| Profibus-DP is one of the most widely used field bus in the world which is used for high-speed data communication between controllers and distributed I/O as well as field devices. Because of its simple installation,various topological structure and reliable real-time communication, Profibus-DP is suitable for many kinds of automation field. Meanwhile industrial ethernet is penetrating rapidly into industrial control field. With the improvement of communication speed and reliability ,ethernet is gaining increaslying stronger real-time performance and can even meet the strict real-time requirement of field device layer. While considering further its advantage in openness and monopolistic application in commercial communication field , industrial ethernet is becoming a incresaing severe challenge to field bus ,though its application in industry is still restricted by unsatisfactory perfomance price ratio. According to the specific control requirements of crossbelt sorter system, this paper designs a process control system based on industrial ethernet and Profibus-DP while integrating both of their advantages.The main contents of this paper are as follows:1,Firstly this paper introduces the industrial ethernet technology and field bus technology which both represents the trend of industrial communication,then introduces some communiction protocols and methods of industrial communication networks adopted by SIEMENS S7 system,aiming at the specific application of the system designed in this paper, and then describes OPC technology which is uesd for communication between PLC and upper computers, finally introduces the Profibus-based mobile communication between controllers and moving mechanisms with conductor rails as the transmission medium.2,This paper describes the hardware configuration of the whole system, including control devices and some important drivers and actuators such as linear motors (LIM), frequency convertors,automatic bar code scanner and so on. Based on these ,describes the design of communication scheme in the sorter system .including the division of network layers and specific application of various communication technologies, among which the design of the high-speed mobile communication scheme with conductor rails as the transmission medium is the main innovative point of this paper.3,Based on detailed analysis of the functions of control nodes in the system,this paper constructs the time series model about data exchange among different nodes with the software tool Rational Rose,and optimizes the direction and size of data exchanged among these control nodes after analyzing the control flow, and finally establishes the communication protocol in the application layer of system.4,This paper introduces the software platform for developing themain control system , detailedly describes the hardwareconfiguration of PLC system,the network configuration and theOPC communication configuration , and analyzes the softwareimplementation of the main control system , including analysisof some important function modules and control flows.The design thought of hybrid network with both field bus andindustrial ethernet can achieve the integration of monitoring, control, management and decision-making, under the current situation that the cost is still too high to fully apply industrial ethernet to industrial field layer, it can commendably meet the requirement of real-time performance and high reliability in industrial system while effectively controlling the cost, so has a bright application prospect. |
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