Abstract: This paper introduces a monitoring system for a robotic welding production line based on a client/server architecture. The design goals, structure, and functional implementation of the system are described. Keywords: Client/server; Monitoring system; PLC With the deepening application of computer technology in the field of industrial automatic control, networked monitoring systems have emerged and represent the mainstream direction of development in the field of automation. Based on network technology and supported by the powerful hardware performance of modern computers, it achieves real-time monitoring of automated production through simple and rapid software development. Modern enterprises combine upper-level management information systems with lower-level field control systems, enabling managers to view the enterprise as an organism from a holistic perspective while also understanding its detailed production data. This allows for a comprehensive understanding of production, planning, scheduling, and management from both macro and micro perspectives. Using this monitoring system, managers can check the operation of the production system, collect and display process parameters, and set and modify them through simple operations, thus achieving efficient off-site management. Based on the author's experience in the transformation of the robotic welding production line at Nanjing Iveco Automobile Co., Ltd., this paper focuses on the design goals, system structure, and functional implementation of a monitoring system for a robotic welding production line based on a client/server architecture. 1. Design Objectives of the Monitoring System The robotic welding production line of Nanjing Iveco Automobile Co., Ltd. consists of six Italian COMAU-120 robots. Currently, the company's supervision and management of the production line is mainly limited to the workshop control level. The robot welding status and alarm information can only be obtained on-site. The plant-level scheduling and management are still in the initial stage of transmitting information by telephone and manually processing reports. This greatly reduces the company's production efficiency and the real-time and reliability of management. In view of this situation, it is more urgent to establish a safe and reliable networked monitoring system. The system monitors and controls the operating equipment scattered in different locations through an interconnected network to realize data acquisition, equipment control, measurement, parameter adjustment and various signal alarm mechanisms. The monitoring system should specifically realize the following functions: (1) Automation of manual operation; (2) Centralization of robot program loading and setting; (3) Coordination of the six machines by the monitoring system; (4) Globalization of management information; Through the realization of the above monitoring functions, the goal is to improve the processing time of the production line, reduce the failure rate, shorten the troubleshooting time, thereby improving the production efficiency and benefits of the production line, and improving the level of production management. 2. System Composition The entire production line network monitoring system consists of field control units (mainly PLCs), robots, servers (i.e., monitoring computers), management computers, communication modules, and RS-232 communication cables. The structural block diagram is shown in Figure 1: [align=center] Figure 1 Monitoring system structure using Client/Server mode[/align] Due to various reasons on site, and considering that the advancement of industrial Ethernet technology has made it possible for Ethernet to penetrate the field, this system adopts Ethernet communication. 3. System Function Implementation (1). Hardware Implementation The objects that need to be monitored in the production line are: robots, welding controllers, workpiece transmission lines, and air, water and power sources. From the perspective of fault analysis, the more links monitored, the more conducive it is to fault location, but too many measuring points will inevitably increase the complexity of the system and investment. Therefore, measuring points should not be set for every link, but some important links that are prone to failure should be selected for monitoring. [align=center]Figure 2 Network Communication Diagram[/align] The Siemens S5-115U PLC used on-site. The PLC centralizes most of the signals, which can be transmitted to the monitoring computer. There are two ways to connect the S5-115U PLC to the monitoring computer: PROFIBUS and Industrial Ethernet. Here, we use the PLC as a remote data acquisition device for the monitoring system's data acquisition unit, and the monitoring computer communicates with the PLC using PROFIBUS. Robot information can be transmitted through the robot controller's RS-232 serial port. Since RS-232 can only perform point-to-point communication and the communication distance is less than 15 meters, its communication capability needs to be extended. In the monitoring system, we convert the robot's serial interface using an RS-232/ETHERNET converter to connect the robot to the Ethernet. The network communication diagram is shown in Figure 2. This method is relatively simple to implement. A communication module IM308-C is added to the PLC. Since the PLC itself is a control device, its reliability is guaranteed. The monitoring computer adds a communication module CP5613 and communication software (PROFIBUS driver). The robot is connected to the Ethernet via an RS-232/ETHERNET converter. (2). Software implementation This system is based on the client/server model, so the software implementation of the system can be divided into two layers: the PLC, robot and server communication submodule and the server and client communication submodule. The PLC, robot and server communication submodule is used to realize the communication between the PLC, robot and server (i.e., the monitoring computer) to complete the acquisition of real-time production data; the server and client communication submodule is used to realize the communication between the monitoring computer and the management computer to complete the transmission of real-time production information, laying the foundation for the scheduling, management and decision-making of upper-level managers. For the communication between the PLC and the monitoring computer, we use the monitoring computer as the master station and the PLC as the slave station, and use the configuration software COM PROFIBUS for configuration initialization; for the communication between the robot and the monitoring computer, we use VC++ for programming. For the communication between the server and the client, the database server uses Microsoft SQL Server 2000 DBMS, the client application development uses Borland's Delphi 5.0, and the server and client applications use the OBDC connection method. A user-friendly and intuitive interface was built using Delphi 5.0, including a main monitoring interface, a historical data interface, an alarm interface, and a management interface. These interfaces display the operating status of each robot, record real-time operating data and alarm status, and archive the data. Users can also query data and print reports. 4. Conclusion This paper discusses a design method for implementing a networked robotic welding production line monitoring system in a client/server environment. Field devices communicate via Ethernet. Based on this, a user-friendly interface was designed using Delphi 5.0 programming technology, allowing operators to intuitively and dynamically monitor the production process and respond promptly to alarm information and emergencies. Simultaneously, the collected real-time production data and fault information can be provided to the enterprise's operations and management departments, achieving internal information sharing and joint control, thereby improving the technological content of the production process. References 1. Institute of Automation, Southeast University. Preliminary design scheme for monitoring of Nanjing Iveco robot body welding production line. 2002 2. Wang Haopeng, Du Xiuhua. An implementation method of real-time information network communication in production. Computer Engineering 2001, 27(1): 48 3. Cao Yong, Su Meijun. Application and system development examples of real-time computer monitoring in automated production process. Manufacturing Automation, 2001, 23(9): 42 4. Liu Yi. Delphi5 enterprise-level solutions and application analysis. Beijing: Machinery Industry Press. 2000 5. Shan Siqing (ed.). SQL Server 7.0 system management and application development guide. Beijing: Tsinghua University Press, 2000