[en] A special distributed control system (DCS) was developed to carry out the reactor control in a floating nuclear power plant, and dual CPU redundant technique was an important method to improve the DCS system reliability. The dual CPU redundant technique based on DeviceNet field bus was researched, in which two CPU units and some data I/O units were connected through a DeviceNet field bus, and DeviceNet client/server programs running in the CPU units implement the data synchronization between two CPU units and the redundant control over data I/O units. (authors)