OPTICAL FIELD NETWORK SYSTEM

PROBLEM TO BE SOLVED: To obtain an optical field network system with high reliability by allowing network connects to have provision for a duplicate configuration so that no system-down is caused by a fault in the network connector. SOLUTION: The optical field network system is provided with an A/D converter circuit that applies A/D conversion to an analog signal obtained from a sensor Sn measuring an electric quantity of field equipment Gn and outputs AI data, an AI node having a network I/F section Nn that transmits the AI data to an optical field network 2, and a server or a controller Rn that receives the AI data from the optical field network. Thus, a plurality of sensors can transmit analog signals even under a noisy installation environment such as an electric station without any data error to a control building.