To improve the production process execution rate of rubber processing plants, strengthen process management, facilitate on-site inspection of process parameters, and promote the implementation of Enterprise Computer Integrated Manufacturing System (CIMS), Enterprise Management Information System (MIS), and ISO 9000-9002 quality standards, we designed a distributed computer measurement and control system for the rubber processing process based on a CAN bus for a rubber processing plant. The entire computer measurement and control system consists of 4 engineering workstations and 13 field control stations. The system uses Windows 9x as the operating platform and a CAN bus network structure. The entire system has been running stably for a year and is performing well. Rubber processing plants generally have sections for compounding agent weighing, mixing, vulcanization, and repair, with weighing and vulcanization being the two most critical sections. Currently, in some rubber processing plants in my country, weighing, batching, and vulcanization are manually operated and controlled, and human factors greatly affect the processing quality and vulcanization performance of rubber products. To reduce the impact of human factors, it is essential to adopt computer control for batching, weighing, and rubber vulcanization processes. The entire computer control process mainly involves the acquisition and control of vulcanization temperature. In temperature control, a digital incremental PID adjustment function is added. According to the characteristics of rubber processing plants, the entire system should have functions such as process flow screen display, curve trend graph display, data storage, real-time fault alarm and report printing, historical data query, formula change, and process flow change. In order to ensure that the entire distributed measurement and control system can operate safely, reliably, and with high performance, and considering the future expansion needs of users, the entire system adopts the following design ideas: (1) The system adopts a three-level distributed network structure, consisting of an engineer management station and field measurement and control stations. The engineer management station manages and schedules the field measurement and control stations it monitors. Through hotkey switching, it can also uniformly manage and schedule each field measurement and control station in the entire distributed measurement and control system. Each field measurement and control station is responsible for several field input/output (I/O) units, and they are independent of each other. They jointly complete the data acquisition, control, and communication functions of each field measurement and control station, so as to ensure that the system does not lose control when a certain field I/O unit or a certain field measurement and control station fails. (2) The field engineer station connects to the plant information processing workstation and the chief engineer's station via a fast Ethernet network for future interconnection with the Internet. (3) The system adopts a bus-type field communication network, which has multiple master protocols, high communication speed, real-time capability, error correction, and strong noise suppression capability. At the same time, the system has certain expansion capabilities. (4) The hardware adopts a modular structure: all field units use intelligent measurement and control modules, and all are plug-in or screw terminal wiring, so that maintenance personnel can easily and quickly replace them in case of failure without affecting normal production. According to user requirements, when the system is running normally, from the perspective of signal acquisition and control process, this system is divided into 4 independent parts: compounding agent weighing section substation; rubber mixing section substation; rubber vulcanization section substation; and finished product repair section substation. Each part is equipped with 1 engineer station to collect and control data. At the same time, the engineer stations of the four parts are required to be able to back each other up. When one engineer station fails, the system enters emergency management state through hotkey switching, and the other 3 engineer stations temporarily manage the system. Considering applicability, advanced technology and low system cost, the fieldbus adopts the CAN (Controller Area Network) bus [2] [3]. It is an advanced fieldbus widely used in industrial automation and has the following significant characteristics: It is a high-speed serial bus with a multi-master protocol, and any two nodes on the network can directly exchange data. It has real-time capability. The CAN network uses non-destructive bit bus arbitration technology to handle the conflict of multiple nodes accessing the network at the same time, thereby meeting the real-time requirements and ensuring no data loss and bandwidth loss. Broadcast data communication. The CSMA/CD protocol is used for bus control and data communication. When a node sends data to the network, all other nodes receive the data at the same time. High transmission reliability. CAN is particularly suitable for networked intelligent devices, meets ISO11898, has a transmission rate of up to 1Mbps, a transmission distance of 1000m, and uses differential voltage and twisted pair as the transmission method and medium. The driver/receiver is 64/64, which can be expanded to 256 through the CAN bus expander. Based on user requirements, this engineering workstation solution uses the Advantech IPC610P industrial PC from Taiwan, with a main frequency of 233MHz. To meet bus requirements, an Advantech PCL841 dual-channel isolated CAN bus card is configured within the industrial PC. It supports connection and communication between the industrial PC and the CAN network, with a maximum transmission rate of 1Mbps. This significantly improves the communication speed compared to the industrial PC communicating via RS-232 through the ADAM4525 and then to the CAN network. The field intelligent unit uses the Advantech ADAM5000/CAN product. It is primarily used for independent data acquisition and control, and can communicate with the host computer via its CAN network interface, making it particularly suitable for fieldbus-based data acquisition applications. The ADAM5000/CAN has a built-in 16-bit microprocessor, four module slots (supporting 64 I/O points), and a built-in CAN port. It has sufficient field response capability and I/O processing capacity. It also supports direct interface between field stations and the CAN network (optional DeviceNET or CANopen protocol), and includes built-in hardware and software self-testing and a watchdog timer. The ADAM5000/CAN uses an interrupt-driven approach to perform state change functions. During a state change, data is generated only when the data changes, and then broadcast to all devices on the network. The computer or controller receives the data simultaneously with the event. The field I/O modules utilize the ADAM5000 series, featuring a compact size, conforming to fieldbus trends, and offering three different data acquisition methods: data acquisition, analog output, and digital I/O. This facilitates the easy integration of field I/O devices into computer application networks. It boasts flexible system design, ease of installation and networking, suitability for industrial environments, and extensive software support. The field I/O modules are divided into analog output modules, analog input modules, digital input modules, digital output modules, and thermocouple (RTD) input modules according to the actual control needs of the field. The main functional modules used are as follows: Analog signal acquisition: ADAM5017 (8 channels), Analog signal output: ADAM5024 (4 channels), Digital signal output: ADAM5056 (16 channels), Digital signal input: ADAM5052 (isolated, 8 channels), Thermocouple input: ADAM50 (3 channels), Relay input: ADAM5068 (8 channels). The process control flow consists of four parts: the control flow for the compounding agent weighing section, the control flow for the rubber mixing section substation, the control flow for the rubber vulcanizing section substation, and the control flow for the finished product repair section substation. These four sections are managed by corresponding engineering workstations. Each section is further divided into several field stations, and each field station monitors several field I/O units in real time, forming a four-level management system. The data acquisition and monitoring process is as follows: Each field I/O unit transmits corresponding field environmental parameters in real time. The ADAM5000/CAN field monitoring and control station collects the values ​​of its respective field I/O unit in real time. Then, the ADAM5000/CAN reports some important data to the engineering station via the CAN bus. The engineering station performs logical judgments and real-time processing based on the various analog and digital signals monitored in real time, forming historical data, providing real-time alarms, and displaying the operating status of each field monitoring and control station. Simultaneously, it generates necessary control parameters, which are then transmitted to the ADAM5000/CAN field station via the CAN bus. The ADAM5000/CAN field station then controls the corresponding field actuators in real time through digital and analog output modules to adjust the field working environment. For user convenience, functions such as screen display, trend graph display, data storage, real-time fault alarm, and report printing are required. Therefore, a configuration-based design method is adopted in the software design. The application software uses Windows window technology and features a brand-new Chinese browser interface. The graphical user interface makes operation more intuitive, convenient, and flexible, and the window interface is more user-friendly. The application software adopts the fieldbus communication protocol, which has the advantages of multi-master, real-time, high reliability and low system hardware cost, enabling the application software to run stably in harsh working environments and reducing the risk of the entire network. The software function engineer station completes the detection, control and management tasks of the corresponding sub-network. As a tool for engineers, it enables the sub-network to operate with low power consumption and safety. Its main functions are: (1) Inspection, storage and real-time display of sub-network operating parameters, so that engineers can view the real-time and historical data of the sub-network at any time, thereby conducting unified detection and management of the sub-network. (2) Analyze the operating conditions based on the real-time parameters of the sub-network, promptly discover various abnormal phenomena in the sub-network, analyze possible faults in the system, and promptly display alarms. (3) Print various reports and records at any time, including: alarm printing, timed report printing, and operation record printing. (4) Display various information, including: date and time display, process screen display, group control display, trend display, operation instruction display, etc. (5) Formula management and simple and practical report processing system; (6) Self-tuning of various advanced control algorithms and their parameters. The functions of the field station include: real-time data acquisition, processing and display; real-time fault alarm and display; real-time monitoring of field equipment; software modules In order to enable the system to have the functions of screen display, curve trend graph, data storage, real-time fault alarm and report printing, the software is divided into the application of the secondary engineer station and the application of the field station. Among them, the application of the secondary engineer station has the following major functional modules: (1) initialization module; (2) control parameter setting module; (3) communication module; (4) data acquisition module; (5) field/remote control module; (6) data recording, query and report printing module; (7) fault diagnosis alarm module; (8) production process flow screen display module. The application of the field station has the following major functional modules: (1) initialization module; (2) control parameter setting module; (3) control parameter setting module; (4) data acquisition and display module; (5) fault monitoring and alarm module. In order to ensure the stable operation of the system, the system has taken the following important measures: (1) the network adopts non-destructive bus arbitration to avoid the disadvantages of communication failure and data loss caused by each communication device competing for the bus. (2) CRC checksum is used to enable the communication system to have strong error detection and correction capabilities. (3) Online sub-network monitoring is implemented, with each network serving as a backup. (4) Watchdog technology is used to ensure that the system will not crash under strong interference. (5) Digital filtering technology is used in the software. The system adopts fieldbus control technology and uses a CAN network structure, which greatly improves the reliability and real-time performance of the entire measurement and control system. The entire system adopts advanced design concepts, ensuring its advanced nature. The entire system has been running stably and reliably for a year, and has created certain economic and social benefits for the enterprise.