在現代化工業生產中，PLC 和現場總線等自動化設備的應用越來越廣泛。為了防止
PLC 故障造成不必要的生產停頓和安全性問題,目前，PLC 各生產廠家都推出了雙機熱備份產品。對于中小型控制系統，采用一些已成型的雙機熱備份產品會顯得成本過大，因此，本文基于歐姆龍PLC，討論了通過軟件方式實現雙機熱備份的方法。
關鍵詞：PLC，雙機熱備份，RS-232C，軟件,OMRON
Abstract: in the modern industry production, automation devices like PLC and Fieldbus are more and more widely used. At present, in order to prevent the unnecessary production intermission and security matter caused by fault of PLC, every PLC manufacturer bring forward their dual controllers backup system. With regard to middling and small system, it is too expensive to adopt the present dual controllers backup system. So author discuss realizing the dual controllers backup system in the way of software based on the OMRON PLC.
Keyword: PLC, Dual controllers system, RS-232C，Software, OMRON