as possible. However, Ethernet and TCP/IP are not oriented to the control field, and are not mature in architecture, protocol rules, physical media, data, software, experimental environment and many other aspects. Fieldbus can completely meet the basic requirements of modern enterprises for the underlying control network and realize a truly fully distributed system. Therefore, the enterprise information layer adopts Ethernet and the bottom equipment layer adopts fieldbus, and the information exchange between them is realized through the communication controller.
(2) Special 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 Jetter AG in Germany, is an industrial automation control system integrating fieldbus technology, 100Mb/s Ethernet technology, numerical control technology, PLC technology, visual man-machine interface technology and global production management technology. At the same time, it has a wide range of compatibility and can be compatible with third-party automation control products. It puts forward the view that "the network is the controller", which is an industrial network structure that replaces all the underlying field buses. This industrial control network runs through all levels of the whole network through Ethernet, making it a transparent application entity covering the whole enterprise. It realizes the seamless combination of office automation and industrial automation, and is essentially a single-layer horizontal organization. Its good scalability and interconnection make it a truly unified fully open network architecture.
(C) Web-based network monitoring platform
Embedded Ethernet is a hot spot of network application in recent years, which enables all devices connected to the network, from computers, PDA, communication equipment to instruments and household appliances, to communicate with each other through the Internet. Within the enterprise, the enterprise information network can be used to publish and display the real-time operation data of the factory, and managers can conduct real-time remote monitoring, remote equipment debugging and remote equipment fault diagnosis and treatment through the Web browser. The simplest method is to connect the control host with TCP/IP interface and the field equipment with RS-232 or RS-485 interface with an independent Ethernet controller. Here, the Ethernet controller acts as a bridge between the general computer network and various field devices.
Third, the development trend of Ethernet switching technology
The rapid development of Ethernet and communication technology has promoted the further development of industrial Ethernet technology. At present, it has been widely used in resource management layer and executive manufacturing layer of integrated automation system of industrial enterprises, and it has a downward trend of direct application in industrial control field. From the development of industrial Ethernet technology at home and abroad, industrial Ethernet has been widely used in manufacturing executive layer and has become the de facto standard. In the future, industrial Ethernet will play an increasingly important role in the interconnection and information integration between field devices in the integrated automation system of industrial enterprises. Generally speaking, the development trend of industrial Ethernet technology will be reflected in the following aspects:
(A) the combination of industrial Ethernet and field bus
The research of industrial Ethernet technology has only attracted the attention of industrial control experts at home and abroad in recent years. After more than ten years' development, Fieldbus has become more and more mature in technology, and has begun to be fully popularized in the market, forming a certain market. At present, there are still some problems in completely replacing fieldbus. It is necessary to further study the new control system architecture based on industrial Ethernet and develop a series of products based on industrial Ethernet.
(2) The direct application of industrial Ethernet technology to the communication between industrial field devices has become the general trend.
With the improvement of Ethernet communication rate and the development of full-duplex communication and switching technology, it provides a technical basis for solving the certainty of Ethernet communication, thus eliminating the main obstacles for Ethernet to be directly applied to communication between industrial field devices and providing technical possibilities for Ethernet to be directly applied to communication between industrial field devices. Therefore, IEC of the International Electrotechnical Commission is drafting the Real-time Ethernet (RTE) standard to promote the comprehensive application of Ethernet technology in the industrial control field.
(C) Web-based network monitoring platform
Embedded Ethernet is a hot spot of network application in recent years, which enables all devices connected to the network, from computers, PDA, communication equipment to instruments and household appliances, to communicate with each other through the Internet. Within the enterprise, the enterprise information network can be used to publish and display the real-time operation data of the factory, and managers can conduct real-time remote monitoring, remote equipment debugging and remote equipment fault diagnosis and treatment through the Web browser. The simplest method is to connect the control host with TCP/IP interface and the field equipment with RS-232 or RS-485 interface with an independent Ethernet controller. Here, the Ethernet controller acts as a bridge between the general computer network and various field devices.
Third, the development trend of Ethernet switching technology
The rapid development of Ethernet and communication technology has promoted the further development of industrial Ethernet technology. At present, it has been widely used in resource management layer and executive manufacturing layer of integrated automation system of industrial enterprises, and it has a downward trend of direct application in industrial control field. From the development of industrial Ethernet technology at home and abroad, industrial Ethernet has been widely used in manufacturing executive layer and has become the de facto standard. In the future, industrial Ethernet will play an increasingly important role in the interconnection and information integration between field devices in the integrated automation system of industrial enterprises. Generally speaking, the development trend of industrial Ethernet technology will be reflected in the following aspects:
(A) the combination of industrial Ethernet and field bus
The research of industrial Ethernet technology has only attracted the attention of industrial control experts at home and abroad in recent years. After more than ten years' development, Fieldbus has become more and more mature in technology, and has begun to be fully popularized in the market, forming a certain market. At present, there are still some problems in completely replacing fieldbus. It is necessary to further study the new control system architecture based on industrial Ethernet and develop a series of products based on industrial Ethernet.
(2) The direct application of industrial Ethernet technology to the communication between industrial field devices has become the general trend.
With the improvement of Ethernet communication rate and the development of full-duplex communication and switching technology, it provides a technical basis for solving the certainty of Ethernet communication, thus eliminating the main obstacles for Ethernet to be directly applied to communication between industrial field devices and providing technical possibilities for Ethernet to be directly applied to communication between industrial field devices. Therefore, IEC of the International Electrotechnical Commission is drafting the Real-time Ethernet (RTE) standard to promote the comprehensive application of Ethernet technology in the industrial control field.