Research On Fieldbus Device Networks

Fieldbus is a core technology of modern industrial automation and control system.It makes industrial automation and control system have distributed, open, highlyintelligent features. It also makes industrial measurement and control products of thedifferent types and different manufacturers be easily connected. It greatly enhances theefficiency, stability and adaptability to the environment of industrial automation andcontrol system, and reduces the cost significantly.Fieldbus device network is an essential part of the fieldbus system, its performanceis of great important to the industrial control system. At present, fieldbus is in thecondition of multi-standard co-existing and will be co-existence in long-term, theapplication layer protocols of each instrument manufacturers, the system integrators andindustry professions have a lot of differences, and the industrial environments are alsovarious. This situation leads to a lot of problems still existing in fieldbus devicenetworks, include compatibility, network management efficiency, network anti-interference performance, etc. This thesis works in the following three areas to studyand cope with these problems:1) Design and implement an embedded platform, whichhas the abilities of protocol conversion, computation, data storage, forwarding andsignal repeating. The platform is mainly to solve the problem of data compatibility andprovide the support to the optimization of network scheduling.2) The network structureand scheduling method are improved, and the structure of fieldbus network which basedon four ports, two sets of twisted pair connections and sub-meter relay is designed. Anetwork scheduling method of hierarchical and cluster management is present, and thesystem’s stability and speed of the whole network patrol are improved.3) For somestrongly electromagnetic interference environment, a data transfer method which basedon spread spectrum technology is proposed. This method can greatly improve noiseimmunity while reduces the transmission rate less.In this thesis, we verify the validity of embedded platform designed through theapplication, and verify the effectiveness of the proposed network structure, scheduling,and data transferring through simulation.