Abstract: This article introduces the screen design and communication method between the host computer and PLC during the renovation of the nitrogen pressure station of Taiyuan Iron & Steel Group's cold-rolled silicon steel plant. Abstract: This paper introduces the monitor design and communication between the operation station and PLC during the reconstruction of the nitrogen pressure station in the cold silicon steel plant of TISCO. Keywords : WINCC, Ethernet Communication 1. Overview The main equipment of the nitrogen pressure station in the cold-rolled silicon steel plant of TISCO, consisting of two nitrogen compressors, originally used an S5-100U PLC control system. Both the S5-100U and the nitrogen pressure regulating instrument control system used on the old production line were put into operation in 1996. In 2006, a new nitrogen pressure regulating instrument control system was added for the new production line. After pressure regulation, nitrogen at various pressure levels is supplied to the No. 1 annealing line, No. 2 annealing line, normalizing and pickling line, and the 2300 electric furnace. Currently, due to a lack of spare parts and outdated control methods, it is necessary to integrate and upgrade the S5-100U PLC control system of the nitrogen compressors and the old and new nitrogen pressure regulating instrument control systems to better meet the needs of safe silicon steel production. 2. Screen Design The screen is designed using Siemens WinCC software, prioritizing user-friendliness, aesthetics, security, and practicality. The form is divided into three areas: a title area, a screen area, and a button area. The title area displays the screen name, the Taiyuan Iron & Steel Group logo, date, and time. The screen area displays each screen and the current alarm information; clicking the "Mute" button silences the alarm sound. The button area displays buttons for entering each screen and an exit button. There are five screens in total: the main screen, the data display screen, the interlocking condition screen, the curve screen, and the fault alarm screen. Clicking each button enters the corresponding screen. Clicking the "Exit" button pops up a small screen; only after entering the correct password can the "OK" button be activated. Clicking "OK" exits the WinCC program. 1) Main screen (as shown in Figure 1): Real-time display of the start and stop status of compressor #1 and compressor #2, green when starting and red when stopping; real-time display of nitrogen tank inlet pressure, outlet pressure, old line main nitrogen flow rate, cumulative flow rate, new line main nitrogen flow rate, cumulative flow rate, old line high-pressure nitrogen pressure regulating valve opening (PT106), old line low-pressure nitrogen pressure regulating valve opening (PT107), supplementary old line nitrogen pipeline pressure regulating valve opening (PCV108), supplementary new line nitrogen pipeline pressure regulating valve opening (PV205), new line high-pressure nitrogen pressure regulating valve opening (PT203), new line low-pressure nitrogen pressure regulating valve opening (PT201), and real-time display of various electromagnetic... The valve's on/off status is indicated by a green indicator when open and a red indicator when closed. Clicking on any regulating valve will bring up a small screen asking if you are sure you want to operate the valve. Clicking "OK" will take you to the valve's operation interface, where you can select "manual" or "automatic" adjustment mode. After operation, close the operation screen, then click "Cancel" on the small screen, and then click "Close" again to completely exit the operation for that valve. Similarly, there is an operation for resetting the cumulative nitrogen flow in the new and old main pipelines. Clicking on the flow valve will bring up a small screen. First, click the "Login" button, enter your username and password, and then click the "Reset" button for it to work; otherwise, resetting will not be possible. After the operation is complete, click the "Finish" button and then close the screen to completely exit the operation. [align=center]Figure 1: Main Screen[/align] 2) Data Display Screen (as shown in Figure 2): Real-time display of various analog values: #1 compressor current, #2 compressor current, circulating water pipeline water pressure, replenishing old line nitrogen network pressure, old line high-pressure nitrogen supply pressure, old line low-pressure nitrogen supply pressure, old line nitrogen network flow rate, new line nitrogen network flow rate, new line high-pressure nitrogen supply pressure, new line low-pressure nitrogen supply pressure, replenishing new line nitrogen network pressure, nitrogen compressor inlet nitrogen pressure, nitrogen compressor outlet nitrogen pressure, new spherical tank outlet nitrogen pressure, old spherical tank outlet nitrogen pressure, nitrogen oxygen content, circulating water main pipeline temperature, nitrogen compressor inlet nitrogen main pipe temperature, nitrogen compressor outlet nitrogen main pipe temperature; [align=center]Figure 2: Data Display Screen[/align] 3) Interlock Condition Screen (Figure 3): The interlock condition screen displays the start-up interlock conditions for nitrogen compressors #1 and #2, including low nitrogen compressor oil pressure, low cooling water flow, nitrogen compressor over-temperature level I and II, low nitrogen compressor inlet pressure, nitrogen compressor overflow, high nitrogen compressor oil temperature, and low oil temperature. Green indicates normal operation, and red indicates abnormal operation. [align=center] Figure 3: Interlock Condition Screen[/align] 4) Curve Screen (Figure 4): Includes four screens, displaying real-time curves for pressure, flow, and temperature. [align=center] Figure 4: Curve Screen[/align] 5) Fault Alarm Screen: Displays alarm faults in real time. After the alarm is cleared, it can be cleared by clicking the "Confirm" button. 3. Communication Method 3.1 Computer Control System Hardware Composition The computer part of the nitrogen compressor station computer control system consists of one Siemens S7-300 PLC and two WINCC workstations. The host computer uses a CP1613 communication network card. The nitrogen pressure station and the instrument control room of the No. 1 annealing line communicate remotely via fiber optic cable using a Siemens X204 switch via Ethernet through the CP343-1. See the diagram below. 3.2 Ethernet Communication Protocol: The host computer communicates with the S7-300 using the TCP/IP protocol. In WinCC, the S7 communication channel is selected, a new connection is created in TCP/IP, and the system parameters—unit—are set to TCP/IP—DLink DFE—530T1; the IP address attribute is set to the PLC's address. (As shown in Figures 5 and 6) [align=center] Figure 5: System Parameter Settings Figure 6: Attribute Settings[/align] 3.3 Characteristics of Ethernet Communication Ethernet technology has been introduced into the industrial control field, and its technical advantages are very obvious: 1) Ethernet is a fully open and fully digital network. Devices from different manufacturers can easily interconnect according to network protocols; 2) Low hardware and software costs. Since Ethernet technology is very mature, hardware and software supporting Ethernet are highly valued and widely supported by manufacturers, with various software development environments and hardware devices available for users to choose from; 3) High communication speed. As the scale and complexity of enterprise information systems increase, the demand for information is also increasing, sometimes even requiring the transmission of audio and video data. Currently, 10M and 100M Fast Ethernet are widely used, Gigabit Ethernet technology is gradually maturing, and 10G Ethernet is under research. Its speed is much faster than the current fieldbus. 4. Conclusion This system has been put into normal operation and is running stably. Local and remote station personnel can monitor the parameters and faults of various instruments in real time through the screen and solve problems in a timely manner.