[b]1 Introduction[/b] Distributed Control System (DCS), also known as distributed control or centralized control system, is developed based on single-loop microcomputer control system. It integrates computer technology, communication technology, CRT display technology, and process control technology. It adopts a hierarchical structure and the design principles of decentralized control, centralized operation, hierarchical management, and decentralized autonomy, solving the shortcomings of past computer control systems, such as concentrated dangers, limited functionality of conventional analog instruments, excessive dispersion, and inconvenient human-machine interaction. The safety, reliability, versatility, flexibility, and excellent control and comprehensive management capabilities of DCS have led to its widespread application in industrial control. Corrugated cardboard, as a commonly used packaging material, is widely used in the packaging of electrical products, daily necessities, etc. In my country, where the level of modern large-scale industrial automation is relatively backward and industrial and economic construction is developing rapidly, continuous production processes are formed by units such as cross-cutting machines and stacking machines. Currently, the domestic corrugated cardboard production is relatively underdeveloped. This monitoring system adopts a distributed control system based on programmable logic controllers (PLCs). The PLCs serve as field acquisition and control stations, utilizing Ethernet and Profitbus for data communication. This system enables the display of operating conditions, production operations, order management, and shipment management of the Jialong corrugated cardboard production line in Zhaoqing, Guangdong, ultimately achieving integrated enterprise management and control. [b]2 System Overall Structure and Communication Network[/b] 2.1 System Overall Structure The Jialong corrugated cardboard production line monitoring system adopts a distributed computer monitoring system as shown in Figure 1. It has a three-level structure: field level, control level, and management level. The first level is the field level. Three PLC substations installed on-site, along with other measurement and control equipment (such as encoders, infrared measuring instruments, frequency converters, etc.), perform various data acquisitions and on-site control of the production line. The field acquisition controller completes the input and output of field signals, processes data according to the given working procedure, outputs control data, and sends the processing results to the operator station. The PLC station uses products from VIPA, Germany, and includes one CPU station and two I/O stations, equipped as follows: V200 CPU station: mainly includes modules such as CPU 288L, FM250, SM221, and SM222. It is mainly used for acquiring various status signals and outputting control signals for the gluing machine and the cross-cutting machine. V200 station 1: mainly includes modules such as SM221, SM222, SM232, and FM250; mainly used for acquiring status signals and outputting control signals for the gluing machine and corrugating machine No. 1. V200 station 2: mainly includes modules such as SM222, SM232, and FM250; mainly used for acquiring status signals and outputting control signals for corrugating machines No. 2 and No. 3. The second level is the control level, equipped with 5 industrial PCs. This includes 1 main operator station, 1 gluing machine operator station, and 3 corrugating machine operator stations. The main operator station is located in the workshop control room, and the other operator stations are located in their respective parts of the production line, completing the management of field-level detection, control, and protection functions. A hub connects all operator stations into a local area network. Each operator station operates independently yet can serve as a backup for others. It processes, analyzes, and stores all data collected from the first-level field, collects and issues all control commands, and expresses the overall production line's operational status in various ways (such as flowcharts and trend charts). System configuration, flowchart creation, protection value setting, and control model modification are also performed on this level of operator station. The third level is the management level, equipped with multiple ordinary PCs, printers, and a database server. The PCs serve as management terminals in the relevant management departments, the printers are responsible for periodically printing production reports for archiving, and the database server is responsible for receiving and storing various real-time and historical data from the supervisory control level. Managers in each department can observe the production line's operational status and order execution at any time through the management terminals. The management level also accepts input data from management departments to perform order management and shipment management functions.