Multiplex transmission system

• US 5,606,556 A
• Filed: 12/29/1994
• Issued: 02/25/1997
• Est. Priority Date: 12/30/1993
• Status: Expired due to Fees

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Terayama, Koji, Kawanishi, Toshiaki
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Jung, Min
• Application Number:
  US08/365,862
• Time in Patent Office: 789 Days
• Field of Search: 370/85.1, 370/85.2, 370/85.3, 370/85.6, 370/85.15, 370/99, 370/79, 370/111, 375/219
• US Class Current: 370/471
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: B60R 2016/0322 Temporary code for documents to be reclassified to G08C, H04L or H04Q

Abstract

An object of this invention is to provide a multiplex transmission system which can temporarily use an existing data area as a destination address area and an area for designating data to be transmitted when a communication node of the multiplex transmission system is started or reset, and can prevent unnecessary data other than designated data from being transmitted even when a data sendback request is issued to another communication node to which a transmission request is to be issued. In a multiplex transmission system in which a plurality of communication nodes A to E are connected via a multiplex transmission path MB, each communication node transmits a communication frame in which event data of, e.g., switch ON states of its own lamps, motors, and the like, via the multiplex transmission path MB, and the communication frame is received by all the communication nodes when a communication state is normal, when the communication node A at the transmitting side issues a data transmission request to another communication node D, the communication node A writes data representing that a frame F is a transmission request frame in an existing data area I, and the address of the communication node D which is to receive the frame F and ID(0) to ID(3) of data to be transmitted from the communication node D in data write areas D-0 to D-3, and transmits the frame.

Claims

1. A multiplex transmission system in which a plurality of communication nodes are connected to a multiplex transmission path, each of the communication nodes transmits a communication frame, in which event data of its own node is written onto the multiplex transmission path, and when a communication state is not a predetermined state, the communication frame is received by all the communication nodes,

the communication node at a transmitting side comprising:

frame generation means for generating the communication frame including the event data;

discrimination means for discriminating whether or not the communication state of the communication node at the transmitting side is the predetermined state; and

format changing means for, when it is determined that the communication state is the predetermined state, changing a data format of the communication frame to write data representing that the communication frame is a data transmission request frame in an existing data area of the communication frame to be transmitted from the communication node, and to write an address of the communication node which is to receive the communication frame, and transmitting the communication frame, and

the communication node at a receiving side comprising;

frame transmission and reception means for receiving the communication frame whose data format has been changed, and transmitting a new communication frame in which event data designated by the received communication frame is written.

2. The system according to claim 1, wherein said format changing means writes a type of event data to be transmitted from the communication node designated by the address in the existing data area in the communication frame to be transmitted from the communication node at the transmitting side.

3. The system according to claim 2, wherein the communication frame has a first data area in which the type of the event data is to be written, and a second data area in which the event data is to be written, and when the communication state is the predetermined state, the data representing that the communication frame is the data transmission request frame is written in the first data area, and an address of the communication node which is to receive the communication frame and the type of the event data to be transmitted from the communication node designated by the address are written in the second data area.

4. The system according to claim 1, wherein the communication frame has a third data area in which data representing a priority order used when the communication frame contends with another communication frame, and when the communication state is the predetermined state, the data indicating a top priority order is written in the third data area.

5. The system according to claim 1, wherein said format changing means changes the communication frame to be transmitted from the transmitting side to a data transmission request frame which is to be issued from one to another communication node of the plurality of communication nodes.

6. The system according to claim 5, wherein the data transmission request frame is transmitted when the communication node at the transmitting side recovers from the predetermined state.

7. The system according to claim 1, wherein the predetermined state of the communication state is a state wherein the communication node at the transmitting side is started or reset.

8. The system according to claim 1, wherein the event data is data representing an operation state of a vehicle.

9. A multiplex transmission apparatus which is connected to a multiplex transmission path and transmits a communication frame in which its own event data is written onto the multiplex transmission path, comprising:

detection means for detecting a predetermined condition at a transmitting side;

frame generation means for generating a communication frame to be transmitted from the transmitting side, by changing a data format of the communication frame and writing data representing that the communication frame is a data transmission request frame and an address of a receiving side which is to receive the communication frame in an existing area of the communication frame, on the basis of the detection result; and

frame transmission means for transmitting the communication frame.

10. The apparatus according to claim 9, wherein said frame generation means writes, a type of event data to be transmitted from the receiving side corresponding to the address, in the existing data area of the communication frame to be transmitted from the transmitting side.

11. The apparatus according to claim 10, wherein the communication frame has a first data area in which the type of the event data is to be written, and a second data area in which the event data is to be written, and when the communication state is the predetermined state, the data representing that the communication frame is the data transmission request frame is written in the first data area, and an address of the communication node which is to receive the communication frame and the type of the event data to be transmitted from the communication node designated by the address are written in the second data area.

12. The apparatus according to claim 9, wherein the communication frame has a third data area in which data representing a priority order used when the communication frame contends with another communication frame, and when the communication state is the predetermined state, the data indicating a top priority order is written in the third data area.

13. The apparatus according to claim 9, wherein said frame generation means generates the communication frame to request transmission of event data from the transmitting side to the receiving side.

14. The apparatus according to claim 9, wherein the data transmission request frame is transmitted when the transmitting side recovers from a state wherein the predetermined condition is detected.

15. The apparatus according to claim 9, wherein the predetermined condition is a state wherein said multiplex transmission apparatus is started or reset.

16. The apparatus according to claim 9, further comprising means for transmitting a communication frame in which latest event data of the transmitting side after a response to the data transmission request frame is received.

17. The apparatus according to claim 9, wherein the event data is data representing an operation state of a vehicle.

18. A multiplex transmission apparatus for receiving a communication frame including event data transmitted from a transmitting side via a multiplex transmission path, comprising:

reception means for receiving the communication frame transmitted from the transmitting side;

detection means for detecting whether or not a specific communication frame is received; and

frame generation means for, when it is detected that the specific communication frame is received, generating a new communication frame in which predetermined data designated by the specific communication frame is written, without changing the length of the communication frame.

19. The apparatus according to claim 18, wherein said frame generation means writes its own event data in an existing data area of the communication frame on the basis of the predetermined data designated by the specific communication frame.

20. The apparatus according to claim 18, wherein said frame generation means generates the communication frame to be transmitted from the receiving side to the transmitting side, in which designated data is written.

21. The apparatus according to claim 18, wherein the specific frame is a data transmission request frame which is transmitted when the transmitting side recovers from a state wherein the transmitting side is started or reset.

22. The apparatus according to claim 21, wherein the communication frame has a first data area in which the type of the event data is to be written, and a second data area in which the event data is to be written, and when the communication state is the predetermined state, the data representing that the communication frame is the data transmission request frame is written in the first data area, and an address of the communication node which is to receive the communication frame and the type of the event data to be transmitted from the communication node designated by the address are written in the second data area.

23. The apparatus according to claim 21, wherein the communication frame has a third data area in which data representing a priority order used when the communication frame contends with another communication frame, and when the communication state is the predetermined state, the data indicating a top priority order is written in the third data area.

24. The apparatus according to claim 18, further comprising means for, when it is detected that the specific communication frame is not received, receiving the communication frame in which latest event data at the transmitting side is written, and updating event data which is possessed by the receiving side and is necessary for the transmitting side to the latest event data.

25. The apparatus according to claim 18, wherein said detection means detects whether not an address of the receiving side is written in the communication frame received by said reception means.

26. The apparatus according to claim 18, wherein the event data is data representing an operation state of a vehicle.

27. The apparatus according to claim 18, wherein said frame generation means changes a data format of the communication frame to write the predetermined data designated by the specific communication frame.