Abstract: A communication device operating as a hub in a train network system that includes a plurality of hubs installed in train vehicles, each of the plurality of hubs belonging to both a trunk network in which a signal transmission range is not limited and a branch network in which a signal transmission range is limited, and adding, to a signal to be transmitted to a hub belonging to the same branch network as it does, network type information indicating whether the signal is a trunk network signal or a branch network signal. The communication device transmitting branch network information including at least identification information on a branch network to which it belongs at a predetermined timing, and based on branch network information received from an adjacent communication device, determining whether or not to add the network type information to a signal to be transmitted to the adjacent communication device.

Abstract: A train-information managing apparatus receives a series of control information attached to serial numbers, which are transmitted from a central apparatus, in order of the transmission and carries out control in the order, and even when the central apparatus is changed or the serial numbers are reset, prevents a blank period of control from occurring. Therefore, when a reception serial number n included in received data is a preferential serial number (n?M) and an old number nprev, which is a serial number included in data received and stored last time, is a cyclic serial number (nprev?M+1), the train-information managing apparatus stores the received data.

Abstract: A communication device operating as a hub in a train network system that includes a plurality of hubs installed in train vehicles, each of the plurality of hubs belonging to both a trunk network in which a signal transmission range is not limited and a branch network in which a signal transmission range is limited, and adding, to a signal to be transmitted to a hub belonging to the same branch network as it does, network type information indicating whether the signal is a trunk network signal or a branch network signal. The communication device transmitting branch network information including at least identification information on a branch network to which it belongs at a predetermined timing, and based on branch network information received from an adjacent communication device, determining whether or not to add the network type information to a signal to be transmitted to the adjacent communication device.

Abstract: A second-system terminal device installed in one vehicle is connected to a first-system backbone transmission line and a second-system backbone transmission line, and when having received a status information packet B from a first-system terminal device installed in another vehicle from the first-system backbone transmission line or the second-system backbone transmission line, the second-system terminal device installed in the one vehicle transfers a control packet A to the second-system terminal device adjacent to a side farther from a central device than the second-system terminal device that has received the status information packet B, by using the backbone transmission line from which the status information packet B has been received.

Abstract: A train-information managing apparatus receives a series of control information attached to serial numbers, which are transmitted from a central apparatus, in order of the transmission and carries out control in the order, and even when the central apparatus is changed or the serial numbers are reset, prevents a blank period of control from occurring. Therefore, when a reception serial number n included in received data is a preferential serial number (n?M) and an old number nprev, which is a serial number included in data received and stored last time, is a cyclic serial number (nprev?M+1), the train-information managing apparatus stores the received data.