JP2947437B2 - Data transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission method for transmitting and receiving messages via a common communication line interconnecting a plurality of electronic control units mounted on a vehicle such as an automobile.

[0002]

2. Description of the Related Art When 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") and data are mutually transmitted, each of the ECs is required.
The transmission right is circulated between U in a predetermined order, and the transmission right is obtained.
A method (token passing method) that allows only a CU to send data to a network bus has been conventionally known.

[0003] In such a data transmission system of the token passing system, there is known a system for adding broadcast data to a message for transmission right transmission and transmitting the message (Japanese Patent Publication No. 1-58900).

[0004]

However, in the above-mentioned conventional system, a message structure is adopted which allows the transmission side to immediately confirm whether the transfer of the transmission right and the transmission of the data have been correctly performed. Therefore, there is still room for improvement in promptly performing the transmission process.

The present invention has been made in view of this point, so that the success or failure of transmission right transfer and data transmission can be quickly confirmed, and the transmission right can be smoothly circulated. It is an object of the present invention to provide a data transmission method.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention circulates a transmission right between a plurality of control devices mounted on a vehicle and connected by at least one common signal line to transmit a message. In the data transmission method for transmitting and receiving, the message includes a first response field in which the control device that has received the transmission right writes a first acknowledgment indicating the reception of the transmission right; A second acknowledgment field for writing a second acknowledgment indicating successful reception, and waiting or continuing until the next transmission right is obtained according to the contents of the first and second acknowledgment fields.
In response to the first acknowledgment,
The corresponding process is a process of retransmitting data,
The processing is executed prior to the processing when there is no second acknowledgment .

[0007]

[0008]

Further, the present invention relates to a data transmission method for transmitting / receiving a message by circulating a transmission right between a plurality of control devices mounted on a vehicle and connected by at least one common signal line, wherein the message is A first message for transmission right transfer having a first response field for writing a first acknowledgment output by the control device having received the transmission right, and a control device receiving the first response field and the data There has a <br/> second response field which second writing an acknowledgment to be output consists of a second message for performing transmission of the transmission right transfer and data, each of said control device, said first When the first acknowledgment is obtained by sending the message No. 2, it is determined that the transfer of the transmission right has been completed regardless of the presence or absence of the second acknowledgment, and the next transmission is performed. It does not transmit until a, when said first acknowledgment has not been obtained, is obtained so as to send the first message to continue delegating processing of the transmission right.

[0010]

According to the method of the first aspect, a first acknowledgment indicating the reception of the transmission right is written in the first response field by the control device that has received the transmission right, and the control device that has received the data writes the first acknowledgment in the first response field. A second acknowledgment indicating successful data reception is written in a second response field, and the transfer of the transmission right between the control devices and the retransmission of data are performed according to the contents of the first and second response fields. Is performed. Sand
That is, the processing corresponding to the first acknowledgment is performed by the second
The process is executed prior to the process when there is no positive response. What
The processing corresponding to the first acknowledgment is the next transmission right.
In the waiting or continuous delegation of transmission rights
The processing when there is no second acknowledgment is
This is the process of performing retransmission.

[0011]

According to the method of claim 4, a first message for delegation of transmission having a first response field and a delegation of transmission and transmission of data having first and second response fields. And a second message is sent by the first controller to send a second message to obtain a first acknowledgment.
Regardless of the presence or absence of the second acknowledgment, transmission is not performed until the next transmission right is obtained. Also, when one controller sends out the second message and fails to obtain the first acknowledgment,
The one control device performs a first operation to continue the transmission right transfer process.
Is sent out.

[0013]

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

FIG. 1 is an overall configuration diagram of a vehicle control system according to an embodiment of the present invention.
1 to 5 are mutually connected via a network bus 6. The ENG control ECU 1 controls the operation of the engine according to the accelerator pedal operation of the driver of the vehicle. The MISS control ECU 2 controls the automatic transmission according to the driving state of the vehicle. The TCS control ECU 3 controls the automatic transmission. An ECU that detects the slip state of the driving wheels of the vehicle and controls the output torque of the engine, and a suspension control ECU 4 controls the suspension (active suspension) according to the driving state of the vehicle.
U, the brake control ECU 5 is an ECU that detects the locked state of the wheels and performs brake control. These ECUs 1
5 to 5 need to mutually monitor control parameters and operating parameters detected by sensors, and are connected via a network bus 6 to mutually transmit and receive necessary data.

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 actuators 12 such as fuel injection valves via an input / output interface 104.
It is connected to the. The CPU 101 has a bus line 107
(Random Access Memory) 102 via the
M (Read Only Memory) 103 and a communication control IC (Inte
grated Circuit) 105. Communication control I
C105 is connected to the network bus 6 via the bus interface 106.

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 includes 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 line V
SUP, and the collector is connected via the resistor 116 to the inverting input of the comparator 111 and one of the twisted pair lines 6.
b.

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 a resistor 118 to the comparator 11.
One non-inverting input and the other twisted pair line 6c.

The non-inverting input of the comparator 111 is a resistor 1
The power supply line VSUP is connected to the power supply line VSUP via the reference numeral 12 and also connected to the inverting input of the comparator 111 via the resistor 113. The inverting input of the comparator 111 is connected to ground via a resistor 114, and the comparator 1
The output of 11 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. The first transmission terminal is at a low level (low) and the second transmission terminal is at a high level (high). 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, the transistors 119 and 120 are both turned off, and one twisted pair line 6b is low and the other twisted pair line 6c is 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 high / low of one twisted pair line 6b, and a 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, a token passing method is adopted. This method is arbitrated CSMA / CD
(Carrier Sense Multiple Access / Collision Detecti
This method is advantageous in that it is advantageous in terms of electrical delay on the bus as compared with the (on) method, and that the maximum message delay time is easily obtained, thereby facilitating the design of a network system.

FIG. 4 is a diagram showing the format of a message used for data transmission in this embodiment. FIG. 4A shows the format of a data message (second message) for transmitting a token and data. FIG. 2B shows the format of a token message (first 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 token destination node. 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).

A field F4 (DATA UNIT) is a data unit, and is a DN (Destination) indicating an address of a node to receive data of the DATA field.
It comprises a Node field, a DLC (Data Length) field indicating the byte length of the DATA field, an ID (Identifier) field constituting a data identifier, and a DATA field having information to be transmitted.

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. A 1-bit recessive bit delimiter (separator) is inserted between the fields F5 and F6.

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

A field F7 (TACK) is a field (first response field) for a node that has normally received the token to make a reception acknowledgment (first acknowledgment), and is a 2-bit field like the field F6. Consists of an acknowledgment slot. 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. Fields F7 and F8
Between them, a two-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.

By providing the field F7 for the token and the field F6 for the data as fields for confirming reception, it is possible to quickly confirm the success or failure of each of the transfer of the token and the transmission of the data. Becomes

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, it responds with an acknowledgment by overwriting the acknowledge slot in 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, the processing when one node sends a data message and there is no acknowledgment will be described. In the following description, the first acknowledgment overwritten in the field F7 is the token ACK, the field F6.
Is referred to as data ACK.

(1) There is no token ACK and the data AC
If K is found The token address is incremented by 1 and a token message is sent. This is for transferring the token only to the next node after the previous failed node because the reception confirmation was obtained for the data in the field F4.

(2) There is a token ACK and the data AC
When there is no K Since the transfer of the token has been completed, the data is not retransmitted. If possible at the next token acquisition, retransmit the data.

(3) When neither the token ACK nor the data ACK is present The token address is incremented by 1, the token message is transmitted, and the data is not retransmitted.
Thereby, the circulation of the token is prioritized over the transmission of the data, and the circulation of the token can be performed more smoothly. If possible at the next token acquisition, the data is retransmitted.

As described above, if there is a token ACK even if there is no data ACK, it is determined that token transfer has been completed, data retransmission is not performed, and if there is no data ACK and token ACK, token transfer processing Since only the retransmission is performed and the data is not retransmitted, the token can be smoothly circulated. The reason why the transfer of the token is prioritized is that when one node repeats retransmission of data, the maximum delay time of the system becomes longer than when the transfer of the token is prioritized. .

In the above-described embodiment, the token ACK
If the data ACK and the data ACK do not exist, the token message is immediately transmitted and the data is not retransmitted. However, the present invention is not limited to this.
The token transfer process may be performed after retransmitting the data about twice. FIG. 5 is a flowchart showing a control procedure of the communication control IC 105 in this case when transmission is completed (when an error message is generated or when message transmission is completed).

In the following description, an error during transmission is detected by the transmitting node or the receiving node, and when detected, the error message is transmitted from the node where the error message is detected, and the transmission ends.

In step S1 of FIG. 5, it is determined whether or not an error has occurred during transmission, and if not, it is determined whether or not token transfer has been completed (whether or not a TACK has occurred) (step S1). S2). As a result, when the transfer of the token is completed, the first and second counters CT1 and CT2 described later are reset (step S1).
0), this process ends. If no error has occurred during transmission, but the transfer of the token has not been completed, the process proceeds to step S3 to determine whether the data transmission was successful (D
ACK is detected). As a result, when the data transmission is successful, a token transfer process is performed (step S9), and the first and second counters CT1, C1
T2 is reset (step S10), and this processing ends.

If the answer to step S3 is negative (NO), that is, if no error occurred during transmission, but token transfer and data transmission failed (acknowledgement response TACK, DA
If there is no CK), the process proceeds to step S4, and the first
Is incremented by one, and it is determined whether or not the count value is equal to a first predetermined value C1 (for example, 2) (step S5). At first, since CT1 <C1, retransmission processing of the message for which transmission failed is performed (step S8), and this processing ends. After that, there is no confirmation response, and when CT1 = C1, the process proceeds from step S5 to step S9, where the token is transferred to another node to reset the counters CT1 and CT2 (step S1).
0), this process ends.

If the answer to step S1 is affirmative (YES), that is, if an error has occurred during transmission, the second counter C
T2 is incremented by 1 (step S6), and it is determined whether or not the count value is equal to a second predetermined value C2 (for example, 5) larger than the first predetermined value C1 (step S7). At first, since CT2 <C2, retransmission processing of a message that failed to be transmitted is performed (step S8), and this processing ends. After that, an error occurred during transmission,
When CT2 = C2, steps S9 and S10 are executed, and the process ends.

According to the processing shown in FIG. 5, if transmission fails, retransmission is performed at most (C1-1) times when there is no acknowledgment, and at most (C1-1) when an error occurs during transmission.
2-1) The retransmission is performed only once, and if the transmission still fails, the token is transferred to another node.

Here, since C2> C1, the maximum number of retransmissions is larger in the case of an error during transmission than in the case of no acknowledgment. This is because if there is no acknowledgment, there is a high possibility that the node to be received does not exist, and it is highly likely that the node will fail even if retransmission is performed. This is because the possibility of success in retransmission due to the change is considered.

If the failure continues, the token is transferred to another node so that the token can be smoothly circulated.

[0053]

As described above in detail, according to the data transmission method of the first aspect, the control device that has received the transmission right writes the first acknowledgment indicating the reception of the transmission right in the first response field. A second acknowledgment indicating successful data reception is written in the second response field by the control device that has received the data, and until the next transmission right is obtained according to the contents of the first and second response fields. Wait or continue
Corresponding to the first acknowledgment, which is a transfer right transfer process
The process of retransmitting data.
2 is executed prior to the processing when there is no acknowledgment, so that the success or failure of each of the transfer of the transmission right and the transmission of the data can be quickly confirmed , and the data can be confirmed.
Of transmission rights takes precedence over transmission of data,
It can be performed more smoothly .

[0054]

According to the data transmission method of the present invention, a first message for transmitting a transmission right having a first response field, and a transmission right delegation having first and second response fields. And a second message for transmitting the data is used, and when one controller sends out the second message and obtains the first acknowledgment,
The one control device does not transmit until the next transmission right is obtained, regardless of the presence or absence of the second acknowledgment, and the one control device sends the second message to obtain the first acknowledgment. If not, the one control device sends the first message to continue the transmission right transfer process, so that the transmission right can be smoothly circulated.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of an electronic control device that configures the system of FIG. 1;

FIG. 3 is a diagram showing a specific configuration of a bus interface of 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 a processing procedure when data transmission is completed.

[Explanation of symbols]

 DESCRIPTION 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 data transmission method for transmitting and receiving a message by circulating a transmission right between a plurality of control devices mounted on a vehicle and connected by at least one common signal line, wherein the message has a transmission right. A first response field in which the receiving control device writes a first acknowledgment indicating receipt of the transmission right, and a second response field in which the control device receiving the data writes a second acknowledgment indicating successful reception of the data A response field, and depending on the contents of the first and second response fields , waiting until the next transmission right is obtained or
The first acknowledgment, which is continuous transmission right transfer processing.
Is a process of retransmitting data.
Execute in precedence over processing when there is no second acknowledgment
A data transmission method. 2. A data transmission method for transmitting / receiving a message by circulating a transmission right between a plurality of control devices mounted on a vehicle and connected by at least one common signal line, wherein the message has a transmission right A first message for delegation of transmission having a first response field for writing a first acknowledgment output by the control device receiving the first acknowledgment;
A second message for transferring the transmission right and transmitting data, the second message having a first response field and a second response field for writing a second acknowledgment output by the control device that has received the data; When each of the control devices transmits the second message and obtains the first acknowledgment, it determines that the transfer of the transmission right has been completed regardless of the presence or absence of the second acknowledgment. The transmission is not performed until the next transmission right is obtained, and when the first acknowledgment is not obtained, the first message is transmitted to continue the transmission right delegation process. Data transmission method.