Research Of The Programmable RTU Based On Ethernet

RTU (Remote Terminal Unit) is a remote control unit, which can monitor and control signal or industrial equipment. Compared with the PLC (Programmable Logic Controller), RTU usually has excellent communication capability and mass storage capacity. The PLC has a considerable share in the industrial field for many advantages, such as programmable, easy to learn and so on. It is significant to develope a new control terminal that combines advantages of RTU and PLC.Comparing domestic and foreign products, this dissertation presents a new programmable RTU based on ethernet. This RTU not only can be used for ethernet communication, but also realizes the secondary programming. So it improves the adaptability of RTU.This dissertation includes four parts:①h ardware design;②design and implementation of the RTU integrated development environment;③design and implementation of RTU bottom program;④c ommunication of PC and RTU.RTU integrated development environment (IDE) was developed with Microsoft's visual C++, which was also major and difficult part in this dissertation.Based on introducing instruction list language and ladder diagram language,the interface design, data structure design, syntax check, compiler design.The software can compile instruction list language and ladder diagram language, and transform two languages each other.RTU bottom software was programmed on ADS IDE, and C language was selected as development language.Usingμc/os-Ⅱas operating system of RTU, can increase the RTU reliability, real-time performance, maintainability. The program included five tasks: keyboard task, LCD display and function option task, ethernet communication task, time task and LED indication task. The communication between the tasks and interrupt services used mailbox and semaphore provided by theμc/os-Ⅱ. Each task is independent, and all of them are manipulated by theμc/os-Ⅱ.The communication module achievd data transmission between RTU IDE and the RTU, it used two modes, serial interface and ethernet interface, to download program and monitor remote data.