Research On The MODBUS TCP/IP Based Supervisory Control And Data Acquisition System Of Equipment

Unified supervisory control of factories and enterprises field equipment by connecting them to the information network will become one of the most important elements that the next generation of enterprise informationization bases on.At present in the factory and enterprise applications,most of the equipment use RS-422,RS-232,RS-485 serial link and communication protocols to connect theirself to a control network.However,the effective radius of the network is relatively limited and generally isolated from the outside of the information network,then connecting the field equipment control network to the information network has great significance.To achieve the interconnection between the scene equipment control network and the information network,on the one hand,the communication protocol of the field equipment control network are different from the one of the Ethernet information network,so it is important to solve the question of protocol conversion,then the traditional serial data can be sent on the Ethernet without the need to prematurely eliminate the original equipment,thereby improving the utilization of existing equipment,saving the investment,and also simplifying the complexity of cabling on the existing network infrastructure.On the other hand,Ethernet has universal application in the information network,and in order to have the information network of Interact capacity,more than 90 percent of Ethernet run TCP/IP protocol,so in order to achieve the unified management of scene equipment control network and information network,we must comply an application layer protocol that the information network can use for communication on Ethemet TCP/IP.MODBUS TCP/IP application layer message transmission protocol is a good solution.This paper based on the Rabbit 3000 microprocessor industrial properties and its powerful development environment,designs a embedded gateway that can realize the communication between the field equipment control network and the Ethernet TCP/IP information network,so the field equipment layer can connect to the information management layer.On this basis,based on the need of data flow between the information network and the control network and the unified management of field equipment in the factories and enterprises,this paper develops the supervisory control and data acquisition system of equipment based on Ethemet MODBUS TCP/IP to realize centralized supervisory control for field equipment.The framework of the whole supervisory control and data acquisition system of equipment is composed with three client/server model:the first client/server model based on MODBUS master/slave station on serial link,the second client/server model based on MODBUS TCP/IP protocol on Ethemet and the third software client/server model based on DDE.After debugging and experimentation,The supervisory control and data acquisition system of equipment can be applied in Chaozhou City CHINA TELECOM Air-conditioning Supervisory Control And Energy-saving System to realize unified Supervisory Control of Air-conditioning and automatic control.The supervisory control and data acquisition system of equipment runs well and stably.