COMMUNICATION SYSTEM HAVING A PLURALITY OF COMMUNICATION NODES

• US 20110029704A1
• Filed: 07/29/2010
• Published: 02/03/2011
• Est. Priority Date: 07/29/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: ITOU, Akito, Kimoto, Yuu
• Granted Patent: US 8,347,009 B2
• Time in Patent Office: Days
• US Class Current: 710/110
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 12/40163 by assigning priority to messages according to a message field
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN

Abstract

A certain ECU transmits a reference message for requiring the other ECUs to transmit data. After transmission of the reference message, each of all the ECUs transmits priority information of its transmit message onto a communication bus, and then detects whether some priority information transmitted from the other ECUs has a higher priority than its own transmitted priority information. If there is detected no priority information of a higher priority than its own transmitted priority information, it transmits a message associated therewith, and then is prohibited to transmit data of the same priority until receiving a next reference message.

Claims

1. A communication system comprising

a communication bus and a plurality of nodes connected to the bus, the nodes being able to detect data transmitted onto the bus and including a node predetermined as a master node and one or more nodes predetermined as specific nodes,

wherein the master node comprises first transmission means for transmitting a reference message for requiring other nodes to transmit their own transmit data;

and

each of the specific nodes comprises second transmission means for upon having received the reference message from the master node, transmitting priority information indicative of a priority of its own transmit data onto the bus,

detection means for detecting whether some priority information transmitted by the other nodes indicates a higher priority than its own transmitted priority information,

third transmission means for if there is detected no priority information transmitted by the other nodes indicative of a higher priority than its own transmitted priority information, transmitting its own corresponding transmit data onto the bus and then prohibiting itself to transmit data of the same priority as its own transmitted data until receiving a next reference message from the master node, and

retransmission means for if there is detected some priority information transmitted by the other nodes indicative of a higher priority than its own transmitted priority information, retransmitting its own priority information onto the bus after the transmit data associated with the detected higher priority information has been transmitted from the corresponding other specific node.

2. The system of claim 1, wherein the master node stores in itself the lowest priority information that indicates the lowest priority among priority information to be transmitted by the individual specific nodes, and the first transmission means is further configured to, upon the master node having received the lowest priority information, retransmit the reference message next to the transmitted data associated with the lowest priority information from the corresponding specific node.

3. The system of claim 1, wherein the first transmission means is further configured to, once a reset reference time period set to be longer than a time period required for the individual specific nodes to sequentially transmit all their own transmit data has elapsed after the previous transmission of the reference message, retransmit the reference message.

4. The system of claim 3, wherein each of the specific nodes further comprises deletion means for, upon the reset reference time period having elapsed after the last transmission of the reference message from the master node, deleting transmit data in a transmit buffer adapted to store its own transmit data prior to actual transmission.

5. The system of claim 1, wherein at least one of the specific nodes further comprises issuance means for, upon having received read reference information being predefined priority information, issuing an instruction for acquiring data in a receive buffer adapted to store data received via the bus.

6. The system of claim 1, wherein each of the specific nodes further comprises generation means for generating checksum data with respect to a plurality of pieces of data it has transmitted and priority information transmission means for transmitting priority information predefined for the generated checksum data as well as the generated checksum data.

7. The system of claim 6, wherein the generation means is configured to, upon the specific node having transmitted its own predefined transmit data, generate the checksum data.

8. The system of claim 6, wherein the generation means is configured to generate the checksum data each time a predetermined checksum reference time period has elapsed.

9. The system of claim 1, wherein at least one of the specific nodes comprises first notice means for if a first predetermined anomaly detection reference time period or more has elapsed after the master node has transmitted the last reference message, transmitting an anomaly notice indicative of an anomaly in the master node.

10. The system of claim 1, wherein at least one of the specific nodes stores in itself the lowest priority information that indicates the lowest priority among priority information to be transmitted by the individual specific nodes, and further comprises second notice means for if the lowest priority information has not been detected for a second predetermined anomaly detection reference time period or more, transmitting an anomaly notice indicative of an anomaly.

11. The system of claim 2, wherein the first transmission means is further configured to, once a reset reference time period set to be longer than a time period required for the individual specific nodes to sequentially transmit all their own transmit data has elapsed after the previous transmission of the reference message, retransmit the reference message.

12. The system of claim 11, wherein each of the specific nodes further comprises deletion means for upon the reset reference time period having elapsed after the last transmission of the reference message from the master node, deleting transmit data in a transmit buffer adapted to store its own transmit data prior to actual transmission.

13. The system of claim 12, wherein at least one of the specific nodes further comprises issuance means for, upon having received read reference information being predefined priority information, issuing an instruction for acquiring data in a receive buffer adapted to store data received via the bus.

14. The system of claim 13, wherein each of the specific nodes further comprises generation means for generating checksum data with respect to a plurality of pieces of data it has transmitted and priority information transmission means for transmitting priority information predefined for the generated checksum data as well as the generated checksum data.

15. The system of claim 14, wherein the generation means is configured to, upon the specific node having transmitted its own predefined transmit data, generate the checksum data.

16. The system of claim 14, wherein the generation means is configured to generate the checksum data each time a predetermined checksum reference time period has elapsed.

17. A communication node connected to a communication bus and predetermined as a specific node, wherein the communication bus is communicably connected to communication nodes one of which is predetermined as a master node, the nodes are able to detect data transmitted onto the bus, and the master node transmits a reference message for requiring other nodes to transmit their own transmit data, the communication node predetermined as the specific node comprising:

First transmission means for upon having received the reference message from the master node, transmitting priority information indicative of a priority of its own transmit data onto the bus,

detection means for detecting whether some priority information transmitted by the other nodes indicates a higher priority than its own transmitted priority information,

second transmission means for if there is detected no priority information transmitted by the other nodes indicative of a higher priority than its own transmitted priority information, transmitting its own corresponding transmit data onto the bus and then prohibiting itself from transmitting data of the same priority as its own transmitted data until receiving a next reference message from the master node, and

retransmission means for if there is detected some priority information transmitted by the other nodes indicative of a higher priority than its own transmitted priority information, retransmitting its own priority information onto the bus after the transmit data associated with the detected higher priority information has been transmitted from the corresponding other specific node.