Abstract: A communication network including relay devices connected in a ring shape is provided. A master relay device transmits an abnormality detection frame from one of two specific ports at fixed time intervals in a frame circulation direction. When neither the frame abnormality detection nor an abnormality notification frame transmitted from another relay device is received from the other of the two specific ports within a predetermined time period from transmission of the abnormality detection frame, the master relay device specifies an occurrence of an abnormality in a communication path between the master relay device and a relay device connected next to the master relay device in a direction opposite to the frame circulation direction.

Abstract: A repeater is implemented as switches, each having ring-connection ports. In an address table in each of the switches, a list of hop numbers is stored as additional information in addition to the addresses, listing hop numbers to each of destination devices for the ring-connection ports in association with an address. When a communication controller in each of the switches finds the same destination address stored in the address table for the ring-connection ports, the communication controller selects, from the address table, one of the two destination addresses for the ring-connection ports having a smaller hop number as a transfer destination of the frame, thereby enabling the frame to take a shortest possible communication route to the destination devices.

Abstract: A communication network includes relaying apparatuses, each including redundant-route ports providing communication routes between the relaying apparatuses. The relaying apparatus determines whether a first frame received via a usual port is highly important. The first frame being highly important is transmitted via the respective redundant-route ports; the first frame being not highly important is transmitted via one redundant-route port. The relaying apparatus receives a second frame being highly important via the respective redundant-route ports; the second frame has a transmission destination corresponding to an apparatus connected with the relaying apparatus via the usual port. The relaying apparatus makes determination whether or not all the second frames received via the respective redundant-route ports accord with each other. With affirmative determination, one of the second frames is transferred to the transmission destination. With negative determination, all the second frames are cancelled.

Abstract: A relaying apparatus in a communication network has ports and a memory storing an address table where addresses of apparatuses connected to the respective ports are registered. The ports include a first and second particular ports to be connected in the communication network permitting a broadcast frame having been transmitted via the first particular port to be received via the second particular port. Upon receiving the broadcast frame via the second particular port, the relaying apparatus makes a determination whether or not a transmission-source address of the received broadcast frame is registered to a port other than the first and second particular ports in the address table. The relaying apparatus cancels the received broadcast frame when making the determination affirmatively.

Abstract: A relay apparatus which relays a communication among a plurality of control devices includes a plurality of ports connected with the plurality of control devices, respectively, via a plurality of communication lines; a determination section determining whether a reception frame received by each of the plurality of ports is normal or abnormal; a discarding section discarding the reception frame when the determination section determines that the reception frame is abnormal; and an abnormality notifying section, when the determination section determines that the reception frame is abnormal, notifying an abnormality occurrence in the reception frame to a transmission source device, wherein the transmission source device is one of the control devices that transmitted the reception frame.

Abstract: A network control device includes a communicator performing communications via a transmission line at a preset transmission speed in a wake-up mode, a low frequency attenuator attenuating a low frequency component in a transmission signal having a low transmission speed that is lower than the preset transmission speed at a position between the transmission line and the communicator to receive and transmit the transmission signal to and from the communicator, and a wake-up controller receiving and transmitting a wake-up signal for transitioning from a sleep mode to the wake-up mode, at a transmission line side position of the low frequency attenuator, where the wake-up signal at a low frequency band is subject to attenuation by the low frequency attenuator, for a selective wake-up of a network node via the transmission line for network communications.

Abstract: A signal transmission circuit includes a transceiver, an impedance adjustment circuit, a first control circuit and a second control circuit. The impedance adjustment circuit realizes a low impedance state and a normal state of the transmission line. The first control circuit controls the impedance adjustment circuit to realize the low impedance state for a fixed period that is shorter than a width of one bit, when a change of a signal level on the transmission line is detected. The second control circuit controls the impedance adjustment circuit according to a transmission data transmitted from the transceiver, when detecting that a communication frame wins an arbitration by comparing the transmission data and the received data, to realize the low impedance state in an entire period where the signal level on the transmission line is recessive until transmission of the communication frame ends.

Abstract: A signal transmission circuit includes a transceiver, an impedance adjustment circuit, a first control circuit and a second control circuit. The impedance adjustment circuit realizes a low impedance state and a normal state of the transmission line. The first control circuit controls the impedance adjustment circuit to realize the low impedance state for a fixed period that is shorter than a width of one bit, when a change of a signal level on the transmission line is detected. The second control circuit controls the impedance adjustment circuit according to a transmission data transmitted from the transceiver, when detecting that a communication frame wins an arbitration by comparing the transmission data and the received data, to realize the low impedance state in an entire period where the signal level on the transmission line is recessive until transmission of the communication frame ends.

Abstract: An electronic device includes an electronic part and a wiring substrate. The electronic part includes a rewiring substrate, a semiconductor chip, and solder bumps arranged in a matrix form. The wiring substrate includes a wire and lands arranged in a matrix form corresponding to the solder bumps. Each of the lands is coupled with corresponding one of the solder bumps so as to form connection portions. The connection portions include nonfunctional connection portions that do not provide an electric connection between the semiconductor chip and the wire. The lands forming the nonfunctional connection portions include a power source land and a ground land arranged next to each other in a row direction or a column direction. The lands that are arranged next to the lands forming the nonfunctional connection portions in the row direction or the column direction are set to signal lands.

Abstract: An electronic device includes an electronic part and a wiring substrate. The electronic part includes a rewiring substrate, a semiconductor chip, and solder bumps arranged in a matrix form. The wiring substrate includes a wire and lands arranged in a matrix form corresponding to the solder bumps. Each of the lands is coupled with corresponding one of the solder bumps so as to form connection portions. The connection portions include nonfunctional connection portions that do not provide an electric connection between the semiconductor chip and the wire. The lands forming the nonfunctional connection portions include a power source land and a ground land arranged next to each other in a row direction or a column direction. The lands that are arranged next to the lands forming the nonfunctional connection portions in the row direction or the column direction are set to signal lands.