| Fieldbus is the technology which is applied to realize bi-directional, serial, multi-node digital communication between field device and master-control centre. Nowadays Fieldbus is widely used on control system design of industrial manufacture. The traditional mode of distributed and computer layered control have been gradually substituted by the mode of intelligent terminal and network control.The difference of fieldbus in protocol standard often brings complexity to practice and affects the opening and interoperability of the buses. Therefor, the protocols converter is need to interconnected to different buses.In the thesis, protocol conversion module for HBS and RS-232/485 is designed and developed based on a variety of fieldbus standard coexistence and incompatibility of communication protocols. The common characteristics of fieldbus technology have also been summarized.Secondly, the possibility to achieve protocols conversion module and software-hardware composition of protocols conversion modules are analyzed and conceived on the basic of OSI Seven-Layer Model, model of fildbus and the characteristics of communication protocols. Finally, it is proposed using a microprocessor to achieve protocols conversion module for RS-232/485 and HBS.For different fiedbus and different protocols, the protocols conversion module which uses Renesas's H8/3687 chip was designed and developed in the monitoring-conditioning system of a program which adopts RS-232/485 for the upper computer (Smart Home System) and HBS for lower computer (commercial air conditioning systems). The module makes use of MITSUMI ELECTRIC's MM1192 chip for HBS and Maxim's MAX232/485 chip for RS-232/485,and then the suitable peripheral circuits are built.The control program for functional modules, which implements the interconnection between RS-232/485 and HBS is completed. The compatibility and interconection are also completed. The protocols converting module that followed K-Link protocol for communicating with upper computer and H-LINK protocol for communicating with lower computer can successfully complete data exchange between upper computer and lower computer.In practice, the protocols converting module is able to timely send information including run or stop mode, fan level, wind direction, temperature setting, return air temperature, alarm code etc to the Smart Home System. The module could make the users understand the state of air-conditioning. Moreover, it achieved the direct connection between the Smart Home System and the air-conditioning system in the setting run or stop mode, fan level, wind direction, temperature etc.More and more people are now concerned about the compatibility and the openness issues of fieldbus technology. And the protocol conversion module design has also been an new trial in this field. The fruits of this research have been already applied to new products for massive production. This has therefore laid a very solid foundation for further study of interconnection between the communication protocol conversions. It is of great practical significance. Researches have fully proved that this novel and creative method is capable of bearing fruitful and valuable results, having definitely paved the way for the application of protocol conversion module to more manufacturing industries in the near future. |
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