The DJW(L) series horizontal (vertical) magnetron sputtering coating production line manufactured by Zhaoqing Dali Vacuum Equipment Co., Ltd. uses DC or medium-frequency power to control planar targets, cylindrical rotating targets, or medium-frequency twin targets to sputter films onto workpieces. It is widely used in various industries such as architectural glass, ITO transparent conductive glass, appliance glass, high-reflectivity rearview mirrors, and acrylic coating. This series of production lines absorbs advanced technology and coating processes from similar European production lines while incorporating a unique, user-friendly, and easy-to-use design concept, which has been highly praised by users. In this series of magnetron sputtering coating production lines, a 10.4-inch Pro-Face color touchscreen has become the standard configuration as the main operating interface, and its operation is relatively stable. Because there are many process parameters that need to be controlled in the coating production process, in order to further improve work efficiency and the controllability of the coating process, we have designed a computer monitoring system to monitor and optimize the entire production process, thereby making the coating production process highly repeatable and more suitable for the needs of large-scale industrial production. 1. Functional Design of the Monitoring System Based on the working conditions and production requirements of the production line, the computer monitoring system is designed with the following functions. (1) Mode Selection: In order to meet the working needs of the production line, the computer monitoring system is designed with two operating modes: an automatic monitoring mode for coating production and a manual monitoring mode for debugging and maintenance. The two operating modes can be switched freely. (2) Process Scheme Selection: In order to realize the automation of coating for various workpieces, the monitoring system is designed with a variety of process schemes for users to choose from. Before the equipment is running, the user can select the scheme to be used or set a new scheme, and then start coating production. (3) Data Detection and Recording: In order to facilitate users to monitor the process, analyze and study the role of process parameters, and adjust process parameters in a timely manner to obtain better coating effects, the monitoring system: 1) displays the power supply voltage, current, vacuum count value, gas flow rate and other parameter values ​​of each magnetron target in real time; 2) records the equipment operation status at regular intervals, once every 30 minutes, or as required at any time; 3) records important process parameters and forms report files and historical curves. (4) Fault alarm record: 1) When the equipment malfunctions, the monitoring system automatically pops up an alarm screen and text prompt, and the alarm light flashes at the same time; 2) Record all alarm information for reference during maintenance; 3) According to the severity of the fault, the alarm information can be classified. (5) Automatic diagnosis and protection: This is a protection measure to reduce the damage to the equipment caused by the fault. It is mainly manifested in: 1) When the equipment has a serious fault, the monitoring system can automatically shut down; 2) After the magnetic power supply is turned on, its voltage and current are slowly increased and decreased to protect the power supply; 3) It can automatically detect whether the communication between the upper and lower computers is normal. (6) Operation permission restriction: This function can be used to restrict the permissions of general users to prevent misoperation and reduce the probability of error; at the same time, it can also realize the unification of control and monitoring. (7) Other functions: The computer monitoring system also has some practical functions such as system clock, equipment input and output point monitoring interface, and equipment operation instruction interface to facilitate user query and use. 2 Composition of the monitoring system The computer monitoring system consists of three parts: upper computer, lower computer and communication protocol. The system hardware structure is shown in Figure 1. The host computer is used to monitor production operation status and process data, complete the overall control of coating production, and use the acquired historical data as a basis for coating effect detection and analysis. Because the environment in which the host computer operates is relatively free of interference, a common PC is selected, with the Microsoft Windows XP operating system being widely applicable and feature-rich. The monitoring and data acquisition software used is the INSPEC E20 general-purpose configuration monitoring system software developed by Beijing Jiusiyi Automation Software Co., Ltd. It is the world's first product of its kind based on Microsoft's latest operating platform, .NET, and boasts a series of advantages such as powerful monitoring functions, stable performance, beautiful graphics, ease of learning and use, high development efficiency, and easy expansion. It uses the high-level language C# as the user program (scripting) language, which can well meet the control requirements. The data acquisition and display functions are also relatively complete. Once the device drivers are installed, it can communicate with various PLCs, intelligent instruments, boards, and frequency converters, and can also be connected to other computers to form a distributed production management network for the enterprise. The INSPEC universal configuration monitoring system software is used to develop automated control screens. The host computer screen allows for real-time monitoring of the coating production process, and important data is saved to files. When production abnormalities occur, audible alarms and text prompts are issued for exceeding limits or malfunctions, and relevant screens pop up for operators to quickly analyze and handle the situation, enabling production to resume in the shortest possible time. The slave computer consists of a Mitsubishi PLC and various modules, including: one FX2N-128MR main unit, one FX2N-16EYR output expansion module, four FX2N-4DA analog output modules, two FX2N-4AD analog input modules, and one FX2N-232-BD communication board. The INSPEC universal configuration monitoring system supports OPC servers and can connect to third-party software. Since the Mitsubishi PLC has a dedicated communication driver, data exchange between the host and slave computers is achieved via a shielded RS-232 serial cable. The host computer and the slave computer communicate via a question-and-answer mechanism. The host computer sends communication commands (downlink commands) to the slave computer, and upon receiving a response command (uplink command) from the slave computer, the host computer continues to send downlink commands. Based on the requirements of the monitoring system, the communication protocol uses a periodic command sending method, and data transmission employs an event-driven communication approach. For received data, the communication protocol performs frame length verification, character verification, and timeout verification before sending it to the host computer. If an error is found during verification, a retransmission mechanism is applied to retransmit the erroneous frame until it is correctly received. All control operations are performed by the slave computer; the host computer is only responsible for providing the human-machine interface, receiving and sending commands, controlling automated processes, displaying and storing data, setting parameters, printing reports, and processing data. During system operation, the host computer continuously communicates with the slave computer in real time, ensuring that the data displayed on the interface matches the actual data; operation commands and parameters set by the operator on the host computer are also sent to the slave computer for execution in real time. Because it is equipped with a touch screen as a redundant operating device, the production line can be switched from the computer monitoring system to the touch screen operation mode at any time without affecting production, facilitating equipment maintenance and improving system reliability. 3. System Process Flow Design and Control Process Implementation Based on the process requirements of the magnetron sputtering coating production line, the coating production control can be designed into four time-sharing processes. The first process is vacuum acquisition; to ensure coating quality, the system must have a certain basic vacuum. The second process is ion bombardment; to improve film adhesion, high-energy ion bombardment is used to clean the workpiece surface to remove surface impurities and dirt. The third process is magnetron sputtering coating; electrons emitted from the cathode are subjected to Lorentz force in the magnetic and electric fields, and propel themselves along the direction of the magnetic field in a cycloidal motion, depositing onto the workpiece surface to form a thin film. The fourth process is system start-up and shutdown; this involves the processing operations of the entire equipment before and after coating. 3.1 Automated Control Design of Vacuum Acquisition Process The vacuum system of the magnetron sputtering coating production line uses a slide valve vacuum pump-Roots vacuum pump-high vacuum oil diffusion pump unit to obtain low and high vacuum. A microcomputer-based digital display vacuum gauge is used to detect the vacuum level. The automated control of this process includes: ① start-stop control of mechanical pumps, diffusion pumps, vacuum gauges, and water pumps; ② high and low vacuum value output control of each vacuum gauge; ③ opening and closing control of each vacuum valve and flap valve. The entire set of equipment uses circulating water treatment for cooling, so the vacuum unit cannot be started before the system receives a water pressure indication. The flap valve is used to isolate the atmosphere from the low vacuum chamber and the low vacuum chamber from the high vacuum chamber; the vacuum valve is used to control the opening and closing of the vacuum pumping passage. The system controls the opening and closing of the valves through pneumatic devices. 3.2 Automated Control Design of Ion Bombardment Process For some models (such as acrylic coating production lines), in order to improve the adhesion of the thin film, this system uses high-energy ion bombardment as a pre-plating treatment process. During the bombardment cleaning process, the control parameters include argon mass flow rate, bombardment voltage, bombardment current, bombardment time, and transmission speed. To meet the requirements of the coating process, the workpiece can be allowed to pass slowly through the bombardment chamber while being bombarded, or it can be allowed to remain in the bombardment chamber for a period of time before entering the buffer chamber, thus achieving high-energy ion cleaning of the workpiece. 3.3 Design of the Automated Control System for the Coating Process To meet the requirements of the coating process, it is necessary to control parameters such as argon mass flow rate, reactant gas mass flow rate, sputtering voltage of each target, sputtering current, and coating transmission speed. When the workpiece reaches the magnetron target, the target current automatically switches from the maintenance state to the working state to coat the workpiece until it leaves the target, at which point it returns to the maintenance state, maximizing the conservation of target material. To effectively protect the magnetron target and target power supply, the system is designed with water pressure and vacuum control, overcurrent and overheat fault alarm functions, and a gradual increase/decrease function for the target power supply voltage and current. 3.4 Automated Control Design for System Start-up and Shutdown Automatic startup begins with the diffusion pump preheating, followed by automatic operation of the vacuum pumping system until the coating chamber vacuum is reached, at which point the magnetron target automatically starts. All operations during this process are completed automatically by the equipment. Automatic shutdown occurs after the coating process is completed, automatically shutting down the magnetron target and gradually closing the vacuum pumping system. All operations during this process are also completed automatically by the equipment. 4 Algorithm Control 4.1 Feedback Algorithm During system application, there is always a certain error between the setpoint and displayed value of the magnetron power supply. To unify the two, we designed a feedback algorithm using software for power supply data setting and display, which has proven very effective. Let the current power supply displayed data (collected data) be X_n, and after time T, the displayed data be X_n+1. The initial power supply setpoint is S₁, and the corrected setpoint is S₂. The specific calculation process is shown in Figure 2. In the flowchart, d, k, and e are selected constants. |X_n+1-X_n|Δ = k〔S₁-（X_n+1+X_n）/2〕 is the feedback quantity to be obtained. 4.2 Range Conversion Algorithm The range conversion of the entire monitoring system is divided into two parts and three stages. Part 1: Data Display: 1) Power range converted to 0-10V output 2) 0-10V output converted to 0-2000 integer input to the computer 3) 0-2000 integer converted back to power range for display Part 2: Data Setting 1) Power range converted to 0-500 integer output to the computer 2) 0-500 integer converted to 0-10V input power supply 3) 0-10V input converted back to power range for setting Each stage of conversion is a linear simulation process. Only the conversion slope needs to be calculated to obtain the corresponding conversion value. For example, when converting a 0-10V output to a 0-2000 integer, the conversion slope K = 2000/10 = 200. Therefore, for any input X, the conversion value Y = KX = 200X. 5 Conclusion The computer monitoring system for the magnetron sputtering coating production line introduced in this paper has been running smoothly and reliably. The display is realistic and expressive, providing good monitoring results and enhancing the user's system image. As a successful computer monitoring system for coating production lines, we plan to adapt it for use on various coating equipment. Therefore, it has great promotional value and application prospects, thereby promoting the development of computer monitoring technology for vacuum coating equipment in my country.