This paper presents a configuration of high reliable distributed control systems (DCS). We have proposed DCS which utilize multiplexed control programs without adding any redundant controllers. And it also has been designed a extended Triple modular redundancy (TMR) for remote Input/Output in order to instead a function of fault detection. Reliability analysis have been carried out and reliability of the proposed systems have been calculated to compare full duplex structure and basic model. Mean Time To Failure (MTTF) of Analysis result is proved the proposed method achieves higher reliability than conventional full duplex systems, especially in the repairable condition. Furthermore, experimental results are demonstrated and confirmed that fault-tolerance of the proposed system is functional.