To prevent the discontinuity of data and the disturbance of a transmission sequence accompanied by equal valuing which occurs in a gateway for duplex data transmission.
There are provided in this device a control system memory means 18 which stores whether a protocol conversion device is in either of states of a stand-by system or an active system; a self diagnosis means 15 which discriminates whether the protocol conversion device is in a normal state or in an abnormal state; a state communication means 16 which transceives a signal regarding the normal state or the abnormal state with the other protocol conversion device; and a protocol conversion devices 1a, 1b and a duplex protocol conversion system 7 using them which include a communication route switching means 17 which switches the communication route so as to transmit received data to a controller which is connected to the protocol conversion device which receives the abnormal signal when the received signal of the state communication means 16 is an abnormal signal showing the abnormal state and the protocol conversion device which receives the abnormal signal is the stand-by system referring to a memory content of the control system memory means 18.
COPYRIGHT: (C)2007,JPO&INPIT
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Arihara Koichi
Matsushima Tetsuo
Hidefumi Kawamura
Masayuki Okamoto