A plurality of zones is formed in a communication network on the vehicle, and a communication path in a loop form is formed in each zone by zone trunk lines and a backup line. The backup line is connected by a switch only at the time of disconnection so that the loop is not closed. At the time of disconnection detection, an instruction is automatically given to rewrite content of routing maps on zone ECUs and a central gateway. Since each node preferentially selects a communication path that bypasses a disconnection portion from the start of communication by rewriting the content of the routing maps, it is possible to avoid an increase in communication delay. An inter-zone backup line connecting a plurality of zones is provided to enable the use of a new path across the plurality of zones at the time of disconnection.

A system for time synchronization over redundant switch-based avionics networks is disclosed. The system includes a master or source clock for determining precise UTC timing information from received satellite signals and generating time marks based on the timing information. The source clock generates network-compatible timing messages and forwards the timing messages to network switches within the switch-based avionics networks. The network switches modify the timing information to account for switch-based delays and forward the modified timing messages to destination clocks in aircraft end systems. The end systems relay timing messages back to the source clock via the network switches, the timing information again modified by the network switches according to switch-based delays, and based on the precise timing information exchanged destination clocks in end systems throughout the switched network can precisely synchronize to the source clock.

A communication path in a loop form is formed by trunk lines and a redundant communication path, which is formed by a switch and a backup line. In order to be applied to a bus-type communication network such as a CAN, the switch is normally off, and the backup line is disconnected from a path in a steady state. A disconnection detection unit is provided at each of joint connectors. When any disconnection detection unit detects disconnection, the switch is closed to enable use of the redundant path. Further, content of a routing map of a central gateway is automatically rewritten to preferentially select the redundant path that is not disconnected, and thus the path is changed.

There is provided a communication failure detection device configured to detect a communication failure of a two-wire CAN communication device that makes communication between nodes according to a CAN protocol. Each of the nodes is provided with two signal detection circuits configured to detect signals on the two communication lines. Each node makes communication for failure dentification to output signals of predetermined patterns onto the two communication lines when an execution condition is satisfied in response to the occurrence of a protocol error of CAN communication. Each node then performs failure identification to identify the type of a failure based on a combination of the signals respectively detected by the two signal detection circuits during the communication for failure identification.

A system of communicating data over a high availability industrial control system is disclosed. The industrial control system includes a first data producer, a second data producer in communicative connection with the first data producer, a first data consumer, and a second data consumer in communicative connection with the first data consumer. The system further includes the first producer communicating the data over multiple connection paths from the first producer to the first consumer and the second consumer through intermediate modules, and the second producer communicating the data over multiple connection paths from the second producer to the first consumer and the second consumer through intermediate modules. Also disclosed is a method of communicating data over the high availability industrial control system.

A route failure and a device failure are detected in a short time without erroneous recognition. A multiplexing system includes: a first system having a pair of processing devices forming a pair; a second system having a pair of processing devices forming a pair that are different from the first system; each processing device of the first system and the second system includes a survival monitoring unit configured to monitor a failure of the each processing device or the each LAN based on a device time-out for confirming survival of the each processing device and a route time-out for confirming survival of the each LAN set to be longer than the device time-out.

In an anomaly determination method for determining an anomaly in a received message, a plurality of messages which include messages that are periodic and each of which includes a first field having a fixed value and a second field having a variable value are each received as the received message, and one of a plurality of combinations to be used for determination each of which includes at least one of a plurality of anomaly determinations including an anomaly determination utilizing a reception timing based on the periodicity or the number of received messages, an anomaly determination utilizing the first field, and an anomaly determination utilizing the second field, is selected according to one or more criteria among available execution time of the anomaly determination method, a load amount, a data amount, and the number of messages.

In an anomaly determination method for determining an anomaly in a received message, a plurality of messages which include messages that are periodic and each of which includes a first field having a fixed value and a second field having a variable value are each received as the received message, and one of a plurality of combinations to be used for determination each of which includes at least one of a plurality of anomaly determinations including an anomaly determination utilizing a reception timing based on the periodicity or the number of received messages, an anomaly determination utilizing the first field, and an anomaly determination utilizing the second field, is selected according to one or more criteria among available execution time of the anomaly determination method, a load amount, a data amount, and the number of messages.

Provided are an in-vehicle communication apparatus, a communication program, and a message transmission method. The in-vehicle communication apparatus according is connected to another apparatus via a plurality of communication lines, and includes a plurality of communication units that are provided respectively for the communication lines, and transmit/receive a message via the communication lines, a classification processing unit that performs processing for classifying messages that are to be transmitted to the other apparatus, into a plurality of groups in accordance with priorities of the messages and a message transmission processing unit that distributes messages classified into each of the plurality of groups, to one or more communication units allocated to the group, and the number of communication units allocated to a group into which a higher-priority message is classified is larger than the number of communication units allocated to a group into which a lower-priority message is classified.

In accordance with an embodiment, a method includes determining whether a frame received from a communication bus is encoded according to a particular communication protocol and is addressed to a particular electronic device; increasing a frame count value when the frame is encoded according to the particular communication protocol and is addressed to the particular electronic device based on the determination, wherein increasing the frame count value comprises increasing a count of a modular arithmetic counter circuit having a first bit depth, and the frame count value is constrained to a modulus value of the modular arithmetic counter circuit; setting a frame count status bit based on comparing the frame count value to threshold values, and transmitting a frame comprising the frame counter status bit over the communication bus, and resetting the frame count value at an end of a monitoring time interval.