JPH11177590A - Multiplex communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce data quantity to be transmitted/received between nodes in a multiplex communication system where the plural nodes mutually execute communication. SOLUTION: When it is supposed that the ON and OFF of a switch is respectively indicated by the '1' and '0' of flag data for example, the inversion of a switch state at every frame transmission timing such as ON, OFF, ON, OFF to ON... cannot occur in actual control, so that it is reported that flag data is invalid at the time of executing transmission with a pattern like '10101'. A corresponding flag data string in plural continuous frames having the same frame ID is adopted as a specified invalid pattern '10101'. Therefore, change is executed by '1' in a first time, '0' in the second time, '1' in the third time, '0' in the fourth time and '1' in the fifth time when a certain kind of flag data in the first time transmission frame F is the invalid one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex communication system in which a plurality of nodes transmit and receive data to and from each other via a communication line.

[0002]

2. Description of the Related Art In recent years, for example, the number of electrical components and electrical devices mounted on automobiles has been steadily increasing with the advancement of functions and performance of vehicles, and wiring within the vehicles is complicated and large. It is getting bigger. Therefore, as a means for solving such a problem, a multiplex communication system in which a plurality of devices are connected to each other by a communication line to perform communication between the devices has been put to practical use.

[0003] In such a multiplex communication system, flag data is transmitted and received in addition to 1-byte data and 2-byte data. For example, it is used for notifying the control state that the cruise control device is currently performing cruise control to another control device, or when giving a command from one control device to another control device. One-bit data is sufficient as such flag data.

[0004]

However, the conventional multiplex communication system has a problem in communication when transmission data is invalid. Here, the “transmission data is invalid” here means, for example, a case where the data itself has not been determined or a case where a sensor or the like necessary for data determination has an abnormality and the data cannot be determined.

If the transmission data is data in units of 1 byte or data in units of 2 bytes, a specific area including substantial data is secured in the data area, and valid / invalid data outside the specific area is reserved. For example, a method of adding data indicating the presence of the information may be employed. On the other hand,
In the case of 1-bit flag data, the method itself of dividing the data area cannot be adopted. For this reason, for example, a scheme has been devised to secure another flag data area indicating whether the flag data is valid or invalid for each flag data. However, in this case, two bits are required to exchange 1-bit flag data. In other words, it is necessary to transmit and receive twice the data amount of the originally required flag data.

Recently, in such a multiplex communication system,
Although the amount of data transmitted / received between a plurality of control devices is increasing, and this is addressed by improving the communication rate, it is desired to reduce the amount of data transmitted / received for an essential solution. The present invention has been made in view of such a problem, and has as its object to reduce the amount of data transmitted and received between nodes in a multiplex communication system in which a plurality of nodes communicate with each other.

[0007]

In the multiplex communication system according to the first aspect of the present invention which has been made to achieve the above object, when each node has invalid flag data to be transmitted, Transmission control means for transmitting a frame by changing a corresponding flag data string in a plurality of consecutive frames having the same frame ID so as to have a specific invalid pattern; Invalidity determining means for determining whether or not the corresponding flag data string is the specific invalid pattern.

[0008] "Flag data to be transmitted is invalid"
This means that the flag data itself has not been determined, or there is an abnormality in a sensor or the like necessary for determining the flag data, and the flag data cannot be determined. If the flag data to be transmitted is invalid, it must be distinguished from the case where the flag data is valid in some way. Conventionally, as a technique for distinguishing the flag data, for example, a method of securing another flag data area indicating whether the data is valid or invalid corresponding to each flag data has been considered as described above. However, in this case, two bits are required to exchange 1-bit flag data.

On the other hand, in the case of the multiplex communication system of the present invention, the corresponding flag data string in a plurality of consecutive frames having the same frame ID is changed so as to have a specific invalid pattern. That is, instead of preparing data indicating valid / invalid separately from the flag data as in the related art, the flag data itself is used to the last. Although we have no separate data like this,
It is considered in units of "flag data string", and the arrangement is changed to a specific invalid pattern to notify the invalidity. On the receiving side, the same frame ID
It is only necessary to determine whether or not the corresponding flag data sequence in a plurality of consecutive frames having a specific invalid pattern. Therefore, the amount of data to be transmitted can be reduced as compared with the conventional case, which is very effective.

[0010] Note that the limitation such as "having the same frame ID ..." is that in general frame transmission, not only one type of frame is continuously transmitted, but a plurality of types of frames are transmitted. This is because they are mixed and transmitted. That is, since the frame ID is included to distinguish the frames, the target flag data is included in the frame having the same frame ID.

Although various "specific invalid patterns" can be considered as the above, for example, a pattern in which the state in which the flag data is inverted every time is continued for a predetermined number of times or more can be used. This is, for example, switch ON / OF
Considering that F is indicated by “1” and “0” of the flag data, the state of the switch is inverted every time the frame is transmitted, such as ON → OFF → ON → OFF → ON. Since this can hardly occur from the actual control, when transmitted in a pattern such as “10101”, it can be determined that the flag data is invalid.

The specific invalid pattern is not limited to a pattern in which the flag data is inverted every time, and may be a pattern that is not a periodic inversion, such as "110110010...". This is in consideration of the possibility that the pattern such as “10101” may be caused by so-called noise. Since such non-periodic inversion does not occur due to noise or the like, a more appropriate pattern It can be said that.

On the other hand, a "specific invalid pattern" may be set based on a rule for transmission and reception between nodes, instead of a pattern that cannot occur in such control. For example, if the flag data is valid, the same data is transmitted continuously, and the receiving side sets a rule that the received flag data is valid only when the same flag data is received twice consecutively. is there. That is, the flag data is determined as “1” when the data is continuously received as “11”, and the flag data is determined as “0” when the data is continuously received as “00”.
By doing so, if the same data is transmitted and received in a state where the same data is not continuous such as "10" or "01",
It can be notified that the flag data is invalid. Of course, other various arrangements are conceivable, and a pattern not included in the arrangement may be set as the “specific invalid pattern” described above.

When the flag data is valid as described above, the same data is transmitted continuously. On the receiving side, the received flag data is regarded as valid only when the same flag data is received twice consecutively. It is more preferable that the following considerations be taken into consideration when making the agreement. That is, the transmission cycle of the flag data, that is, the transmission cycle of frames having the same frame ID is set to be equal to or less than half of the shortest cycle for changing the content of the flag data (hereinafter, referred to as the shortest data change cycle). . The flag data indicates the ON / OFF state of the switch connected to the node, for example, 10 m
If the configuration is such that the state is detected every s and ON or OFF is updated, then 10 ms is the shortest data change cycle. Therefore, in this case, the transmission period of the flag data, that is, the transmission period of the frame having the same frame ID is set to 5 ms or less (which is 1/2 of 10 ms). In this way, when the flag data switches from the valid state to the invalid state, the receiving side maintains the previous valid state flag data until it determines that the received flag data is invalid. Can be kept. Therefore, the inconvenience of performing some processing based on invalid flag data can be avoided.

Note that the above-mentioned “invalid pattern that cannot occur in control” and the “invalid pattern set based on the rules for transmission and reception between nodes” are not necessarily alternatives. It may have properties. For example, “10101” as an example of an invalid pattern that cannot occur from the actual control described above is
A case where a state in which the same data is not continuous, such as “10” or “01”, is regarded as an invalid pattern based on an agreement for transmission and reception between nodes also corresponds to a “specific invalid pattern”.

Further, as set forth in claim 4, claim 1 is
In the multiplex communication system according to any one of the above-described items, each of the nodes further includes a predetermined normal based on the received valid flag data when the invalidity determining unit determines that the flag data string is not an invalid pattern. Perform the time processing,
On the other hand, when it is determined that the flag data string is an invalid pattern, a processing execution unit for executing a predetermined abnormal-time process that does not use the received invalid flag data may be provided.

With this configuration, when invalid flag data is received, a predetermined abnormal-time process that does not use flag data is executed instead of a normal-time process that is executed based on valid flag data. Execution of appropriate processing can be prevented. The system according to claim 5 is:
The multiplex communication system according to any one of claims 1 to 4, wherein each node is configured as a control device for controlling each part of the vehicle.

That is, as described above, according to the multiplex communication system according to the first to fourth aspects, even if there is no separate data indicating validity / invalidity, the validity / invalidity is obtained using only the flag data.
The configuration is also configured to notify that the data is invalid, and the data amount at the time of transmission / reception can be reduced. In claim 5, for example, an engine control device, an automatic transmission control device,
It is applied as a control system of a vehicle equipped with a plurality of control devices such as a BS control device and a vehicle control device, but in the case of these control devices, not only processing in parallel, but also Real-time performance is often required due to the characteristics of the control system. Therefore, high-speed data transmission / reception between the control devices is required. Therefore, reducing the amount of data to be transmitted / received is advantageous in terms of improving the speed of data transmission / reception.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. It is needless to say that the embodiments of the present invention are not limited to the following examples, and can take various forms as long as they belong to the technical scope of the present invention.

FIG. 1 shows a multiplex communication system 1 according to an embodiment.
FIG. 3 is a configuration diagram illustrating the configuration of FIG. As shown in FIG. 1, the multiplex communication system 1 of the present embodiment has four nodes.
That is, a control device for controlling the engine (hereinafter, referred to as a control device)
An engine ECU) 10 and a control device (hereinafter, referred to as an “anti-lock brake system”) (ABS)
ABS-ECU) 20, a control device for controlling the transmission (hereinafter, referred to as ECT-ECU) 30, and a control device for performing vehicle control (hereinafter, referred to as vehicle ECU) 40, four control devices 10 , 2
0, 30, and 40 are four nodes. These four control devices 10, 20, 30, and 40 are connected via a multiplex communication line (hereinafter referred to as a communication line) 50,
They are configured to perform serial communication with each other.

Here, the engine ECU 10 detects a water temperature sensor 11 for detecting a cooling water temperature of the engine (hereinafter, simply referred to as engine water temperature) and a number of revolutions per predetermined time of the engine (hereinafter, simply referred to as engine speed). The operation state of the vehicle is detected based on detection signals from various sensors such as an engine speed sensor 12 for performing the operation. Based on the detection result, the engine is driven by driving an injector 13 that injects fuel into the engine, an ignition device 14 that induces a high voltage in an ignition coil of the engine to generate an ignition spark in a spark plug, and the like. Control to optimal operating conditions.

The ABS-ECU 20 detects a wheel slip state based on a detection signal from a wheel speed sensor 21 for detecting a rotation speed of the wheel. And
By driving the brake actuator 22 and the like corresponding to each wheel based on the detection result, the slip state of the wheel is controlled to an appropriate state.

On the other hand, the ECT-ECU 30 performs a shift operation based on detection signals from a shift lever switch 31 for detecting a shift lever position and a neutral switch 32 for detecting whether the shift position of the transmission is in the N or P range. By driving the actuator 33, the shift speed of the transmission is controlled.

Further, the vehicle ECU 40 has a throttle opening sensor 41 for detecting the opening of the throttle valve, an idle switch 42 for detecting whether the throttle valve is at a predetermined idle position, and whether the brake pedal is depressed. And a detection signal from a gradient sensor 44 for detecting the gradient of the traveling road. For example, according to data representing the engine speed, the engine water temperature, and the like transmitted from the engine ECU 10, the corresponding meter indicators 45 and the like are driven.

Each of the above-described ECUs 10, 20, 30, 4
0, each has an internal configuration as shown in FIG. That is, each of the ECUs 10, 20, 30, 40 has a CP
It has a one-chip microcomputer (hereinafter simply referred to as a CPU) 60 composed of U, ROM, RAM and the like, and has an input interface 62 and an output interface 64 connected to the CPU 60 via a bus 66. Note that the CPU 60 includes a memory (for example, a storage medium such as a backup RAM) 60a that can retain data even after power is turned off, as one of memories for storing a control program and temporarily storing operation data. .

A water temperature sensor 11 and an engine speed sensor 12 are connected to the input interface 62 in the case of the engine ECU 10 shown in FIG. 1, for example, and detection signals taken from the sensors 11 and 12 are input to the CPU 60. I do. The same applies to the ABS-ECU 20, the ECT-ECU 30, and the vehicle ECU 40.

The output interface 64 is connected to, for example, the injector 13 and the ignition device 14 in the case of the engine ECU 10 shown in FIG. ABS-E
The same applies to the CU 20, the ECT-ECU 30, and the vehicle ECU 40. Then, the CPU 60 calculates various detection data (engine speed, water temperature, etc.) based on detection signals from sensors and switches input via the input interface 62 and controls the drive of the actuator group. Data representing the amount (fuel injection amount,
The ignition timing is calculated, and a control signal corresponding to the calculated data is output to the actuator group via the output interface 64.

Each of the ECUs 10, 20, 30, 40
Is provided with a communication control circuit 70 as communication means for performing mutual data communication via the communication line 50. The communication control circuit 70 includes a transmission memory 70a for storing the transmission data transferred from the CPU 60 and, for example, the engine ECU 1
If it is 0, it is transmitted from the other ECUs 20, 30, 40,
A receiving memory 70b for storing received data received.

For example, the engine ECU 10 will be described.
Various control data to be transmitted to 40 are transmitted data.
The data received from the other ECUs 20, 30, and 40 received by the communication control circuit 70 and stored in the reception memory 70b is stored in the transmission memory 70a via the data transfer line 72, and is transmitted to the data transfer line 72. Ingest through
Using the received data as one of the control data,
Used for calculation of control amount. The communication control circuit 70
Transmits the transmission data stored in the transmission memory 70a to the other ECUs 20 and 3 according to a preset communication protocol.
0, 40 and the other ECUs 20, 30, 4
The transmission data is received from 0 and the received data is stored in the reception memory 70b.

Data is transmitted and received between the ECUs 10, 20, 30, and 40 for each frame F.
Has an SD (Start Delimiter) code, a priority code, a frame ID code, data, and a checksum code, as shown in FIG.
Each of these codes will be described briefly.

First, the SD code is a specific code indicating the start of the frame F, and is used for the ECUs 10, 20, 30, and 4.
At 0, when the SD code is received, the start of the frame F is recognized. Further, the priority code is a code used for priority control, and the plurality of ECUs 10 and
Reference numerals 20, 30, and 40 indicate the priorities for transmitting data and indicating which signal is to be transmitted preferentially when data collide with each other. When a collision of a plurality of data occurs, data with a higher priority is transmitted first.

The frame ID code is a code for identifying what data of each bit of the data area is allocated to the frame, and so-called what kind of data is combined to form the data area. It is shown. The ECUs 10, 20, 30, and 40 can identify the data content in the data area of the transmitted frame based on the frame ID code.

In the data area, 1-byte data and 1-bit flag data can be written. One byte of the flag data area is secured, and as a result, eight flag data can be written. The checksum code is an error detection code transmitted subsequent to the data. ECUs 10, 20, 30, 40
By checking this checksum code, it is possible to know that the frame is at the end. In addition,
For the purpose of ensuring data transmission, an error correction function may be added. That is, the received frame content is checked for errors using the checksum code, and if there is no error, after a certain time within a predetermined time,
The own station address is transmitted to the communication line 50 as a reception confirmation signal (ACK signal). Then, the EC that transmitted the frame F
U10, 20, 30, and 40 receive the ACK signal and recognize that the data has been normally received on the receiving side. When data is not received correctly on the receiving side (when an error is detected by the checksum code)
Alternatively, in the case of a framing error (when the data actually transmitted is shorter or longer than the length specified by the data length), the ACK signal is not returned from the receiving side. In this case, if the ACK signal is not returned within a predetermined time after the end of frame transmission, the transmission side starts retransmission of frame F.

Up to now, the role of the code constituting the frame F has been described. Next, the contents included in the data area will be described with a specific example. FIG.
(A) is an example of a frame transmitted from the vehicle ECU 40, and 1-byte data includes a stroll opening calculated based on a detection signal from the throttle opening sensor 41 and the like. The flag data includes the state of the idle switch based on the detection signal from the idle switch 42, that is, whether the idle switch is ON or OFF. Further, in this embodiment, the vehicle ECU 40 is configured to shut down the power supply of the entire system including the other ECUs 10, 20, 30. Therefore, the power supply shutdown warning is also included as the flag data.

FIG. 3B shows an example of a frame transmitted from the ECT-ECU 30. As the flag data, the state of the neutral switch based on the detection signal from the neutral switch 32, that is, whether the neutral switch is ON or not. OFF is included. Also, flag data indicating whether or not the transmission is shifting through the shift actuator 33 is included.

FIG. 3C shows an example of a frame transmitted from the engine ECU 10. One-byte data includes the engine speed calculated from the detection signal from the engine speed sensor 12 and the water temperature sensor 11. The engine water temperature based on the detection signal is included.

It should be noted that, in addition to those shown in these specific examples, flag data indicating the normal / abnormal of various control data such as detection data calculated based on the various detection signals and calculation data of the control amount are also included. That is, the ECUs 10, 2
0, 30, and 40 represent a part of the control data required for control,
The control data is received from another ECU by data communication using the communication control circuit 70 and the communication line 50, and the control data is received from another ECU.
It is shared with the CU.

Next, the ECUs 10, 20, 30, 4
The processing executed at 0 will be described. As described above, each of the ECUs 10, 20, 30, and 40 is connected to the frame F
The frame F can include the flag data (see FIG. 3) as described above.
FIG. 4 shows a process of writing the flag data.

In the first step S10 of the flag data write processing routine shown in FIG. 4, it is determined whether the flag data to be transmitted is valid or invalid. Note that "the flag data to be transmitted is invalid" means that, for example, the flag data itself has not been determined, or there is an abnormality in a sensor or the like necessary for determining the flag data, and the flag data cannot be determined. For example. For example, the flag data itself is often not determined while the power is supplied and the initialization processing is being performed. When a detection signal from a sensor or a switch is taken in for a predetermined time or more and is determined for the first time, the flag data in the period until the determination is invalidated.

The presence of an abnormality in a sensor or the like can be determined as follows. For example, in the case of the idle switch flag data shown in FIG.
From the correlation between the detection signal from the throttle opening sensor 41 connected to U40 and the detection signal from the idle switch 42, it can be determined whether the idle switch 42 is abnormal. That is, when the idle switch 42 is turned off (not in the idle state) while the throttle opening is 0, it can be determined that the idle switch 42 is abnormal. If abnormal, the flag data of the idle switch is determined to be invalid.

On the other hand, in the case of the neutral switch flag data shown in FIG. 3B, the throttle opening obtained from the vehicle ECU 40 is accelerating, the gradient is constant, and the vehicle speed obtained from the ABS-ECU 20 When the neutral switch 32 is ON even when the neutral switch 32 is on, the neutral switch 32
Is determined to be abnormal. In addition, if the flag data indicates that the ECT shift is being performed, it is determined that the flag data is invalid when an abnormality occurs in the shift actuator 33 and the ECT-ECU 30 cannot perform control. The ECT-ECU 30 monitors the control voltage for the speed change actuator 33. If this voltage is less than a predetermined value, it is assumed that no control signal has been transmitted, and it is determined that control is impossible in that state. I do.

As described above, the first step S11 in FIG.
If the flag data is 0, it is determined whether the flag data is valid or invalid. If the flag data is valid (S110: YES), the flag data is written as it is in S120. The frame F in which the flag data is written in this manner is sent out from the communication control circuit 70 (see FIG. 2) to the communication line 50 at a predetermined transmission timing when other data is similarly written and the transmission is ready. You.

On the other hand, if the flag data is invalid (S110: NO), the flow shifts to S130 to determine whether a specific invalid pattern is being transmitted. And
If the invalid pattern is not being transmitted (S130: NO),
In S140, the first data of the specific invalid pattern is written, and if the specific invalid pattern is being transmitted (S13)
0: YES), write the next data of the specific invalid pattern in S150. In the frame F in which the data of the specific invalid pattern is written in S140 and S140, when the other data is similarly written and the transmission is ready,
The data is transmitted from the communication control circuit 70 to the communication line 50 at a predetermined transmission timing.

Here, the "specific invalid pattern" related to the processing of S130 to S150 will be described in detail.
In general terms, when the flag data to be transmitted is invalid, it is necessary to distinguish it from the case where the flag data is valid by some method. Conventionally, as a technique for making the distinction, for example, a method of securing another flag data area indicating validity or invalidity for each flag data has been considered. However, in this case, two bits are required to exchange 1-bit flag data.
Therefore, in the multiplex communication system 1 of the present embodiment, the corresponding flag data string in a plurality of continuous frames having the same frame ID is changed so as to have a specific invalid pattern. Is not required to be prepared separately from the flag data.

In other words, although the flag data itself is used and no separate data is provided, it is considered that the data is invalid by changing the array to a specific invalid pattern by considering the "flag data string" unit. I was trying to inform them. As will be described later, the receiving side may similarly determine whether or not the corresponding flag data string in a plurality of consecutive frames having the same frame ID is a specific invalid pattern. It is to be noted that the limitation such as “having the same frame ID...” Means that in general frame transmission, a plurality of types of frames are mixed instead of simply transmitting only one type of frame continuously. This is because it is transmitted. That is, since the frame ID is included to distinguish those frames, the same frame ID is used.
, The target flag data is included in the frame.

Various "specific invalid patterns" are conceivable. For example, a pattern in which the state in which the flag data is inverted once each time continues for a predetermined number of times or more can be used. For example, when the ON / OFF of the switch is indicated by the flag data “1” and “0”, the state of the switch is set to “O” at each frame transmission timing.
Inverting in the order of N → OFF → ON → OFF → ON... Cannot occur from the actual control.
When transmitted in a pattern such as "10101", it can be notified that the flag data is invalid. In addition,
As described above, the corresponding flag data string in a plurality of consecutive frames having the same frame ID is a specific invalid pattern "10101", and this is illustrated in FIG. That is, if certain flag data in the first transmission frame F is invalid, 1
The first time is "1", the second time is "0", the third time is "1", the fourth time is "0", and the fifth time is "1".

As described above, in order to write data with a specific invalid pattern, it is determined whether or not an invalid pattern is transmitted in S130 of FIG. 4, and if the invalid pattern is not being transmitted (S130: N
O), the first data “1” of the specific invalid pattern “10101” is written (S140). Then, when the next flag data writing process is executed, an affirmative determination is made in S130, so that “0” which is the next data of the invalid pattern is written in S150. After the process of S150 is repeated and the last data “0” is written,
If a negative determination is made at 110, that is, if it is determined that the flag data is invalid, the invalid pattern "10101" is written again from the beginning.

Incidentally, the "specific invalid pattern" may be set based on rules for transmission and reception among the ECUs 10, 20, 30, and 40, not from the viewpoint of a pattern that cannot occur in control as described above. For example, if the flag data is valid, the same data is transmitted continuously, and the receiving side sets a rule that the received flag data is valid only when the same flag data is received twice consecutively. is there. That is, when the data is continuously received as “11”, the flag data is determined as “1”,
When "00" is continuously received, the flag data is determined as "0". In this way, if the same data is transmitted and received in a state where the same data is not continuous such as "10" or "01", it can be notified that the flag data is invalid.

As described above, when the flag data is valid, the same data is continuously transmitted. On the receiving side, the received flag data is valid only when the same flag data is received twice consecutively. In this embodiment, the transmission period of the flag data, that is, the transmission period of the frame F having the same frame ID is set to the shortest period for changing the content of the flag data (the shortest data change period). ) Or less. If the flag data is, for example, the idle switch 42 (FIG. 1)
) Indicates the ON / OFF state of, for example, 1
If the configuration is such that the state is detected every 0 ms and ON or OFF is updated, then 10 ms is the shortest data change cycle. Therefore, in this case, the transmission period of the flag data, that is, the transmission period of the frame F having the same frame ID is set to 5 (one half of 10 ms).
ms or less. In this way, when the flag data switches from the valid state to the invalid state, the receiving side maintains the previous valid state flag data until it determines that the received flag data is invalid. Can be kept. Therefore, the inconvenience of performing some processing based on invalid flag data can be avoided.

The “invalid pattern that cannot occur in control” and the “invalid pattern set based on the rules for transmission and reception between the ECUs 10, 20, 30, and 40” are not necessarily alternatives. Instead, they may have both of these properties. For example, “10101” as an example of an invalid pattern that cannot occur from the actual control described above indicates that the same data is not continuous such as “10” or “01”.
A case where an invalid pattern is based on an agreement for transmission and reception between 0, 30, and 40 also corresponds to a “specific invalid pattern”.

As described above, when the flag data is invalid, the “invalid pattern that cannot occur in control” and the “E
Next, the flag data is received on the premise that the invalid pattern "10101" having both properties of the "invalid pattern set based on the agreement at the time of transmission and reception between the CUs 10, 20, 30, 40" is transmitted. ECU1
The processing executed by 0, 20, 30, and 40 will be described with reference to FIG.

First, in the first step S210, it is determined whether or not the received flag data is a flag valid pattern. This is, as described above, the ECU 10, 2
According to the rules for sending and receiving between 0, 30, and 40,
If the flag data is valid, the same data is to be transmitted continuously. Therefore, the receiving side determines that the flag is valid when the same flag data is received twice consecutively.

If the flag data is a flag valid pattern (S210: YES), the received flag data is stored in the flag data storage area DA1 in the memory 60a (see FIG. 2).
(See FIG. 6) (S220). Further, "1" indicating "valid" is set in the status flag storage area DA2 (see FIG. 7) in the memory 60a, and the processing routine is terminated.

On the other hand, if the received flag data is not a flag valid pattern (S210: NO), it is determined in S240 whether the received flag data is a flag invalid pattern. Then, the flag data has the flag invalid pattern “10101”.
If (S240: YES), “0” indicating “invalid” is set in the status flag storage area DA2 (see FIG. 7) in the memory 60a, and the processing routine ends. Note that the flag data has the flag invalid pattern “101”.
If it is not "01" (S240: NO), this processing routine is terminated.

If a negative determination is made in S240, it means that neither the flag valid pattern nor the flag invalid pattern is used, for the following reason. That is,
The case where the flag is not the flag valid pattern (S210: NO) is a case where the same data is not received continuously.
Specifically, this is a case where data is received such as "10" or "01". However, since the flag invalid pattern is “10101”, it is not determined that the data is invalid unless data for five times is collected. Looking at two adjacent data while shifting the invalid pattern “10101” determined in S240 one by one, “10” → “01”
→ “10” → “01”. These are all S21
If the determination is negative, the process proceeds to S240.
The object to be judged with 0 is “10” → “101” → “101”
0 "→" 10101 ". Therefore, the affirmative determination is made in S240 for the first time when “10101” is finally reached, and a negative determination is made until then.

The above is a description of the processing related to the exchange of the flag data between the ECUs 10, 20, 30, and 40. Next, the case where the flag data received by the ECUs 10, 20, 30, and 40 is used will be described. The control process will be described with reference to FIG. First, in the first step S310, it is determined whether or not the status flag corresponding to the flag data to be used is valid. The flag data to be used is stored in the memory 6
0a (see FIG. 2) is taken out from the flag data storage area DA1 (see FIG. 7). At this time, the corresponding status flag stored in the status flag storage area DA2 (see FIG. 7) is "valid". It is determined whether it is.

If the status flag is valid (S310: Y
ES), the flag data to be used is taken out from the flag data storage area DA1 (S320), and a predetermined normal process is executed (S330). On the other hand, if the status flag is invalid (S310: NO), a predetermined abnormality process is executed (S340).

In this way, when invalid flag data is received, the normal processing (S330) is executed based on the valid flag data, but the predetermined abnormal processing without using the flag data (S340). To perform
Execution of inappropriate processing can be prevented.

The normal process in S330 is a normal process using flag data, so there is no need to particularly mention it. However, the abnormal process in S340 is a process performed without using flag data. This will be described. For example, when the state flag of the flag data of the idle switch is invalid, as shown in FIG. 3A, the state of the idle switch 42 is determined based on the throttle opening information in the same frame as the flag data of the idle switch. Is estimated. Then, the same process as the normal process in S330 is executed using the estimated state of the idle switch.

When the state flag of the flag data of the neutral switch is invalid, for example, the following two cases can be considered. First, as a first plan, a logic for estimating the state of the neutral switch based on the fluctuation state of the engine speed and the throttle opening information is executed.
Then, using the estimated state of the neutral switch, a process similar to the normal process in S330 is executed.
The second option is that the neutral switch is ON / OFF.
Assuming a control logic that refers to a map corresponding to each case, control is executed with the neutral switch turned on as an abnormal time process in S340. However, in the case where the neutral switch is actually turned off, it is expected that the engine speed will be reduced by performing such control. Therefore, the engine speed is monitored, and if the speed is significantly reduced, the map for the neutral switch OFF is displayed. Reference and control. In this case, a dedicated map may be referred to. If the status flag of the flag data during the ECT shift is invalid, the following abnormal process may be considered. That is, based on the constant at low torque between when the control signal to the shift actuator 33 is switched and during normal operation, an intermediate constant between them is set, and even if the transmission is constantly shifted, a load is applied to the transmission. Control so that the torque is reduced to such an extent that it is not applied. Note that if the torque reduction in this case is greater than the torque reduction during shifting, the shift shock is slightly larger.

In this case, during the processing at the time of abnormality, the fact that the flag data itself during shifting is not received is stored as a diagnosis. This is effective, for example, when a vehicle is diagnosed due to a complaint that no torque is generated by a user of the vehicle. That is,
The absence of torque is due to the execution of the predetermined abnormal-time process, and it is easy to determine that the corresponding ECU 10, 20, 30, 40 itself was operating normally.

As described above, in the case of the multiplex communication system 1 of the present embodiment, the corresponding flag data string in a plurality of consecutive frames having the same frame ID is changed so as to have a specific invalid pattern. The invalidity of the flag data is notified. Therefore, there is no need to prepare data indicating valid / invalid separately from the flag data as in the related art. A plurality of ECUs 10, 20, 30, 4
In a system in which the amount of essential data that needs to be transmitted and received between 0 is large, it is very effective that data is unnecessary separately from the flag data and the amount of data to be transmitted can be reduced. In particular, the multiplex communication system 1 includes an engine ECU 10, an ABS-ECU 20, an ECT-ECU 3
0, and is applied as a control system for a vehicle including a plurality of control devices such as a vehicle ECU 40.
In the case of 10, 20, 30, and 40, real-time processing is often required in addition to simply processing in parallel, due to the characteristics of the control system. Therefore, ECU1
Data transmission / reception between 0, 20, 30, and 40 requires high speed. Therefore, reducing the amount of data to be transmitted / received is very advantageous in terms of improving the speed of data transmission / reception.

In this embodiment, S130 to S in FIG.
The process 150 corresponds to a part of the process of the invalid transmission unit. In other words, the process of changing the corresponding flag data sequence in a plurality of continuous frames into a specific invalid pattern and writing the same in the frame is the process of S130 to S150. It is a process as a means. Further, the processing of S240 in FIG. 6 corresponds to processing as invalidity determination means, and the processing of S240 in FIG.
The processing of 210 corresponds to the processing as validity determining means. Further, the processing of S330 and S340 in FIG. 8 corresponds to the processing as the processing execution means.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of a multiplex communication system according to an embodiment.

FIG. 2 is a view showing each ECU constituting the multiplex communication system of FIG. 1;
FIG. 3 is a block diagram illustrating an internal configuration of the device.

FIG. 3 is an explanatory diagram showing a configuration of a frame transmitted from an ECU.

FIG. 4 is a flowchart showing a flag data writing process executed by each ECU.

FIG. 5 is an explanatory diagram showing five frames in which invalid pattern data is written.

FIG. 6 is a flowchart showing a process executed by each ECU when receiving flag data.

FIG. 7 is an explanatory diagram showing a storage area for flag data received by a flag data reception process and an area for setting a corresponding state flag;

FIG. 8 is a flowchart showing a control process using flag data executed by each ECU.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multiplex communication system 10 ... Engine control device 11 ... Water temperature sensor 12 ... Engine speed sensor 13 ... Injector 14 ... Ignition device 20 ... ABS-ECU 21 ... Wheel speed sensor 22 ... Brake actuator corresponding to each wheel 30 ... ECT- ECU 31 shift lever switch 32 neutral switch 33 speed change actuator 40 vehicle ECU 41 throttle opening sensor 42 idle switch 43 brake switch 44 gradient sensor 45 meter indicator 50 communication line 60 CPU 60a ... Memory 62 ... Input interface 64 ... Output interface 66 ... Bus 70 ... Communication control circuit 70a ... Transmission memory 70b ... Reception memory 72 ... Data transfer line

Claims (5)

[Claims] 1. A frame in which a flag data area including at least one bit data of one bit is set is transmitted and received between a plurality of nodes connected via a communication line via the communication line. In the multiplex communication system, when each of the nodes has invalid flag data to be transmitted, a corresponding flag data sequence in a plurality of consecutive frames having the same frame ID has a specific invalid pattern. Transmission control means for transmitting the frame by changing, and invalidity determining means for determining whether or not a corresponding flag data string in a plurality of frames having the same frame ID among the received frames is the specific invalid pattern. A multiplex communication system, comprising: 2. The multiplex communication system according to claim 1, wherein the flag data string of the specific invalid pattern is set such that a state in which the flag data is inverted every time is continued for a predetermined number of times or more. A multiplex communication system, comprising: 3. The multiplex communication system according to claim 1, wherein an interval at which each of the nodes transmits the frame is set to a half or less of a shortest data change period at each of the nodes. In addition, the transmission control means sets the same flag data continuously when the flag data to be transmitted is valid, and sends one transmission when the flag data to be transmitted is invalid. Each node is configured to invert flag data every time, and each of the nodes is provided with validity determining means for determining that the flag data is valid when the received flag data is the same twice in succession. Characteristic multiplex communication system. 4. The multiplex communication system according to any one of claims 1 to 3, wherein each of said nodes further comprises: A predetermined normal process based on the received valid flag data is performed. On the other hand, if the flag data sequence is determined to be an invalid pattern, a predetermined abnormal process not using the received invalid flag data is performed. The multiplex communication system according to any one of claims 1 to 3, further comprising a processing execution unit that executes the processing. 5. The multiplex communication system according to claim 1, wherein each node is configured as a control device for controlling each part of a vehicle. 5. The multiplex communication system according to any one of 4.