Study And Realization Of Communication Gateway Between Ethernet And Rs485 Based On μc/os-Ⅱ System

The traditional industrial control system began to develop into network and openness with the development of network technology. The deliver and sharing of industrial concrol imformation is not only in control layer,but also bond with information network. All of that have offered huge convenient for Information sharing of enterprise and global. Recently, Ethernet has been widely applied in the upper management in the industrial control area for the advantage of the low cost, high speed and facilitated information sharing and webbing.But control layer usual use fieldbus, RS485 bus as one of the multipoint difference data transmission electrical code has become one of the most wide used standard communication interface in industries.This paper start from the developmental situation of control network and information network, it analyse detailedly about the characteristic of the fieldbus and ethernet, and it also introduce a kind of method to design a gateway which is embeded theμCOS-II real-time operating system, which is used to resolve the issue of communication between RS485 bus and Ethernet. Meanwhile this paper put forward a software design approach on save first and get after, this approach can effectively improve communication speed and simplify the data structure and ethernet length, so it makes upper computer easy operate, simplify program, and have good generality and portability.This topic based on to satisfy the demand of the practical project application, firstly, it summarizes the fieldbus and ethernet current situation and development. Secondly, it introduces detailedly about network structure and principle of work in fieldbus and ethernet, it includes Modbus and Tcp/Ip protocol standard, andμCOS-ⅡRTOS, and on the basis above it, the paper discuss the network structure and protocol conversion design idea and network model of'μCOS-Ⅱ+Modbus+TCP/IP'scheme. thirdly, this paper introduces detailedly about the hardware system realization and software system design process, in there it includes hardware architecture, interface description, parts of circuit theory introductions, software system design flow,parts of codes, and every model realization.lastly, this paper shows system realization and function debug process, it discusses code space,system operating efficiency and reliability problem. There gives analysis and solutions to the problem I encountered in debug process. This topic provided a reference for the design of the hybrid network data transmission system.