Industrial Ethernet-based Distributed Measurement And Control System

Fieldbus technology, which is called the computer LAN in the automatic field, is one of the focuses of the technical development in current automatic field. As the base of industrial digital communication network, it is used for communicating between the control devices of production process scene level and production process scene level ,even the higher control management level. But so far as situation at present, the development of fieldbus technology still has a great deal of questions, such as the different fieldbus protocols, the high price of development tools, etc. So everyone is looking for a single common standard. As Ethernet and TCP/IP communication technology obtaining enormous success in IT trade, people turn sight to Ethernet, and apply it to the industrial automatic field.Basing on the analysis of Ethernet technology and TCP/IP protocol, this thesis researches the realization of observe and control system through Ethernet chip RTL8019AS. The system communication net is basing on 10M Ethernet and conformed to TCP/IP protocol. The collection of the input signals in scene and the control of the output signals can be finished long-rangly through this system. This thesis introduces the development of industry Ethernet, TCP/IP protocol and the change that is done in order to be suitable for the realization of the microprocessor. How to make the whole network protocol system keep the same with the communication protocol and give consideration to the embedded system with the characteristic of little spacing and compact structure is one of the important problems solved in the design. The design and realization of the top-management-card in the scene control workstation is described afterwards. The top-management-card adopts ATmega128, which has a large flash and high speed. It is mainly used to manage the I/O cards (with CAN bus interface), communicate with the computer through Ethernet and realize some simple control arithmetic without theinterference of the computer. The scene control workstation can work independently under the control of the top-management-card.The I/O module, which works in scene and is used to collect real-time signals and control the devices, is also an important component of the system. This thesis introduces the design of I/O module taking RTD module as an example. The computer software is very important, too. It can realize the configuration of this system, the renewal of the application program of the top- management-card and the real-time control to the data in scene. Finally , the PID control based on BP neural network is studied.Because of the system adopting Ethernet and TCP/IP protocol as the main communication standard, it can be visited through the long-range communication media. It really reflects the open spirit of industry basic automation and makes the automatic system be networked, intelligent and digitization. It also simplifies the system structure of the industrial automation, and improves the globality and stability of the industrial automation, making it more strengthen and efficiency. As a result ,the investment of enterprises for industrial automation will be reduced finally.