Design And Implementation Of Programmable Remote Terminal Unit

With the subsidization of Shanghai University Technological Progress Fund, Industrialization of Research Project of SHNU and SHNU Youth Fund, this issue was established. Its goal is to design an new RTU with long-term stability which can work in the industrial environment of no duty, and as the core equpiment of SCADA system, it can achieve the function about remote controling, remote sensing, remote signaling, and remote regulating. RTU was named UPRTU by Pilot Projects.The hardware and software of the RTU adopt all modular design, support programmable function, have an independent integrated development environment and support for graphical programming language.As the principal, the author divides the design of UPRTU into three parts: integrated development environment (IDE), CPU module and input/output modules(I/O). The project presented by this paper is completed by our group working together. The author is in charge of the project design including analysing requirements of the design, advising the design goal, establishing model of the goal, suggesting entire project, defining communication protocol between UPRTU and computer, pseudo-code as well as other parts of the interface in order to coordinate various parts of the parallel design. Beside these, the author also participates in a number of specific R&D work, such as the CPU module(part) and the I/O module design.The author advises a scheme of tree intermediate data structure to achieve that Ladder Diagram compile to the transitional document and then translate to the Pseudo-code document in IDE; And the author designs the virtual machine of RTU to execute document of the Pseudo-code in embedded Linux platform of the CPU module; At the same time, the author designs a MODBUS Protocol to implement upload and download of this Pseudo-code. As a sub-Protocol, it can be compatible with MODBUS to avoid seizing and conflicting COM port. This paper designs a custom CAN application layer protocol, which gives full play to the the characteristics of the CAN about much maters in bus, and also adapts to requirements of transmission of I/O data. CPU module manages I/O modules through the CAN application layer protocol.The prototype of UPRTU has passed the test. Prototype tests show that its performance reaches the objectives of the design, accords with the applied demand and achieves the advanced level of similar technology in China.