Abstract: This paper addresses the problems existing in the control system of the current rubber mixing production line and the needs of enterprise informatization development. It introduces a network-based system transformation of the traditional rubber mixing production line using a self-developed intelligent control system. The transformation comprehensively considers several key factors such as transformation cost, system real-time performance, reliability, scalability, online prediction of production quality, and online fault diagnosis, thereby improving the system's intelligence and openness. Keywords: rubber mixing production line, control network, intelligent control Abstract: This paper introduces a self-development intelligent control system based on an industrial network for a mixing line. This system is used to upgrade an old system to meet the requirements of information technology development and address existing problems. Many important factors are considered in the new system, such as reconstruction cost, real-time performance, reliability, scalability, online quality prediction, and online fault diagnosis. The performance in terms of intelligence and operation is improved compared to the old system. Key words: mixing line, control network, intelligent control Introduction In recent years, with the rapid development of the tire industry, tire companies have been demanding the transformation of traditional production lines based on information technology to improve overall efficiency and decision-making reliability. However, they also need to avoid excessive one-time investment that could burden and risk the company. Therefore, upgrading production lines with network information technology based on existing equipment has become an urgent task. Rubber mixing is a crucial step in tire production. The operational quality of the rubber mixing production line directly impacts tire quality, cost, and efficiency. To meet the requirements of high quality, low cost, and high efficiency in rubber mixing production, improving the operating and monitoring environment, achieving remote real-time tracking and process optimization, enhancing the production management level of the internal mixer, and strengthening the networking of the underlying information system of the rubber mixing production line are of paramount importance. 1 Problems and Requirements [align=center] Figure 1 Rubber Mixing Production Line Flow[/align] A rubber mixing production line generally consists of three main parts: upper auxiliary equipment (including weighing and feeding systems for rubber, powder, and oil), rubber mixing equipment (internal mixer), and lower auxiliary equipment (rubber sheet extrusion, cooling, and weighing systems) (as shown in Figure 1). In traditional production lines, the control systems for these three parts are basically independent, and the control is relatively simple, resulting in severe information silos. The system struggles to achieve process optimization and adjustment, online monitoring of the production process, and online fault diagnosis and early warning. Furthermore, the rubber mixing production environment is extremely harsh: high ambient temperature, numerous high-power equipment, severe dust and noise, short mixing cycles (generally 2-5 minutes), and relatively dispersed equipment distribution on the production line. To fundamentally change this situation, it is necessary to organically integrate the three parts, strengthen the information exchange between the production line subsystems, and conduct research on intelligent data fusion, which is the key to the transformation of the rubber mixing production line. In view of the characteristics of the rubber mixing production line and the problems existing in the traditional system, the following characteristics should be considered when constructing the underlying information exchange network: (1) Ensure the real-time and reliability of information exchange in an environment where interference and exchanged data coexist; (2) The transformation process needs to retain most of the existing old equipment, but the communication capabilities and communication methods of electrical equipment from different manufacturers and at different times are uneven; (3) The system has fault self-diagnosis and early warning functions to ensure the reliability of exchanged data and the security of the physical system; (4) In order to track the quality of rubber materials online, online prediction of rubber material quality is required; (5) In order to improve the overall performance of the system, it is necessary to increase the information exchange capability between subsystems; (6) It is necessary to consider the future scalability of the system, especially the information exchange with the management level. 2 System Hardware Architecture 2.1 Determination of System Communication Methods Currently, the basic technologies for information exchange in industrial production mainly include serial communication based on general serial ports (such as RS-232C communication, RS-422/485 communication), fieldbus communication, and industrial Ethernet. Although industrial Ethernet is very attractive, due to the high cost of small information transmission, the limited number of supporting devices, and the fact that time determinism and repeatability have not been fundamentally resolved [1], the first two are currently the main types in the underlying information exchange network. RS-422/485 uses a balanced differential circuit, which can realize multi-point communication, and has strong anti-interference ability, long communication distance, and high communication speed, so it is widely used in industrial data communication [2]. Fieldbus technology is an industrial IT basic technology that has been developed in the last 20 years. It is a bidirectional, serial, multi-node digital communication system based on the OSI reference model [3]. Intelligent devices connected to the bus share the channel to exchange data and information. Currently, fieldbus has almost become synonymous with industrial data communication and control networks [1]. Profibus fieldbus is a fieldbus technology with multiple protocols coexisting. Data of different protocols are transparently transmitted within the system [4]. It is a comprehensive solution that can truly realize manufacturing automation, process automation, building automation, and power automation among many fieldbuses. It supports more and more devices and has good expansion capabilities. In the network-based control system transformation of the rubber mixing production line, we selected Profibus-DP as the main skeleton of the underlying control network. At the same time, considering the amount of communication data, cost, and other factors, some devices adopted the serial communication method based on RS-485. 2.2 System hardware architecture The signals that the rubber mixing production line needs to process mainly include: digital input signals (such as equipment status signals, manual control signals, etc.), digital output signals (such as equipment operation switch control signals, etc.), analog input signals (such as internal mixer rubber temperature, system hydraulic pressure, top bolt pressure, powder weight, oil weight, rubber weight, motor speed, main motor power, etc.), and analog output signals (such as top bolt pressure, motor speed, etc.). The instruments generally required in the production site include: multiple weight display instruments, multiple temperature display instruments, pressure display instruments, power display instruments, ammeters, etc. Most of these instruments have some digital communication capabilities, using communication methods such as RS-422/485 and Profibus-DP. In the design of the underlying control system for the rubber mixing production line, the Siemens S7-300 is used as the main controller, with an industrial control computer (IPC) as the monitoring station, and connected to the management layer via Ethernet. The field control layer uses Profibus-DP as the link to connect the main intelligent instruments and intelligent devices in the field. A small number of devices use RS-485 serial communication due to limitations in communication capabilities or considerations of modification costs, enhancing the intuitive understanding and interactive functions of production information for personnel at each workstation. The master PLC is responsible for exchanging information with the upper-level monitoring IPC, and also communicates with other intelligent devices (including two other PLCs) via Profibus. Each S7-300 controller is relatively independent, processing digital and analog signals from its respective subsystem. Meanwhile, due to the complexity of the rubber mixing process, it is currently difficult to achieve unmanned automation. Since the production line is generally distributed across four floors, to improve efficiency and reduce unnecessary malfunctions, two LED displays (communicationd via RS-485) and one monitor (or touchscreen) are added to facilitate different on-site personnel's understanding and interaction with production information, and to allow direct communication with the IPC. See Figure 2 for details. [align=center] Figure 2 Underlying Hardware Architecture of Rubber Mixing Production Line[/align] 3. System Software Architecture The network-based underlying network system architecture discussed above forms the foundation of this study. The intelligent implementation of the system is another major task of this study, including fault diagnosis, online prediction of key quality indicators, user-friendly human-computer interaction, and robust database management, process management, and interfaces with the management layer. Therefore, it is necessary to establish prediction models and fault diagnosis models based on Mooney viscosity and other key indicators reflecting the quality of the mixed rubber. The specific framework of the software system is shown in Figure 3. [align=center]Figure 3 System Software Architecture Diagram[/align] The entire application software system within the IPC is independently developed. This software system enables the IPC to manage production line process recipes, issue production plans to the underlying control system, perform online monitoring, manage the production process database, conduct data analysis, display and interact with remote field information (on touchscreens), perform process optimization modeling and online prediction of production quality, conduct online accident diagnosis and early warning, and exchange information with management. The IPC communicates with the PLC master station via an MPI interface through a CP5611 card. The entire IPC system software was developed using Delphi 7.0 in a Windows XP environment, and the database is managed using SQL Server 2000. 4 System Functions and Features By applying this system to transform the traditional rubber mixing production line, the overall performance of the rubber mixing production line control system has been improved: (1) It has a rich multi-point monitoring screen and can perform remote interaction (for example, production plans can be issued in the central control room or on-site); (2) It has increased the collection of necessary information, greatly enhanced the information exchange and coordination capabilities between subsystems, improved the overall system's operating efficiency and safety reliability, and effectively reduced the production risks caused by information "isolation" in the system; (3) The auxiliary equipment system (i.e., the rubber, powder and oil weighing system) has realized manual and automatic weighing, and the formula modification is convenient and flexible; (4) In addition to manual and ordinary automatic control, the mixing system can perform quality-centered intelligent control, predict the quality through the established Mooney viscosity online prediction model, and then control the mixing process; (5) By tracking the communication network, equipment operating status, process control status and main process data in real time, the system's fault diagnosis and early warning can be achieved; (6) It has the ability to exchange information with management, breaking away from the information silos of traditional systems; (7) At the same time, the system has strong database management and process formula editing capabilities. 5 Conclusion In the process of industrialization driven by informatization in traditional industries, the application research on networking of tire rubber mixing production lines with harsh environments and relatively complex production provides a practical and effective solution in terms of the construction of software and hardware systems. It also comprehensively considers the urgent needs of current industrial production and technological development, such as online quality prediction, online diagnosis and early warning of system faults, remote interaction, and interfaces with management. Compared with traditional systems, the intelligence and openness of the system have been greatly improved, providing a reference for the informatization transformation of other traditional production lines. References: [1] Feng Jianping. Fieldbus and Industrial Ethernet. Modern Manufacturing, 2001(10): 20-24 [2] Yang Xianhui. Industrial Data Communication and Control Network. Beijing: Tsinghua University Press, 2003 [3] Yang Xianhui. Fieldbus Technology and Its Application. Beijing: Tsinghua University Press, 2002 [4] Zhao Guangshe et al. Design of Modern Water Plant Production Network Control System Based on Fieldbus Technology. Computer Measurement and Control, 2002(3): 177-179 [5] Liao Changchu. 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