[Abstract]: This paper presents a pipeline cleaning monitoring system implemented using Mitsubishi PLC and MCGS configuration software, based on the actual situation of a pipeline repair center in the Sichuan mining area. The system's structure, hardware design, communication methods, and software design principles are described in detail. The system has been put into operation and its application results are satisfactory. Keywords : PLC; MCGS; oil tube; thermal washing [align=center]The Supervision System Based on MCGS for Oil Tube Thermal Washing Zhenghui (Sichuan Vocational and Technical College, Suining, China)[/align] Abstract: This paper presents a supervision system for oil tube thermal washing implemented by Mitsubishi PLC and MCGS for the Oil Tube Restoring Center of Diggingsin Middle of Sichuan. The system structure, hardware and communication design, and software design are described in detail. The system is already running in the field and works well. Key words : PLC; MCGS; Oil Tube; Thermal Washing 1. Introduction In the early 1990s, most oilfields in China used a method of directly cleaning the inner and outer walls of oil tubes taken from the wellbore with high-temperature steam generated by a boiler truck on-site. This method caused environmental pollution and the cleaning effect was not ideal. With the increasing scale and specialization of oilfield production, most oilfields have established oil pipe repair units, assigning specific personnel and equipment to perform cleaning, inspection, and repair procedures on oil pipes. In the cleaning process, domestic oilfields mainly use three methods: high-pressure rotating water jet cleaning, medium-frequency heating cleaning, and high-temperature hot washing. Programmable logic controllers (PLCs), with their high reliability, adaptability to industrial process sites, and powerful networking capabilities, are now widely used in production processes. In many current automation systems, PLCs are often chosen as the field control devices for data acquisition, status control, and output control, while industrial control configuration software is used on the system's host computer (usually an industrial PC) to display industrial processes and control parameters, achieving monitoring and management functions. This control system fully utilizes the respective characteristics of microcomputers and PLCs, achieving complementary advantages and gaining widespread application. Based on the actual situation of the oil pipe repair center in the Sichuan Central Mining Area, a computer monitoring system was designed, using an Advantech Pentium D industrial PC and a Mitsubishi FX2N PLC as the hardware core, and Kunlun Tongtai MCGS6.2 as the software platform, to perform high-temperature hot washing operations on the oil pipes. The overall system design is shown in Figure 1. The following analysis examines the high-temperature hot cleaning process for oil pipes from both hardware and software perspectives. 2. Hardware Configuration An existing 2T boiler is used to heat the cleaning solution (mainly water, containing appropriate proportions of sodium hydroxide and metal surfactants) in the hot cleaning tank via a bypass pipe. Considering the large volume and weight of the oil pipes, the inconvenience of manual handling, and the high-temperature hazardous environment of the hot cleaning room, a mechanical roller transmission, cylinder lifting, and mechanical chain lifting device are adopted. Magnetic, photoelectric, or mechanical limit switches are used to limit or control the movement of the rollers and cylinders. The entire process system design uses a Mitsubishi FX2N-128 PLC as the control core. It has 128 digital I/O points, which fully meets the design requirements, while also leaving room for future expansion. To allow for on-site processing, the PLC programming port is retained, and an FX2N-485-BD is added to the PLC to connect to an industrial computer and integrate with MCGS software to achieve computer monitoring and operation functions. The simplified hardware configuration is shown in Figure 2. 3. Software Analysis The oil pipe to be cleaned enters the pipe rack inside the hot washing tank via a conveyor line, where it comes into full contact with the cleaning fluid for heat exchange. The crude oil on the inner and outer walls of the pipe melts and peels off, floating to the surface of the cleaning fluid. The oil pipe is then lifted above the liquid surface by a chain lifting device for the first water control. After water control, it is again lifted by the chain lifting device to the first conveyor line. The first conveyor line rotates forward, sending the oil pipe to the inner wall flushing machine for inner wall flushing. After flushing, the first conveyor line rotates backward, and the oil pipe retracts to the discharge sensor on the first conveyor line. The discharge flap actuates, flipping the oil pipe to the second conveyor line. After the discharge flap returns to its original position, the water control cylinder actuates for the second water control. After water control, the second conveyor line rotates forward, transmitting the oil pipe through the outer wall flushing machine for outer wall cleaning. After completion, the pipe is discharged, completing the cleaning operation for one oil pipe. The PLC programming logic is shown in Figure 3. Due to the large number of monitoring points and the complexity of the screens in the entire system, designing the monitoring software in-house would be time-consuming and difficult. Therefore, the host computer was programmed using MCGS, a domestically advanced configuration software. MCGS is a fully Chinese visual configuration software running on the Win95/98/NT/XP platform. It adopts new technologies such as multi-threading, multi-tasking, and COM components. It provides nearly a hundred drawing tools and basic symbols for quickly constructing graphical interfaces and easily building monitoring screens. It has rich device drivers and supports over 1000 commonly used domestic and international devices, including data acquisition boards, intelligent modules, intelligent instruments, PLCs, frequency converters, and network devices. It supports various industrial control curves such as temperature control curves, planned curves, real-time curves, historical curves, and XY curves. Its flexible configuration methods and data linking functions support OPC interfaces, DDE interfaces, and OLE technology, facilitating easy interconnection with various other programs and devices. Using MCGS to construct a monitoring system can significantly shorten development time and ensure system quality. MCGS communicates with the PLC using the RS-485 communication protocol. MCGS configuration software communicates with the PLC via a serial port, accessing relevant PLC register addresses to obtain the status of the PLC-controlled equipment or modify the values ​​of relevant registers. In actual programming, there is no need to write programs to read and write PLC registers. MCGS provides a data definition method; after defining I/O variables, variable names can be directly used for system control, operation display, trend analysis, data logging, and alarm display. Based on the actual monitoring requirements, the designed software implements the following functions: animated display of the process flow, providing a clear view of the operation of each transmission line, pump, and motor, as well as the number of oil pipes and shift output in the hot washing tank. Through the OPC technology provided by the software, Mitsubishi's programming software is integrated into the monitoring interface, making system operation and debugging more convenient. Furthermore, different system operation permissions and passwords can be set for different operators on the main interface, and system operation help is provided, etc. The system control interface is shown in Figure 4. 4. Conclusion The author's innovation is that the design uses MCGS configuration software and PLC for communication, and integrates Mitsubishi programming software on the interface. It has the advantages of good timeliness, fast speed, high reliability, stable operation and flexible adjustment. The human-machine interface of the system is friendly and intuitive, with a certain degree of flexibility and easy expansion. The design was completed and put into production in 2005. It has been running normally for 3 years. The whole system runs smoothly and is safe and reliable. In particular, the combined application of PLC and MCGS software technology has greatly improved the degree of automation in production, reduced the labor intensity of workers, and achieved good practical results. 5. References [1] MCGS6.2 User Manual. Beijing Kunlun Tongtai Automation Software Co., Ltd., 2003 [2] Zhuang Lijuan, Wu Liyun. Design of wastewater system based on PLC control. Microcomputer Information, 2005, 1: 24, 118 [3] Mitsubishi Micro Programmable Controller User Manual [M]. Mitsubishi Corporation, 1998 [3] Ruan Youde Electrical Control and PLC [M] People's Posts and Telecommunications Press, 2006 Author Introduction: Zheng Hui, male, born in 1970, Han nationality, Suining, Sichuan, Master, graduated from Chongqing University in 1991 with a major in Automatic Control, currently working as the director of the Electrical Engineering System Automatic Control Teaching and Research Office of Sichuan Vocational and Technical College E-mail: [email protected] Tel: 13882551883 Mailing Address: Department of Electrical Engineering, Sichuan Vocational and Technical College, Suining City, Sichuan Province 629000