The Research Of Realizing Redundant System Based On The S7-200PLC

In the field of modern industry, with automatic control technology consistently being broad and deep applied, the research of system reliability is gradually paid close attention, so as to promote the continuous development of reliability technology.Redundancy control is a kind of effective means which could satisfy the requirement of continuous production, redundancy technology as one of the effective techniques to improve the reliability of system having developed rapidly. PLC(Programmable Logic Controller) with its high reliability and strong anti-interference ability is also widely used in the field of industrial automation. In pursuit of a higher reliability, in adapting to the high reliability of applications, PLC redundancy technology is also developing rapidly。Being relative to small control system, the cost of using the PLC with the redundancy function(such as S7-300/400, etc.)is too high. By using S7-200 controller,the system can achieve and meet the requirements of control system performance and high reliability, therefore, the research on this subject has good technical value and social economic value. How to use the redundancy technology based on PLC to the small control system is the focus of this paper, this Subject theory is based on the PLC control technology, the Modbus communication technology, the background of process control and so on, and a set of redundancy plan was designed based on S7-200 PLC, and carry out the corresponding experimental research.At first, the application situation of PLC redundancy system both at home and abroad were analyzed, combining with Siemens S7-200 PLC control principle and the communication principle of the Modbus protocol. A reasonable system control plan was selected, and the implementation principle of the redundant system was designed. Then the S7-200 PLC redundancy system hardware platform was built, and the reliability of redundant system was studied. After those according to the different methods of PC and PLC communication, the software of the S7-200 PLC redundancy system was designedby using STEP 7- Micro/WIN programming software. At last, using Kingview software in PC configuration, the experimental application of redundant system was debugged and monitored.Through the experiment research analysis shows that the switching between workstations and standby station in this redundancy control system is implemented. The impact of fault on the system can be greatly reduced. The reliability of the system without stopping running will be improved, and there will be great development space and market in the field of control system.