C # And The Host Link Plc Network Communication-based Design And Realization

This subject researched and developed a communication software which provided the real-time data transmission and exchanging service for the Programmable Logic Controller (PLC) network in Windows. The software was based on the C#.NET and the Host Link protocol. The number of the devices, or the nodes of the network, and the memory areas of the data transmitted of the PLCs and PCs can be changed in the software's configuration. And the relationships of the PLCs and the optical data couplers (ODC) can be set as well. The application of the subject was a project of an Automated Storage & Retrieval System (AS/RS) which had several channels and turnaround cranes. All of the PLCs on the cranes communicated with the upper controller through the ODCs. The system would switch the communication ports of the ODCs linking to the PLCs on the cranes automatically and frequently, and would lock the available currently in order to obtain the available link. All of the status of the communication system and the devices of the network can be show in the GUI dynamically.The AS/RS was applied to a quartermaster depot. So the greatest reliability of the system was needed. Every part of the system should be tested straitly especially the part of the communication. The system would be in manual mode and lose its automatic functions if the communication system was down.The whole communication system was composed by the special devices, the network and the special-purpose software. The software ran in a personal computer (PC) and was in charge of the real-time data transmission and exchanging for the distributed PLC network. The structure of the network and the electrical layouts were designed according to the requirements. The framework, the structure and the detail of the every part of the system software were designed by the UML and the object oriented theory. And many appropriated and efficient design modes were applied during the development. We chose C#.NET to implement the codes. A port auto matched function was developed in accordance with the plan of the turnaround cranes and the ODCs. The software imitated and substituted the Data Link function of the ControllerLink FA in the part of the data transmissions. It was easy and flexible to set up the communication. The performance and the reliability of the software were good and satisfying. The graphic interface was friendly and intuitionistic. The reason why we choose C#.Net is appropriate for the RAD of the strict demanded Windows software because of being superior to C++ and VB6 in the functions and the speed of the development.The subject was a typical example in the area of industrial control and the AS/RS that it was combined with the PLC control technology and PC control technology. And it was a completed, successful and general-purposed solution of the PLC network real-time data transmission. The PCs were entirely competent for the mission of the real-time data transmission in the network which were rely on the strong software technology and the variety of the communication interfaces in Windows. The software has been running steadily since the project was accomplished one year ago. And there was almost nothing wrong with the part of the communication system during that period.