在现代化工业生产中,PLC 和现场总线等自动化设备的应用越来越广泛。为了防止 PLC 故障造成不必要的生产停顿和安全性问题,目前,PLC 各生产厂家都推出了双机热备份产品。对于中小型控制系统,采用一些已成型的双机热备份产品会显得成本过大,因此,本文基于欧姆龙PLC,讨论了通过软件方式实现双机热备份的方法。 关键词:PLC,双机热备份,RS-232C,软件,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