CHINA_4_MASKED The Xiangjiang hydro-junction located in the center of China contributes to shipping, water supply, flood control, livability and travel in that area. Its navigation lock is the first duplex lock capable of handling 2000 tons of shipping each way, and the lock gates are the largest in all of China’s inland rivers, measuring 20m high, 20m wide and weighing 300 tons. The control system has to work in a very hostile environment. It is responsible for local control and supervisory control, remote control, system diagnosis, data transmission and so on. Eight lock gates are located in up-river and down-river ends of the lock, and each gate has its own control cabinet. All the control cabinets are linked to the control center for centralized management. Besides control data, a large amount of video monitoring data from cameras beside the river must be transferred and the whole system must work in real time with high reliability and flexibility. After comparisons with two fieldbus solutions, a PROFINET system was chosen by the customer, with PROFINET PLC, PROFINET IO, PROFINET switches and so on. A redundant PROFINET PLC located in each control room controls locally through a PROFINET IO station. A 3km redundant fiber connection links the PLC pairs. Each redundant PLC is linked via PROFINET fiber too. The PROFINET control system has been running for more than a year, contributing a new control concept for the hydro-junction industry in China. PHOENIX CONTACT