JP2947496B2 - Vehicle data transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of electronic control units mounted on a vehicle such as an automobile, and a vehicle data transmission system comprising a common communication line interconnecting these electronic control units.

[0002]

2. Description of the Related Art A plurality of electronic control units (hereinafter, referred to as "ECUs") are connected by a common communication line (hereinafter, referred to as a "network bus"). As a method of avoiding data collision, there is conventionally known a method (a token passing method) in which transmission rights are circulated between ECUs in a predetermined order, and only the ECU having the transmission right can transmit data to a network bus. Have been.

[0003] In a first such transmission right grant during system startup in the data transmission system of the token passing system (generation) method is known following manner. That is, a fixed method in which the first transmission right is fixedly generated for a predetermined specific ECU, transmission is started assuming that each ECU has been granted the first transmission right,
When a collision occurs, transmission is temporarily stopped, and a process of waiting for different waiting times set for each ECU and restarting transmission is repeated until a collision does not occur. There is known a waiting method for converging the transmission right.

[0004]

However, in the fixed system, when a specific ECU that generates the first transmission right breaks down, there is a problem that the transmission right is not generated permanently and the system stops functioning. .

Further, the waiting method has a problem in that it takes time until the first transmission right is generated, and there is a waste of time before it can function as a network.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to provide a vehicular data transmission system capable of quickly generating an initial transmission right and improving data transmission efficiency. is there.

[0007]

In order to achieve the above object, according to the present invention, a plurality of control devices mounted on a vehicle are connected by a network bus, and a transmission right is set between the plurality of control devices. In the vehicle data transmission system for transmitting a message by circulating the data, the plurality of control devices each include a transmission / reception unit for transmitting / receiving data, and a collision detection unit for detecting a collision of transmission data transmitted by the transmission / reception unit. And arbitration means for arbitrating transmission data relating to the collision detected by the collision detection means to avoid collision, and instructing the transmission / reception means to continue / stop data transmission, and managing transmission rights. Management means;
When the transmission right is not generated or lost by the management unit, data transmission is started by the transmission / reception unit, and when the collision of transmission data is not detected by the collision detection unit, or by the arbitration unit. When instructed to continue data transmission, the control device survives and
Control means for continuing transmission of data by the transmission / reception means assuming that the right of trust is maintained; and when the transmission of data continued to be transmitted by the control of the control means is completed, the next control is performed in accordance with a predetermined rule. Delegating means for delegating the transmission right to the device , wherein the arbitration means is configured to transmit
With the logical level of dominant as the dominant logical level and the
Transmission by the transmission / reception means based on the logic of the communication data
Transmitted data and received from the network bus
Compare the data with each other in 1-bit units.
In this case, data transmission is stopped .

[0008] Further , the delegating means includes a predetermined
Increment the destination address representing the controller by one
Transfer of the right of transmission to the next control device.
You may do it.

[0009]

Each of the control means in the plurality of control devices of the present invention causes the transmission / reception means to start data transmission when the management means detects that the transmission right has not been generated or has been lost. As a result, when no collision of the transmission data is detected by the collision detecting means, or when the arbitration means is instructed to continue the data transmission, the control device wins.
The transmission right is maintained and the transmission of the data by the transmission / reception means is continued.

[0010] In this case, the arbitration means, one logic level of the data (e.g., "H" level) dominant, other logic level (e.g., "L" level) on the basis of the logic of the transmission data to be recessive The transmission data transmitted by the transmission / reception means is compared with the data received from the network bus in 1-bit units. If the two data are different, the data transmission is stopped, and if the two data match, the data transmission is continued. Let it.

In other words, when the transmission right is not detected when the system is started, or when the control device that has acquired the transmission right breaks down and the transmission right is lost, each control device transmits its own transmission right. Data transmission starts immediately, assuming that the transmission right has been acquired, and as a result, if no collision occurs, it is assumed that the transmission right has not been generated or the first transmission right after the loss has been detected is actually obtained. Continue sending data. On the other hand, when a collision occurs, in the above example, the control apparatus that transmitted the “H” level bit data transmits the first transmission right after the non-occurrence of the transmission right and the detection of the disappearance are transmitted. Win the first transmission right by winning the right competition. Therefore, when no collision occurs, the control device that has started data transmission can continue data transmission from the beginning, which is the same as when the transmission right is generated in the control device from the beginning. On the other hand, in the event of a collision, the control device that has won the competition to acquire the transmission right can continue data transmission from the beginning in the same manner, which is the same as when the transmission right has occurred in the control device that survived from the beginning. Will be. That is, since there is one control device that can continue data transmission from the beginning when transmission right has not been generated or transmission right has been lost, the delay time of transmission right generation can be eliminated. Therefore, compared to the conventional method in which transmission is temporarily stopped once in the event of a collision, the above-mentioned first transmission right is generated quickly, and there is no useless time until it can function as a network. Also, one logical level of data
Of the transmitted data, where
Transmission data transmitted by the transmission / reception means based on the
And the data received from the network bus
And stop sending if both data are different
And if both data match, continue data transmission
Even if contention occurs between multiple controllers,
Eventually, one control unit wins the race for transmission rights.
Will remain.

Further, the delegating means of the control device which has acquired the first transmission right, when the transmission of the data whose transmission has been continued under the control of the control means is completed, that is, the data transmission based on the acquired transmission right is completed. When finished, prescribed
According to the rule described above , for example , the transmission right is transferred to the next control device by incrementing the destination address representing each control device by one.

[0013] That is, when the stem rising or transmitted first acquired control device after the failed right transmission right, is rapidly generate by competitive method, the subsequent transmission right, token passing not the competition method By circulating between the control devices in a system, each control device is equally given a transmission right.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a vehicle control system according to one embodiment of the present invention. Electronic control devices (hereinafter referred to as “ECUs”) 1 to 5 are connected via a network bus 6. Interconnected. ENG control E
CU1 is an ECU that controls the operation of the engine in accordance with the operation of the accelerator pedal by the driver of the vehicle, a MISS control EC
U2 is an ECU that controls the automatic transmission in accordance with the driving state of the vehicle, TCS control ECU 3 detects a slip state of the drive wheels of the vehicle, and controls the output torque of the engine. The ECU that controls the suspension (active suspension) according to the driving state of the vehicle and the brake control ECU 5 are ECUs that detect the locked state of the wheels and perform the brake control. These ECUs 1 to 5 are connected via a network bus 6 to mutually transmit and receive necessary data because it is necessary to mutually monitor control parameters and operating parameters detected by sensors.

FIG. 2 is a block diagram showing the configuration of the ENG control ECU 1. A central processing unit (hereinafter referred to as "CPU") 101 includes a plurality of sensors 11 and fuel injection valves via an input / output interface 104. It is connected to the actuator 12. The CPU 101 transmits a RAM (Random Access) via the bus line 107.
Memory) 102, ROM (Read Only)
Memory 103 and a communication control IC (Inte
(grated circuit) 105. The communication control IC 105 includes the bus interface 10
6 is connected to the network bus 6.

The CPU 101 determines a control parameter based on the value detected by the sensor 11 according to a program stored in the ROM 103, and drives the actuator 12. The RAM 102 is used for, for example, temporarily storing data being calculated. The communication control IC controls transmission of a message to the network bus and reception of a message from the network bus.

FIG. 3 is a diagram showing a specific configuration of the bus interface 106 and the network bus 6. The network bus 6 is composed of twisted pair wires 6b and 6c terminated by a terminating resistor 6a.

The first transmission terminal of the communication control IC 105 is connected to the base of the transistor 119 via the resistor 115. The emitter of the transistor 119 is connected to the power supply line VSUP, and the collector is connected via a resistor 116 to the inverting input of the comparator 111 and to one twisted pair line 6b.

The second transmission terminal of the communication control IC 105 is connected to the base of the transistor 120 via the resistor 117. The emitter of the transistor 120 is connected to the ground, and the collector is connected via the resistor 118 to the comparator 1.
11 non-inverting inputs and the other twisted pair line 6c.

The non-inverting input of the comparator 111 is connected to the power supply line VSUP via a resistor 112 and also to the inverting input of the comparator 111 via a resistor 113. The inverting input of the comparator 111 is connected to the ground via the resistor 114, and the output of the comparator 111 is connected to the receiving terminal of the communication control IC 105.

In the circuit of FIG. 3, resistors 116 and 11
8 is about 30Ω, resistors 112 and 114 are about 2 kΩ,
The resistance 113 is about 200Ω, and the termination resistance 6a is about 100Ω.

Pulse signals having phases opposite to each other are output to the first and second transmission terminals of the communication control IC, and the first transmission terminal outputs the second transmission signal at a low level (also called low, L, or 0). Terminal is high level (also called high, H or 1),
At this time, both the transistors 119 and 120 are turned on, one twisted pair line 6b is high, and the other twisted pair line 6c is low. When the first transmission terminal is high and the second transmission terminal is low, transistors 119 and 12
0 are both off, and one twisted pair wire 6b is low,
The other twisted pair line 6c becomes high. In this way, a signal is transmitted on the network bus 6.

The output of the comparator 111 changes to low / high in response to the high / low state of one twisted pair line 6b, and the signal on the network bus 6 is received.

The ECUs 2 to 5 are basically configured similarly to the ECU 1. Therefore, if one ECU sends out a signal in which one twisted pair line 6b goes low (6c goes high), and the other ECU sends out a signal going high, the signal on the twisted pair line 6b goes high. Because
In this embodiment, the state in which the twisted pair line 6b is high (6c is low) is dominant (dominant), and the opposite state is recessive (inferior).

Next, a method of data transmission between the ECUs will be described. In this embodiment, the token passing method is adopted in principle. This method can be arbitrated CS
MA / CD (Carrier Sense Multi)
ple Access Collision Dete
Ction) system is advantageous in terms of electrical delay on the bus, and the maximum message delay time is easily obtained, so that the design of the network system is easy.

However, if the transmission right (hereinafter referred to as token) is not detected when the system is started up, or if the control device that has acquired the token breaks down and the transmission right is lost, it is detected. The first later token is configured to be generated according to a predetermined contention scheme. This predetermined competition method will be described later in detail.

FIG. 4 is a diagram showing the format of a message used for data transmission in this embodiment. FIG. 4 (a) shows the format of a data message for transmitting a token and data. (B) shows the format of a token message for transmitting only the token. In the following description, the ECUs 1 to 5 that constitute the network system are called nodes.

In FIG. 4A, the field F1 (S
OM) is a field indicating the start of the message,
The bits consist of dominant bits. All nodes constituting the network system are used for synchronization.

The field F2 (TA) is a 4-bit field indicating the address (token address) of the node at the destination of the token. The node address is, for example, E
Values 0 to 4 are set corresponding to CUs 1 to 5, respectively.

Field F3 (CTL) is a field indicating the type of message (token message or data message).

Field F4 (DATA UNIT)
Is a data unit, and indicates a DN (Destination) indicating an address of a node to receive the message.
(Node Length) field, DLC (Data Length) field indicating the byte length of the DATA field, and ID (Identify) that constitutes an identifier of data.
er) field and DA with information to be transmitted
It consists of a TA field. The DATA field has a variable length as can be inferred from the above description, and the data unit as a whole has a variable length in the range of 32 to 96 bytes.

The field F5 (FCS) is given by the following equation (1)
Consisting of a 16-bit error detection character string (CRC character string) obtained by using
(Cyclic Redundancy Check)
Field. Between fields F5 and F6,
1-bit recessive bit delimiter
Is inserted.

Generator polynomial = X ¹⁶ + X ¹² + X ⁵ (1) Field F6 (DACK) is a field for a node which has normally received data to make a reception acknowledgment (acknowledgment), and is a 2-bit acknowledge. Consists of slots. The transmitting node transmits the acknowledgment slot as recessive bits and is designated as a node to receive,
All of the nodes that have received the data normally make a reception acknowledgment by overwriting the two dominant bits. Between the fields F6 and F7, a 2-bit recessive bit delimiter is inserted.

A field F7 (TACK) is a field for a node that has received a token normally to acknowledge reception, and is made up of a 2-bit acknowledge slot as in the field F6. The transmitting node transmits the acknowledgment slot as a recessive bit, and the node that has received the token performs a reception acknowledgment by overwriting the two dominant bits. Field F
Between 7 and F8, a 2-bit recessive bit delimiter is inserted.

The field F8 (EOM) is a field indicating the end of the message, and is composed of 6 recessive bits.

The token message shown in FIG.
The configuration is such that fields F4 to F6 of the data message are deleted, and a delimiter is inserted between fields F3 and F7.

Next, a token circulation method will be described.

The node that has acquired the token must transfer the token together with the transmission data if it has transmission data, or only the token if there is no transmission data to the next node. The node to which the token is transferred is the node corresponding to the token address indicated in the field F2 (TA) of the message. Normally, the token address is initially set to an address obtained by adding the value 1 to the address of the own node, and the message is transmitted by increasing the token address until an acknowledgment response is obtained. However,
In this embodiment, when the address of the own node is the value 15,
The token address is 0.

When the node corresponding to the token address receives the token, the node responds by overwriting the acknowledge slot in the field F7 (TACK) with two dominant bits. The acknowledgment is overwritten and the message is successfully returned in field F8 (EO
At the point of time up to M), the node that sent the token completes the token transfer, and the receiving node acquires the token.

Next, a method of detecting a transmission failure will be described.

If there is no error during transmission, an acknowledgment is not overwritten in the acknowledgment slot in the field F6 (DACK), or an error is detected during transmission. , The failure is detected at the sending node.

On the other hand, errors detected during transmission include monitoring detection, CRC detection, bit stuff error detection, and message format check detection.

The detection by monitoring is an error when the data transmitted by the transmitting node does not match the data on the bus. However, field F
6, F7 acknowledgment slot followed by 1
Monitoring is prohibited for recessive bits.

Detection by CRC is performed in the field F5 (F
If an error is detected by the CRC character of (CS), it is regarded as an error, and is performed by a node other than the transmitting node.

A bit stuff error is an error when the same logic is detected continuously for more than 5 bits, and is detected by a node other than the transmitting node. However, fields F6 (DACK), F7 (TA
CK), F8 (EOM) and delimiter are excluded from the detection target.

The detection by the message format check is an error when an illegal logic occurs in the fixed bit field (F3, F8, delimiter), and is detected by a node other than the transmission node.

When the above-described error during transmission is detected, an error message (6 dominant bits) is immediately transmitted from the detected node. Therefore,
Even when an error is detected in a node other than the transmission node, the transmission node can recognize occurrence of the error.

Next, a description will be given of the first token generation operation when no token is generated or lost, with reference to the flowchart of FIG. 5 and the time chart of FIG.

Communication control IC of each of ECUs 1 to 5 (node)
105, first, determines whether or not the network bus 6 is in an idle state to determine whether or not a token has not been generated at system startup or a token has been lost due to a failure of a node related to token acquisition. It is determined (step S1 in FIG. 5). As a result, if it is not in the idle state, that is, if the other ECU is in the transmission state, this flow ends.

On the other hand, if the network bus 6 is in the idle state, that is, if the other ECU is not in the transmission state, it is assumed that the own node has acquired the token, and the communication control I
Data transmission is started via C105 and the bus interface 106 (step S2). Then, the transmission data and the data on the network bus 6 are compared on a bit-by-bit basis, and it is determined whether or not both data match (step S3). As a result, the transmission data and the network bus 6
If the data above matches, it means that there is no conflict with the data transmitted from the other node, or that the node has won the token acquisition competition even if there is a conflict as described later. Therefore, the data transmission is continued assuming that the token has not been lost. That is, it is determined whether or not the series of data being transmitted has been transmitted (step S4). If the series of data being transmitted has not been transmitted, the process returns to step S3 to return to the bit data associated with the next transmission. Perform the same processing.

It is needless to say that a conflict occurs when the same processing is performed as described above, and the data transmission may be stopped this time, losing the token acquisition competition. In addition, as a method for determining the coincidence between the transmission data and the data on the network bus 6 in step S3, a method is employed in which when an error is detected by monitoring error detection, it is determined that they do not match. In this case, specifically, the coincidence is determined by taking an exclusive OR of the transmission data and the reception data from the network bus 6.

On the other hand, if the transmission data and the data on the network bus 6 are different, a conflict with data transmitted from another node occurs, which means that the own node has lost the token acquisition competition. , Transmission is stopped (step S5), and this flow is terminated.

In step S4, when it is determined that the series of data being transmitted has been transmitted, that is, when the token acquisition competition has been completed to the end, it is determined whether or not the token transfer has been completed. (Step S6) If the transfer is not completed, the token address is incremented by "1" and a token message is sent to the network bus 6 (Step S7). The process of S7 is executed, and the flow ends when the transfer of the token is completed.

In order to prevent the determination from being made incorrectly due to noise or the like when determining a conflict, the same bit data is actually transmitted a plurality of times.

Next, a specific example of the conflict determination processing in steps S3 to S5 will be described with reference to the time chart of FIG.

Now, it is assumed that data is transmitted from the node 1 and the node 2 as shown in FIG.
As described in paragraph [0026], the logic level “1” is the dominant bit, the logic level “0” is the recessive bit, and a collision occurs between the logic level “1” and the bit at the “0”. When this occurs, the logical level on the network bus 6 becomes "1".

In the case of FIG. 6, data of the same logical level is transmitted to the nodes 1 and 2 from the 1st bit to the 4th bit.
Since the logical levels of the data above match, nodes 1, 2
Continue data transmission from the first bit to the fourth bit.

However, at the fifth bit, the logical level of node 1 is "1" and the logical level of node 2 is "0". At the fifth bit, the logical level on the network bus 6 becomes the dominant bit “1”. Then, the node 1 that has transmitted the dominant bit of the logic level “1” continues the transmission as if the token has not been lost, and the node 2 that has transmitted the recessive bit of the logic level “0” has the token that has lost the token. To stop sending.

FIG. 6 shows an example of a conflict between two nodes. However, actually, a conflict may occur between three or more nodes. However, since it is impossible for these nodes to keep transmitting exactly the same data, one node always ends up in the token acquisition competition, and no trouble occurs.

As is apparent from the above description, according to the present embodiment, when the system is started or when a node related to token acquisition fails, the first subsequent token is generated in a competitive manner. Makes the token rotate. As a result, a token can be generated quickly, and all nodes can acquire the token equally, so that the system can function efficiently.

The present invention is not limited to the above embodiment. For example, as a method of arbitration when a data collision occurs, the logic level “0” is dominant and the logic level “1” is It is possible to arbitrate as recessive. In addition, when the first token is generated by the competition method and the token is circulated, the first token transfer destination node does not need to be the node of the node address next to the node that acquired the first token in the competition method. Delegate to a predetermined node such as the node with the youngest node address,
Thereafter, the nodes may be circulated in a fixed circulation cycle.

[0063]

As described above, according to the vehicular data transmission system according to the present invention, the transmission right is not generated or the transmission right is not generated, such as when the system starts up or when the node related to token acquisition fails. When the loss of the right is detected, there is one control device capable of continuing the data transmission from the beginning, so that the delay time of the generation of the transmission right can be eliminated. Therefore, compared to the conventional method in which transmission is temporarily stopped once in the event of a collision, the above-mentioned first transmission right is generated quickly, and there is no useless time until it can function as a network.
Moreover, the subsequent first token is generated in a competitive manner, and thereafter, the token is circulated. Therefore, the token can be generated quickly, and all nodes can acquire the token equally, so that the system can function efficiently. In addition, multiple systems
Even if a conflict occurs between control devices, one control
To ensure that your device survives the race for transmission rights.
it can.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a schematic configuration of a vehicle control system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an electronic control device in FIG.

FIG. 3 is a diagram showing a specific configuration of a bus interface in FIG. 2;

FIG. 4 is a diagram showing a configuration of a message transmitted and received between electronic control devices.

FIG. 5 is a flowchart showing an initial token generation operation when a token is not generated or lost.

FIG. 6 is a time chart for explaining a method of arbitration when a conflict occurs.

[Explanation of symbols]

 1: Engine control electronic control unit 6: Network bus 101: Central processing unit (CPU) 105: Communication control IC 106: Bus interface

Claims (2)

(57) [Claims] 1. A vehicle data transmission system for transmitting a message by connecting a plurality of control devices mounted on a vehicle via a network bus and circulating a transmission right between the plurality of control devices. A control unit for transmitting and receiving data; a collision detecting unit for detecting a collision of transmission data transmitted by the transmitting and receiving unit; and a collision detecting unit for detecting a collision of the transmission data related to the collision detected by the collision detecting unit. Arbitration means for performing arbitration for avoidance and instructing the transmission / reception means to continue / stop data transmission; management means for managing transmission rights; and detection of non-occurrence or loss of transmission rights by the management means. The data transmission is started by the transmission / reception means, and when the collision of the transmission data is not detected by the collision detection means, or Serial The controller surviving when instructed to continue the data transmission by the arbitration means, feed
Control means for continuing transmission of data by the transmission / reception means assuming that the right of trust is maintained; and when transmission of data whose transmission has been continued under the control of the control means is completed, the next control is performed in accordance with a predetermined rule. Delegating means for delegating the transmission right to the device , wherein the arbitration means sets one logical level of data to dominant,
Based on the logic of the transmitted data that makes the other logic level recessive
The transmission data transmitted by the transmitting / receiving means and
Data received from the network bus in 1-bit units
If the two data are different, stop data transmission.
A data transmission system for a vehicle, comprising: 2. The transfer device according to claim 1, wherein the transfer unit transfers the transmission right to the next control device by incrementing a predetermined destination address representing each control device by one. serial mounting vehicle for data transmission system.