Abstract: Provided are a communication system, an abnormality detection device and an abnormality detection method that detects abnormality concerning communication such as information forged by utilizing a difference in timings of sampling between multiple communication devices. For the system configuration where ECUs transmit and receive information through a common communication line, abnormality detection related to communication is performed by a monitoring device connected to the communication line. Each ECU receives information by sampling once at a predetermined timing during a transmission period of one-bit information. The ECUs may also be allowed to perform sampling at different timings.

Abstract: Provided are a communication system and a communication device that allow a reception node to estimate delay time, a generation time point or the like of a message. A delay time estimation part in an ECU determines whether a message received by itself is transmitted in sequence with another message without being provided with time information by a transmission node. If the received message is transmitted in sequence with another message, the received message may be delayed due to arbitrary processing. Thus, the delay time estimation part checks the priority of one or more sequential messages preceding the received message, and estimates delay time of the received message occurring due to the arbitrary processing in accordance with the priority of each message. A generation time point estimation part estimates the time point when the received message is generated by an ECU, based on the delay time estimated.

Abstract: Provided are a communication control device and a communication system capable of detecting message transmission in the case where an invalid device transmits a message to a common communication line. A monitoring device decides a reference time point t0 for periodical message transmission by an ECU, decides multiple scheduled transmission time points t1, t2, . . . obtained by adding a period corresponding to an integer multiple of a transmission cycle T of a message to the reference time point t0, and decides that a predetermined period including each of the scheduled transmission time points is a permission period for message transmission. The monitoring device determines whether or not a detected message on a CAN bus has been transmitted during the permission period. If determined that transmission of an invalid message is not permitted, the monitoring device performs processing of causing the ECU which receives the message to discard the message.

Abstract: A communication system and key information sharing method which allows first and second communication devices to share key information and perform cryptograph processing. The monitoring device calculates hash value based on copy data of storage content of an ECU, and transmits a part to the ECU as confirmation information. The ECU further extracts a part from a value, obtained by removing confirmation information from hash value calculated by the ECU, and transmits part to the monitoring device as response information when the received confirmation information is included in the hash value calculated by the ECU. The monitoring device determines whether the received response information is included in hash value of the monitoring device or not. The ECU and monitoring device each use residual value, obtained by removing confirmation information and response information from hash value calculated by the ECU or monitoring device, for following cryptograph processing as a shared key.

Abstract: A plurality of ECUs and a monitoring device are connected to a common CAN bus. Each ECU outputs to the CAN bus a transmission frame where authentication information is added to data to be transmitted to the other ECUs. The monitoring device monitors transmission of a frame to the CAN bus, obtains a frame when the frame is transmitted, and determines right or wrong of authentication information contained in the obtained frame. When the authentication information is not right, there is a possibility that the transmission frame is a fraudulent frame transmitted by malicious equipment, therefore, the monitoring device outputs an error frame to the CAN bus before a final bit of an EOF of the transmission frame is outputted to the CAN bus, and causes the EUCs to discard this transmission frame.

Abstract: In a network in which a plurality of ECUs are connected to one another with a common bus, one or more slots are allocated to each ECU in advance, and the plurality of ECUs cyclically transmit messages in an order prescribed in relation to the slots. When each ECU transmits the message related to one slot, each ECU creates and transmits a message including data to be transmitted to other ECUs, and information representing respectively a success/failure of the message reception related to other slots. Each ECU checks information of ACK field included in a message received during one cycle from message transmission related to one slot to a next message transmission related to said one slot. When the message related to one slot is not accurately received by the other ECUs, retransmits the message in the next transmission related to said one slot.

Abstract: Distribution apparatuses include databases for storing data received from ECUs, and further include receiving buffers and sending buffers. The distribution apparatus continuously performs, in parallel, an operation for storing received data on the receiving buffer, operation for synchronizing contents of the database with the databases, and an operation for sending data from the sending buffer. Further, the distribution apparatus periodically copies data of the receiving buffer onto the database and data of the database onto the sending buffer.

Abstract: Relay apparatuses read the attribute values of data, i.e., numerical information representing measurement values, calculation values, control values, etc., from receive buffers in which data received from ECUs connected thereto is stored, and create trunk frames containing the numerical information and transmit and receive trunk frames via trunk lines. The relay apparatuses derive numerical information from trunk frames received from the other relay apparatuses and renew the numerical information on the data stored in their respective databases using the derived numerical information.

Abstract: When communication is performed with the upstream and downstream sides being defined in the order of relay apparatuses, the relay apparatuses each transmit a keepalive message representing that they are effectively performing communication. When no keepalive message can be received from the relay apparatus and an abnormality is detected thereby, the relay apparatus transmits a keepalive message including abnormality information representing that the abnormality is detected. By receiving the keepalive message including the abnormality information, the relay apparatus detects the abnormality on the upstream side, changes a communication path, and transmits a master candidate notification to the relay apparatus on the downstream side in order that the relay apparatus itself becomes a master.

Abstract: When sending data, an ECU sends time lag information indicating a time lag that is a difference between time of generating time point at which the data is generated and time of sending start time point at which the ECU actually starts sending the data. When transferring the data, a relay apparatus adds time lag information indicating a time lag that is a difference between time of receiving start time point at which the relay apparatus starts receiving the data and time of transferring start time point at which the relay apparatus starts transferring the data, onto the time lag added on the received data. When receiving the data, an ECU determines for the received data the time of the generating time point that is earlier the time lag indicated by the time lag information of the received data than the time at which the ECU starts receiving the data.

Abstract: An object of the present invention is to provide a sending apparatus, sending method and a communication system with utilizing the sending apparatus that can improve efficiency of data sending operation and can reduce a duty for data communication. Each sending apparatus classifies data stored on a storage into groups “X”, “Y” and “Z”, fractionates a clump of data, classified into each of the groups “X”, “Y” and “Z”, by a number of fractions based on a sending completion allowable time for the classified data, and sends the fractionated data in multi cycles at every sending interval, without sending and receiving the data stored on the storage all at once. Each sending apparatus selects any one piece of data generated from fractionated clump of data for each of the groups “X”, “Y” and “Z”, and then sends the selected piece of data at every sending interval.

Abstract: The relay devices store data received from an ECU connected to each of the relay devices in the first reception buffers, respectively. During a synchronizing period, the relay devices perform transmission and reception by mainline frames including attribute value groups mutually received from the ECUs. Data read out from the databases are transmitted to the ECUs. The databases are synchronized with one another only when the relay device receives the final frame from the relay device which received all the mainline frames and issues COMMIT.

Abstract: In a network in which a plurality of ECUs are connected to one another with a common bus, one or more slots are allocated to each ECU in advance, and the plurality of ECUs cyclically transmit messages in an order prescribed in relation to the slots. When each ECU transmits the message related to one slot, each ECU creates and transmits a message including data to be transmitted to other ECUs, and information representing respectively a success/failure of the message reception related to other slots. Each ECU checks information of ACK field included in a message received during one cycle from message transmission related to one slot to a next message transmission related to said one slot. When the message related to one slot is not accurately received by the other ECUs, retransmits the message in the next transmission related to said one slot.

Abstract: It is provided about a communication system mountable on a car, communication apparatus mountable on a car and a communication method mountable on a car that can perform data transmission under extensive range from a low speed communication to high speed communication, without generating data delay, data dropout and the like, caused by the data sending collision. A gateway and an ECU are connected to each other, in a one-to-one manner, via a communication line different from another communication line for another connection. When receiving a message, the gateway and the ECU reply a receipt response. When having a message to be sent toward the destination for replying at this replying time, the gateway and the ECU sends the receipt response onto which this message to be sent is added. When a message sending collision is generated, the gateway preferentially performs a message re-sending operation.

Abstract: GW apparatuses send messages including data being sent from ECUs to a distribution apparatus without sending to an ECU. The distribution apparatus stores the messages on a database, and sends the messages to an ECU, and an ECU. In a case, the distribution apparatus sends the messages in a message sending order and the GW apparatuses relays the messages being sent from the distribution apparatus to the ECUs. The message sending order may be an order in which the distribution apparatus receives the messages an ascending (descending) order of values corresponding to message IDs applied to the messages or an ascending order of message received time of the messages.

Abstract: The relay devices store data received from an ECU connected to each of the relay devices in the first reception buffers, respectively. During a synchronizing period, the relay devices perform transmission and reception by mainline frames including attribute value groups mutually received from the ECUs. Data read out from the databases are transmitted to the ECUs. The databases are synchronized with one another only when the relay device receives the final frame from the relay device which received all the mainline frames and issues COMMIT.

Abstract: Relay apparatuses read the attribute values of data, i.e., numerical information representing measurement values, calculation values, control values, etc., from receive buffers in which data received from ECUs connected thereto is stored, and create trunk frames containing the numerical information and transmit and receive trunk frames via trunk lines. The relay apparatuses derive numerical information from trunk frames received from the other relay apparatuses and renew the numerical information on the data stored in their respective databases using the derived numerical information.

Abstract: When sending data, an ECU sends time lag information indicating a time lag that is a difference between time of generating time point at which the data is generated and time of sending start time point at which the ECU actually starts sending the data. When transferring the data, a relay apparatus adds time lag information indicating a time lag that is a difference between time of receiving start time point at which the relay apparatus starts receiving the data and time of transferring start time point at which the relay apparatus starts transferring the data, onto the time lag added on the received data. When receiving the data, an ECU determines for the received data the time of the generating time point that is earlier the time lag indicated by the time lag information of the received data than the time at which the ECU starts receiving the data.

Abstract: When communication is performed with the upstream and downstream sides being defined in the order of relay apparatuses, the relay apparatuses each transmit a keepalive message representing that they are effectively performing communication. When no keepalive message can be received from the relay apparatus and an abnormality is detected thereby, the relay apparatus transmits a keepalive message including abnormality information representing that the abnormality is detected. By receiving the keepalive message including the abnormality information, the relay apparatus detects the abnormality on the upstream side, changes a communication path, and transmits a master candidate notification to the relay apparatus on the downstream side in order that the relay apparatus itself becomes a master.

Abstract: Distribution apparatuses include databases for storing data received from ECUs, and further include receiving buffers and sending buffers. The distribution apparatus continuously performs, in parallel, an operation for storing received data on the receiving buffer, operation for synchronizing contents of the database with the databases, and an operation for sending data from the sending buffer. Further, the distribution apparatus periodically copies data of the receiving buffer onto the database and data of the database onto the sending buffer.