Patent ID: 7536109
Filing Date: 2009-05-19
Classification: H04J

Abstract:
1. An optical network system comprising: a master unit that executes the transmitting and receiving of optical signals between itself and other devices through an optical transmission line; and slave units each of which executes the transmitting and receiving of optical signals between itself and other devices through an optical transmission line; wherein the slave units, from the slave unit at highest rank to the slave unit at lowest rank, are interconnected in the form of a direct chain configuration through an optical transmission line; the master unit is connected to the slave unit at the highest rank through an optical transmission line, and executes the transmitting and receiving of optical signals between itself and the slave unit of the highest rank through the optical transmission line, and between itself and the slave unit except the slave unit of the highest rank through other slave unit and the optical transmission line located between the slave unit and itself; the master unit determines whether or not a period during which a specified action is not requested to itself has been continued for a certain period of time or longer; and when determined as having been continued, transmits an optical signal for polling including a code requiring a predetermined response to the slave unit at the lowest rank; each of the slave units receives optical signal transmitted thereto through the optical transmission line, generates a clock signal, latches a value represented by the optical signal received in response to the clock signal; and generates an optical signal representing latched value; the slave unit at the lowest rank receives the optical signal for polling including the code, transmits the predetermined response to other slave units through the optical transmission line, the predetermined response requesting initialization of clock signals of the other slave units; and the slave units other than the slave unit at the lowest rank receives the predetermined response, and initialize the clock signals of themselves so as to synchronize with the clock signal generated by the slave unit at the lowest rank.