The Design And Implementation Of PLC Equipments’ Remote Monitoring Software Based On C/S Model

With the in-depth study of PLC products, the application scope of PLC has been expanded from the field of the traditional simple industrial control to process control, distributed control and motion control, digital control. The contradiction formed by the high usage rate of PLC equipment and its extensive and complex application environment, is constantly prompting PLC to remote monitoring direction. However, the current PLC monitoring software is mostly used locally or within the enterprise, which have poor real-time performance and portability and narrow range of application. In order to ensure the safe and stable operation of PLC, improve the ability of making decisions and debugging of equipment failure, as well as reduce the impact and risk caused by failure, the development of reliable and stable remote monitoring software for PLC equipment has far-reaching significance. To meet the requirements of PLC owners and manufacturers, the paper developed remote monitoring software combined with the computer technology, network and serial communication technology.Firstly, by the discussion of the background and significance of the research and the introduction of the research status of PLC equipment and remote monitoring technology at home and abroad, the paper defines its research content and objectives. Then, the paper analyses the functional and non-functional requirements of software, the overall architecture, the communication scheme and the development environment of the software on the basis of the system composition and operating principle.The remote monitoring software is based on C/S structure, including a server and a client. The server consists of two parts:database and application server. Based on the user demand, the conceptual structure and logical structure of database, the database builds related entity tables, stored procedures, and the strategies of performance optimization. And the details of the database transaction processing are described. According to the function, the application server can be divided into data management server which is oriented to client and database, and equipment monitoring server which is oriented to PLC, client and database. The mainly design targets of server are monitoring module, transmission module and database transaction processing module base on the single responsibility principle. The communication scheme is realized by multi-thread and thread pool technology.The client is design with MFC programming, network communication, and virtual serial port technology, which can be divided into user interface layer, data processing layer and communication layer. The communication layer implements asynchronous communication by using Socket which is based on TCP/IP communication protocol and implements sending and receiving data by using multi-thread technology. Data processing layer is the logical implementation part of user interface functions, and it interacts with communication layer. The user interface layer mainly discusses the development of information management, data monitoring and process monitoring module.Finally, in order to verify whether the PLC remote monitoring system meet every design requirement, the paper makes various types of tests, such as communication test, function test and compatibility test. The running result indicates that the software is stable and reliable, realizing the predetermined requirements.