Abstract: This paper presents a tubing cleaning monitoring system implemented using OMRON PLC and King View, based on the actual situation of the Zhenwu Tubing Repair Center in Jiangsu Oilfield. The system structure, hardware design, communication methods, and software design principles are described in detail. The system has been put into operation and has shown good application results. Keywords: PLC; King View; tubing; hot cleaning 1. Introduction Programmable Logic Controllers (PLCs), with their high reliability, adaptability to industrial process environments, 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. Meanwhile, industrial control configuration software is used on the system's host computer (usually an industrial PC) to display the industrial process and control parameters, thereby achieving monitoring and management functions. This control system fully utilizes the respective characteristics of microcomputers and PLCs, achieving complementary advantages and gaining widespread application. In the early 1990s, most oilfields in China cleaned the inner and outer walls of tubing directly on-site using high-temperature steam generated by boiler trucks. This method caused environmental pollution and the cleaning effect was not ideal. With the scaling up and specialization of oilfield production, most oilfields established tubing repair units, assigning specific personnel and equipment to handle tubing cleaning, inspection, and repair processes. Domestic oilfields mainly use three methods for cleaning: high-pressure rotating water jet cleaning, medium-frequency heating cleaning, and high-temperature hot washing. Based on the actual situation of the Zhenwu Tubing Repair Center of the Well Operations Department of Jiangsu Oilfield, a computer monitoring system was designed, using an Advantech Pentium III industrial control computer and an OMRON CQM1H-CPU21 PLC as the hardware core and KingView 6.01 as the software platform, to perform high-temperature hot washing operations on the tubing. The overall system design is shown in Figure 1. The following analysis examines the high-temperature hot washing process for tubing 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 washing tank via a bypass pipe. Considering the large volume and weight of the oil pipes, making manual handling inconvenient, and the high-temperature and hazardous environment of the hot washing room, a mechanical roller transmission, cylinder lifting, and mechanical chain lifting device are adopted. Magnetic, photoelectric, or mechanical limit switches are used to limit the oil pipe movement or control the roller and cylinder actions. The entire process system design uses an OMRON CQM1H-CPU21 PLC as the control core. The CPU21 itself has 16 digital I/O points, which are expanded through four external input modules ID212 and three output modules OC222 to meet design requirements. The PLC is connected to an industrial computer via a COM port and integrated with KingView software to achieve computer monitoring and operation functions. A simplified hardware configuration diagram 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 solution 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 solution. The 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 pipe to the inner wall flushing machine for inner wall flushing. After flushing, the first conveyor line reverses, and the pipe retracts to the discharge sensor on the second conveyor line. The discharge flap activates, flipping the pipe to the second conveyor line. After the discharge flap returns to its original position, the water control cylinder activates for the second water control. After water control, the second conveyor line rotates forward, transmitting the 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 the advanced domestic configuration software, KingView 6.01. KingView is a configuration software with a fully Chinese interface that runs on Windows 98/NT/XP. It employs new technologies such as multithreading and COM components, fully utilizing Windows' graphical editing capabilities to easily construct monitoring screens. It has rich device drivers, flexible configuration methods, and data linking functions. Using it to construct a monitoring system can significantly shorten development time and ensure system quality. Communication between KingView and the PLC uses the PPI communication protocol. KingView communicates with the PLC through a serial port, accessing the relevant register addresses of the PLC to obtain the status of the devices controlled by the PLC or modify the values ​​of relevant registers. In actual programming, it is not necessary to write programs to read and write PLC registers. KingView provides a data definition method; after defining I/O variables, the 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 implemented the following functions: animated display of the process flow, providing a clear view of the operation of each transmission line, water pump, and motor, as well as the number of oil pipes in the hot washing tank and the shift output. Furthermore, different system operation permissions and passwords are set for different operators, and system operation assistance is provided. The system control interface is shown in Figure 4. 4. Conclusion The author's innovation lies in the design and application of KingSCADA and PLC for communication, which offers advantages such as good timeliness, high speed, high reliability, stable operation, and flexible adjustment. The system's human-machine interface is user-friendly and intuitive, possessing a certain degree of flexibility and easy expansion. The system was completed and put into production in 2001 and has been operating normally for 5 years, with stable, safe, and reliable operation. In particular, the combined application of PLC and KingSCADA 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] KingSCADA 6.0 User Manual. Beijing Yacon Technology Development Co., Ltd., 2000 [2] Zhuang Lijuan, Wu Liyun. Design of wastewater system based on PLC control. Microcomputer Information, 2005, 1: 24, 118