1 Introduction The high-speed wire rod production line of Anyang Iron and Steel Company was approved by the Henan Provincial Economic and Trade Commission in 1999 and put into operation in August 2001. This high-level wire rod production line has a high level of equipment and automation, reaching the international level of the late 1990s. It introduced the latest wire rod rolling mill from the United States in the late 1990s, adopted an 8+4 finishing mill and sizing mill scheme, and used a high-quality and efficient walking beam heating furnace. The entire line is controlled by cooling and rolling. In order to obtain high-yield, high-quality and low-consumption wire rod coils, the rolling mill adopted a complete set of advanced automated control systems. The entire production process and operation monitoring are controlled by computers. Its main control features are: (1) fast networked communication; (2) fast system response speed; (3) high dynamic and static accuracy of transmission equipment; (4) accurate tracking and positioning of rolled pieces; (5) high reliability of software programming, etc. 2. Main process parameters of Angang high-speed wire rod (1) The main process parameters of Angang high-speed wire rod are as follows: • Output: Designed annual output of 450,000 tons; • Billet: or; • Product: φ5.5-20mm ordinary wire coil or Rbφ6.0-16mm threaded wire coil; • Varieties: Low carbon steel, medium carbon steel, high carbon steel, welding rod steel, spring steel, bearing steel, low alloy steel, cold heading steel, etc.; • Coil weight: • Rolling speed: Guaranteed speed of 112m/s and maximum operating speed of 120m/s (2) The main mechanical equipment, starting from the outlet side of the heating furnace, includes: heat-insulating roller conveyor, No. 1 pinch roll, 6-stand alternating horizontal and vertical roughing mill, No. 1 flying shear, 8-stand alternating horizontal and vertical intermediate mill, No. 2 flying shear, 2-stand double-module pre-finishing mill, No. 1 water cooling box, No. 2 pinch roll, No. 3 flying shear and cutting shear, 8-stand V-type non-twist finishing mill, No. 2 and No. 3 water cooling boxes, 4-stand V-type reducing and sizing mill, No. 4 and No. 5 water cooling boxes, No. 3 pinch roll, and wire drawing machine. (3) The main auxiliary production equipment of the rolling line includes 7 hydraulic systems and 3 thin oil lubrication systems, which are located in 3 oil depots and 7 hydraulic stations. The hydraulic and lubrication systems are powered by the rolling line MCC control center. The main detection elements of the rolling line consist of 11 DELTA DC3000 hot metal detectors, 8 LAND high temperature gauges, 6 DELTA TS2006 looper scanners, as well as encoders, proximity switches, phototubes, etc. 3. Automated Rolling Mill Scheme The overall technical scheme of this fully continuous high-speed wire rod mill automation and speed control transmission system is based on high-performance industrial microcomputers, programmable logic controllers (PLCs) and fully digital AC and DC drive control systems, forming a fully distributed network and a modern control system with advanced 20th-century level. The entire automation system consists of a two-level control system, a three-layer communication network, and fully digital DC and AC drive speed controllers. 3.1 Two-level Control System The two-level control system consists of a human-machine interface (HMI), a server, a basic automation system and a speed control transmission control system, which respectively complete different control functions. (1) Human-machine interface (HMI) The human-machine interface (HMI) consists of 6 high-performance microcomputers, which mainly realize the human-machine interface functions of the automation system, including: input, storage and modification of rolling tables, setting of rolling parameters, dynamic display of the status and electrical parameters of each equipment during rolling and manual adjustment of process parameters, general operation and display of electrical equipment, fault alarm and recording, generation, storage and printing of documents and reports, etc. (2) Server The entire automation system consists of three servers: OS-SEVER (operator station server), ES-SEVER (programming server), and PCS-SEVER (process control server). They are connected to the PLC via an industrial IoT network and independently complete their respective functions. (3) Basic Automation The basic automation system uses Siemens' latest S7-400 series PLC products, and the remote I/O station uses ET200M. The basic automation system is completed by five PLCs to complete all automation control functions (excluding furnace combustion control and water cooling section control). The five PLCs control the following respectively: ·ENTRY PLC: All equipment from the hot conveyor roller to the furnace outlet roller. ·CMIL1 PLC: All equipment from the front pinch roll of No. 1 roughing mill to the wire drawing machine, mainly completing the sequence control of the rolling line and the control of the flying shear. ·CMIL2 PLC: All equipment from the front pinch roll of No. 1 roughing mill to the wire drawing machine, mainly completing the roll changing control of the rolling mill and the positioning control of the wire drawing machine. ·MODPLC: All equipment from the Stemmore air-cooled line to the unloading station (excluding trimming, bundling and card-making machines) ·MEDIAPLC: All hydraulic and lubrication systems. ·Speed ​​transmission control system The electrical drive adopts the latest fully digital speed control system from Siemens. DC drive adopts SIMREG DC-MASTER 6RA70 series fully digital speed control device, AC drive adopts 6SE70 vector control frequency conversion speed control device, and finishing mill and sizing mill adopt 6SE80 IGBT medium voltage frequency conversion speed control device. 3.2 Three-layer network automation system The communication network is divided into three layers: (1) The first layer is connected between the human-machine interface and the server, between PLCs, and between PLCs and the server to realize a large amount of information exchange between them. Through the state network, the rolling process parameter setting value and the operation of electrical equipment are transmitted from the human-machine interface to the PLC, and the status, process, electrical parameters and faults of each equipment are collected by the PLC and sent to the CRT display of the human-machine interface. That is, the state network mainly performs data communication with a large amount of information transmission. (2) The CPUs of each PLC in the second layer are connected to form an MPI network to realize a small amount of fast information exchange between CPUs. (3) The PLCs in the third layer use a PRFIBUS-DP communication network to communicate with their respective remote I/O stations and speed control drives. The PLCs transmit the set parameters and control commands to each speed control drive system and collect the status and electrical parameters of the drive system and send them to the CRT of the human-machine interface for display. 3.3 Features of the Automation System (1) Features of the three-layer network The configuration diagram of the Angang high-speed wire rod automation system is shown in Figure 1. a) Ethernet A bus-type local network that uses the TCP/IP protocol. It can connect each PLC and workstation to exchange information. Its main features are as follows: • Data transmission rate: up to 10Mbps • Number of workstations on the network: up to 1024 • Transmission medium: optical fiber • Topology: bus • Information protocol: variable frame size, 64 to 1518 bytes. The performance of this network falls between that of a remote network and a multiprocessor network. It is mainly used for office automation, distributed data processing, terminal access, and other high-speed, bursty information exchange systems. b) MPI Network: The MPI network is a multi-point interface communication network. Its communication port is integrated on the CPU, allowing simultaneous connection to a programmer and a PC (e.g., HMI). Networked CPUs can use Global Data Service (GD) to periodically exchange data (16 GD packets are allowed per program cycle, each packet up to 64 bytes). The CPU's MPI is directly connected to the S7's K bus. Figure 1. Configuration diagram of Angang High-Speed ​​Wire Rod Automation System. Basic data for MPI are as follows: • Data transmission rate: 187.5Kbps; • Number of workstations on the network: Maximum 32; • Transmission medium: Twisted-pair shielded cable; • Transmission distance: 50m without repeaters; 9100m with 10 repeaters; 1100m with 2 repeaters. c) Profibus Network. Profibus is a real-time, open industrial fieldbus network. Its characteristics include: digital transmission, easy correct reception and error verification, ensuring data reliability and accuracy, reducing cable connection costs between lower-level equipment in the factory, easy installation, maintenance and expansion, and timely fault detection for early handling. Its greatest advantage is its ability to fully utilize the capabilities of intelligent devices. The communication protocol of the Profibus network card conforms to Parts 1-3 of the European standard DIN19245, namely the Profibus-DP protocol. This standard allows high-speed cyclic communication of small amounts of data, thus the bus cyclic scan time is extremely small, less than 2ms in specific environments. The basic data of the Profibus network is as follows: · Data transmission rate: 1.5Mbps; · Number of workstations on the network: up to 32; · Transmission medium: twisted pair shielded cable; · Data transmission method: master-slave token method. (2) Software features a) CFC graphical configuration · SIMADYN D software “D7-SYS”; · STEP (SIMATIC manage HW configuration). b) CFC graphical configuration software · Standard minimum top-level function · Each function block has 5 selectable sampling times, and the control program can be selected according to the running speed requirements to achieve timely control · Flexible function package construction · Can be named arbitrarily in the configuration · Easy to connect with peripheral devices · Hardware can be selected and defined · Can be set, modified and supplemented online (the previous graphical configuration software could not modify the structure and configuration online). (3) Speed ​​regulation transmission features The fully digital control system has good performance and high reliability, and can meet the requirements of high dynamic quality and high speed regulation accuracy. The fully digital device also provides comprehensive monitoring, protection, and fault self-diagnosis functions for the drive system. It also features convenient and fast communication networking, allowing it to communicate with automation systems for parameter setting and information exchange. The medium-voltage frequency converter control system is a TRANSVEKTOR controller, which can also select frequency, speed, and torque control. Vector control with a pulse generator ensures high performance during normal rolling: a speed range greater than 1:10. Speed ​​adjustment accuracy: approximately 0.1% without encoder feedback, and approximately 0.002% with encoder feedback. 4. Conclusion Angang High-Speed ​​Wire Rod Electrical Automation widely adopts AC frequency conversion technology and DC digital speed control technology in its transmission system. High-power AC motors also utilize medium-voltage IGBT frequency conversion technology. In terms of control, it employs the PCS7 distributed control system, a three-layer network, and two-level control. It also promotes the application of PRFIBUS-DP fieldbus technology, industrial Ethernet token ring network technology, and server-client technology. The user software utilizes CFC and SFC programming technologies, as well as T300 process board positioning control technology. The application of these technologies has enabled the automated assembly of the entire line to reach a first-class level domestically and an advanced level internationally, with all economic and technical indicators reaching leading levels in China. These technologies can be widely applied to various sectors of China's national economy, and are particularly suitable for applications in the metallurgical industry such as bar, wire rod, and plate mills, which involve impact loads and high-speed continuous rolling.