FCS165 fieldbus control system is an automation control system used for monitoring, control, and protection of main and auxiliary control systems as well as information and equipment management in large-scale thermal power plants. This system not only provides all functions of advanced DCS, but also allows seamless integration of Profibus field bus technology. It serves as the basis for digitalized power plants. FCS165 field bus control system adopts world class electronics, communication, computer, and control technologies, with overall function and performance reaching internationally advanced level. This system has been successfully used in the main and auxiliary control systems of all 2×600MW ultra-supercritical air-cooling units in Huaneng Qinling Power Plant.