JPH06290160A - Data communication method between microcomputers and multi-microcomputer system - Google Patents

Abstract

PURPOSE:To improve the reliability of data communication by executing processing related to transmitted data in the case that returned data and the transmitted data coincide with each other. CONSTITUTION:A transmitting side 1 is provided with a transmitted data storage means 12 to store the transmitted data, a coincidence detecting means 13 to judge whether the transmitted data stored in the transmitted data storage means 12 and the returned data returned from a receiving side 2 coincide with each other or not by comparing them with each other, and an acknowledge signal transmitting means 14 to transmit an acknowledge signal to the receiving side 2 when the transmitted data and the returned data coincide with each other. Besides, the receiving side 2 is provided with a received data storage means 22 to store the transmitted data sent from the transmitting side after receiving it, and an acknowledge signal receiving means 23 to execute the processing of this transmitted data after receiving the acknowledge signal sent from the transmitting side. Then, the transmitted data is returned immediately to the transmitting side, and whether the returned transmitted data and the transmitted data coincide with each other or not is confirmed, and only when coincidence is confirmed, the processing related to the transmitted data is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication method in a multi-microcomputer system including a plurality of microcomputers (hereinafter abbreviated as "microcomputers") connected by bidirectional communication paths, and a structure therefor. And a multi-microcomputer system suitable for controlling an engine of an automobile.

[0002]

2. Description of the Related Art When configuring a control system using a microcomputer, one microcomputer does not perform all the control, but the control process is divided into a plurality of parts, and a separate microcomputer is assigned to each process. In some cases, the data of another microcomputer required in (1) may be configured in a form called a multi-microcomputer system so that it can be obtained through a bidirectional communication path connecting between the respective microcomputers. FIG. 10 is a diagram showing a configuration example of a multi-microcomputer system. Here, although it is composed of two microcomputers of a first microcomputer 1 and a second microcomputer 2 connected by a communication path 3, It may be configured. In that case, the communication path may be connected to a common path or may be provided between the respective microcomputers. By using such a configuration, the use of low-performance microcomputers and the reduction of wire harness by properly arranging each microcomputer reduce overall cost, and the reliability of mutual monitoring by each microcomputer is improved. The effect is obtained.

A multi-microcomputer system is also used in an automobile control system by taking advantage of the above characteristics. For example, different microcomputers are used for engine control and for traction control that secures vehicle stability while controlling the output of the engine at the time of starting and accelerating on slippery roads to obtain effective driving force. Is provided
A multi-microcomputer system is used which enables bidirectional connection between them to exchange data. There is also an example in which the engine control unit (ECU) is composed of two microcomputers.

[0004]

In a multi-microcomputer system, it is necessary that data communication be accurately performed between the respective microcomputers. If data communication is not performed correctly, control will be performed based on incorrect data, and the reliability of control will be impaired. Therefore, in the multi-microcomputer system,
High reliability of data communication is required, and various measures are taken for that purpose, but further improvement is required.

The present invention is intended to meet this demand, and it is an object of the present invention to further improve the reliability of data communication in a multi-microcomputer system.

[0006]

In order to achieve the above object, in the method of data communication between a plurality of microcomputers connected by a communication path of the present invention, the step of sending back the sending data to the sending side by the receiving side and the transmitting step The side compares the returned reply data with the send data to confirm that they are the same, the step of sending a confirmation signal from the sender when the reply data and the send data match, and the receiver to confirm this Is performed, and the receiving side performs processing relating to transmission data after receiving the confirmation signal.

FIG. 1 is a diagram showing the basic configuration of the multi-microcomputer system of the present invention. As shown in FIG. 1, the multi-microcomputer system of the present invention includes a plurality of microcomputers 1, which are connected by a bidirectional communication path 3 and include communication means 11 and 21 for transmitting and receiving data via the communication path 3. In the multi-microcomputer system composed of 2, the receiving side 1 is
Transmission data storage means 12 for storing transmission data, transmission data stored in the transmission data storage means 12, and receiving side 2
Matching detection means 13 for comparing the reply data sent back from the sender to determine if they match, and confirmation signal sending means 14 for sending a confirmation signal to the receiving side 2 when the send data and the reply data match. The receiving side 2 includes received data storage means 22 for storing after receiving the transmission data sent from the transmitting side, and confirmation signal receiving means 23 for processing the transmission data after receiving the confirmation signal sent from the transmitting side. The communication means 21 on the reception side stores the transmission data in the reception data storage means 22, and then immediately returns the data to the transmission side 1. Although reference numeral 30 indicates a dedicated signal line for confirmation signal, it may not be necessary in some cases.

[0008]

According to the data communication method in the multi-microcomputer system of the present invention, the transmission data is immediately sent back to the transmission side, and it is confirmed that the returned reply data and the transmission data match, and it is confirmed that they match. Since the processing relating to the transmission data is performed only when the transmission data is processed, the transmission data to be processed is only the correctly transmitted data. Therefore, processing is not performed based on erroneous data, and the reliability of the system is improved.

[0009]

FIG. 2 is a diagram showing the configuration of a first embodiment in which the present invention is applied to a multi-microcomputer system constituting an engine control unit (ECU) of an automobile. In FIG. 2, reference numeral 10 is an engine control unit, 1 is a first microcomputer, 2 is a second microcomputer, 6 is a battery, and 7 is a battery.
Is an ignition switch, 8 is a main relay, 9
Indicates a power supply circuit. First microcomputer 1 and second microcomputer 2
Are central processing units (CPU) 41, 51 and R, respectively.
AM 42, 52, DMA controller 43, 53,
Serial communication ports (SCI) 44, 54 and SCI4
Clock generator 4 for supplying clock signals to 4 and 54
5 and 55 are provided. The RAMs 42 and 52 are provided with standby RAMs 421 and 521 that always hold the stored data regardless of the state of the ignition switch 7. The SCIs 44 and 54 are circuits for converting 8-bit data into serial data and transmitting the data one bit at a time. The transmission of data from the SCI44 of the first microcomputer 1 to the SCI54 of the second microcomputer 2 is performed via the communication line 31. Data transmission from the SCI 54 of the second microcomputer 2 to the SCI 44 of the first microcomputer 1 is performed via the communication line 32. Reference numeral 33 is a communication line for clock signals. Reference number 3
Reference numerals 4 and 35 are communication paths for confirmation signals, which will be described later, and 3
Reference numeral 4 is for a confirmation signal from the first microcomputer 1 to the second microcomputer 2, and 35 is for a confirmation signal from the second microcomputer 2 to the first microcomputer 1. In the drawings, corresponding functional parts are designated by the same reference numerals.

The engine control unit 10 is controlled by the ignition switch 7 so as to be in an operating state (on state). Even if the ignition switch 7 is in an off state, the data necessary for the next operation is stored. It enters the standby state in which it performs the minimum required operations such as holding. The amount of power consumption in the standby state is small, and the battery 6 is not consumed in the standby state. Therefore, the power lines from the battery 6 to the power circuit 9 are two systems, a standby system directly connected and a main system via the main relay 8, and are supplied from the standby even if the ignition switch 7 is turned off. The engine control unit 10 is configured to enter a standby state by electricity. During standby, the CPUs 41 and 51 and the standby RAM 421,
Electricity is supplied to 521. Standby RAM 421, 5
21 stores data required for the next operation.

When the operation is started, the ignition switch 7 is turned on. In response to this, the main relay 8 is connected, and electricity is supplied to the power supply circuit 9 via the main system. At the start of operation, initialization is performed to set each part of the control unit to a predetermined state and inspect the state of each part. At this time, the data stored in the standby RAMs 421 and 521 are read out, each part is set according to the data, and part of the data is transmitted to the other microcomputer via the communication lines 31 and 32. It During normal operation, depending on the needs of the control process,
Data communication is performed between the two microcomputers. Further, even when the ignition switch 7 is turned off to stop the operation, a part of the data necessary for starting the next operation is transmitted to another microcomputer and then the standby RAMs 421 and 521 are provided.
The operation of storing is performed.

In the data communication, the DMA controller 43 or 53 is instructed of the position in the RAM 42, 52 of the data to be transmitted by the CPU 41 or 42 and the number of bytes.
In response to this, the DMA controllers 43 and 53 are the CPU 4
1, 42 are separated from the internal bus, and the data stored in the designated positions in the RAMs 42, 52 are stored in the SCIs 44, 5
4, and the SCIs 44 and 54 convert the data into serial data and transmit the serial data. It is also possible to perform data transfer to SCI by the CPU without using the DMA controller.

Next, the data communication processing in this embodiment will be described with reference to the flowchart of FIG. In data communication in a conventional multi-microcomputer system, it was not confirmed whether the received data was normally sent by simply transmitting the data from the transmitting side and receiving the data at the receiving side. On the other hand, in this embodiment, the data received by the receiving side is sent back once, and the sent back data is compared with the original data sent to confirm that they match. In this embodiment, any of the microcomputers can be the transmitting side, but here, it is assumed that the first microcomputer 1 is the transmitting side and the second microcomputer 2 is the receiving side, and the data to be transmitted is 1 byte.

On the transmitting side, in step 301, the CPU 41
Store the transmission data to be transmitted by the RAM in another position in the RAM 42. This process is not necessary if the transmitted data is not rewritten during communication. Step 30
2, the DMA controller 43 is the same as the conventional transmission.
Transfers the transmission data to the SCI 44, and the SCI 44 converts the serial data into the serial data for transmission. In response to this, in the second microcomputer 2 on the receiving side, in steps 321 and 322, S
After converting the serial data received by the CI 54 into 8-bit parallel data, the DMA controller 53
Store in M52.

In step 323, the CPU 51 instructs the DMA controller 53 at the position where the received data is stored and sends the received data back. In response to this, in the same way as the above-mentioned operation, on the transmitting side, the reply data is stored in a predetermined position of the RAM 42 in step 303. In step 304, the CPU 41 compares the transmission data in the RAM 42 with the reply data, and it is determined in step 305 whether they match. If they match, then it is normal, so in step 306 a confirmation signal is transmitted via the signal line 34. The CPU 51 on the receiving side determines in step 324 whether or not the confirmation signal has been received within a predetermined time,
If the confirmation signal is received, the returned data is normal. Therefore, the received data stored in step 325 is stored at the position where the data should be stored, and the data up to that point is rewritten for normal operation. I do.

If the transmission data and the reply data do not match, various countermeasures can be considered. Here, the same data is transmitted again, the transmitting side waits for a predetermined time in step 307, and then returns to step 301. The above process is repeated. The receiving side waits when the confirmation signal cannot be received within a predetermined time, and waits for a request for data transmission from the transmitting side again. The microcomputers 1 and 2 actually perform many other processes in parallel by the multitasking method, and are not merely waiting. Therefore, in some cases, it may be necessary to perform processing based on the transmitted data while the receiving side cannot receive the confirmation signal. In such a case, the data obtained in the previous communication is used as it is for processing. Using the previous data is less harmful than using the wrong data, because the data does not change very quickly in a short time.

Further, when the transmission data and the reply data do not match, it is also an effective method to initialize the data so as to be in a predetermined state. As described above, the present embodiment applies the present invention to a multi-microcomputer system of an automobile engine control unit. In such a multi-microcomputer system, when the ignition switch 7 is turned on and the system is activated. Also, when the ignition switch 7 is turned off and the system is terminated, data is transmitted between the microcomputers and necessary processing is performed. At startup, the data stored in the standby RAM is transmitted, and the transmitted data is stored and used for subsequent processing. This data is transmitted as needed, and the data up to that point is rewritten with new data, but there is no data up to that point at startup, and if an error occurs in the transmitted data, the data up to that point will be used. Data transmission at start-up is especially important because it is not possible. Data transmission at the end is also important because the next process is started based on the transmitted data. 4 and 5 are timing charts showing the data transmission process at the time of startup and at the time of termination in this embodiment. FIG. 4 is a timing chart at the time of startup, and FIG. 5 is a timing chart at the time of termination.

As shown in FIG. 4, when the ignition switch (IGSW) 7 is turned on at the time of starting, the main relay 8 is connected and the engine control unit 10 is started. According to this, CPU of each microcomputer
Performs initialization operation, and one of the operations is standby RA
The data stored in M is read out, the setting according to the data is performed in the microcomputer, and the data is transmitted to another microcomputer. S1 indicates a transmitting operation of the first microcomputer 1, J1 indicates a receiving operation of the second microcomputer 2, H1 indicates a transmitting operation for reply data of the second microcomputer 2, and JH1 indicates a receiving operation for reply data. When the reply data is received, the data is confirmed. If they match, the confirmation signal K1 is sent from the first microcomputer 1 to the second microcomputer 2. When the second microcomputer 2 detects this confirmation signal K1,
The confirmation signal K1 is returned to the original "H" level. The second microcomputer 2 performs a predetermined operation W1 such as writing data according to the confirmation signal K1.

The same operation is performed for the next data, but it is assumed that the reply data and the transmission data do not match. In that case, the confirmation signal is not transmitted, and the confirmation signal is not received within the predetermined time on the receiving side, so that the receiver is in a standby state. In this state, a request for data transmission is issued again, so that it is recognized that the previous data was retransmitted, the same operation is repeated, and data is transmitted. If abnormalities occur in the transmission many times, it means that there is a failure, so each microcomputer is initialized to notify the occurrence of the failure.

As shown in FIG. 5, even if the ignition switch (IGSW) 7 is turned off at the end, the main relay 8 is still connected and the engine control unit 10 is also kept on. Then, after the communication of the necessary data is completed, the signal from the first microcomputer 1
The main relay 8 is turned off and the engine control unit 10 is also turned off. Data transmission is performed in the same manner as the timing chart of FIG.

As described above, data transmission at the time of startup and at the time of termination is particularly important, and the data confirmation processing for sending back and confirming the transmission data is performed only for the data transmission at the time of activation and at the time of termination. Regarding data transmission, a transmission method may be used in which the same data confirmation processing as in the past is not performed, or the data confirmation processing may be performed for all transmission data.

In the multi-microcomputer system of the engine control unit of the automobile, the transmission speed is changed according to the type of data to be transmitted. For example, it is divided into two types of transmission speeds, a high speed system and a low speed system.
32 ms, 64 ms and 128 ms for 3 steps, low speed system
Each stage can be selected, and the transmission rate can be set according to the type of data. When the above data confirmation processing is performed, the transmission speed will be slower than the conventional transmission due to the confirmation processing, but the high-speed system is used for data that needs to be transmitted at high speed. It is not preferable to perform the data confirmation processing of the present invention by the above data transmission. Therefore, it is advisable to adopt a transmission method that does not perform the data confirmation processing similar to the conventional method for data transmission in the high speed system, and apply the transmission method that performs the data confirmation processing of the present invention only in the low speed system.

Further, the transmitted data includes data related to highly urgent control such as fuel system and ignition system, and data related to relatively less urgent control such as display to the driver. is there. Since the data related to the control with high urgency needs to be processed as quickly as possible, the data confirmation processing of the present invention is performed only for the transmission of the data related to the control with relatively low urgency for the same reason as above. You may do it. In addition, data related to control with a high degree of urgency is processed promptly, but after the data confirmation processing after processing is performed and it is stored after confirming that data transmission was performed normally, it is stored in subsequent processing. It may be used as it is.

Furthermore, the transmitted data is data that is updated on the receiving side by replacing the existing data with the newly transmitted data, but the update period differs depending on the type of data. That is, the data transmission cycle is different. Since data with a long cycle is used for a long time after being transmitted once, if there is an abnormality during transmission, its effect is great. Therefore, the data confirmation processing of the present invention may be performed only on data having a long update cycle.
For the same reason, data that is processed only once after being transmitted but not stored is less affected than data that is stored and used many times. Therefore, the data confirmation processing of the present invention is applied only to stored data. It may be performed.

Various examples of performing the data confirmation processing on only a part of the data have been described above. However, when an abnormality occurs in the data transmission due to disturbance or the like, the normal transmission state does not change frequently. If it is confirmed that normal transmission can be performed, normal transmission can be normally performed for a certain period of time. Therefore, it is possible to confirm the reliability of data transmission without performing data confirmation processing for all data as described above, and if there is an abnormality when performing data confirmation processing, take measures against it. You can also do it. Therefore, the data confirmation processing may be periodically performed on the data to be transmitted.

Further, in addition to the normal data transmission, special data transmission may be performed in order to confirm the transmission status by performing a data confirmation process. In this case,
Since it is only necessary to confirm the transmission status with the central microcomputer (master microcomputer), it is not absolutely necessary to send a confirmation signal. The transmission data in the case of performing such special data transmission for confirming the transmission status is preferably data in which an abnormality is easily found, for example, data in which 1 and 0 such as hexadecimal A5 and 5A are alternately arranged. .

The first embodiment and its modification have been described above. In the first embodiment, the CP is used for transmitting the confirmation signal.
It was performed via a dedicated signal line provided between U. But,
Providing a dedicated signal line separately has a problem that the number of wiring lines increases. Therefore, in the second embodiment, the confirmation signal is transmitted via the data communication path. The multi-microcomputer system of the second embodiment has substantially the same configuration as that of FIG. 2, but the signal lines 34 and 35 for confirmation signals are used.
The point that is excluded is different.

FIG. 6 is a diagram showing a bit configuration of data transmitted and received in the second embodiment. (1) is data first transmitted from the transmission side to the reception side, and (2) is the reception side. Is the data sent back from the sending side to the sending side, and (3) is the data sent from the sending side to the receiving side as a confirmation signal. The data of the confirmation signal is a logical value of an appropriate bit, for example, the least significant bit (LSB) or the most significant bit (MSB), and indicates whether the transmission is normal or abnormal. If the confirmation signal is transmitted in such a format, it is not necessary to indicate that there is an abnormality by the absence of the signal. As described above, in the second embodiment, it is not necessary to provide a dedicated confirmation signal line, but it is necessary to perform data transmission three times for one data transmission.

In the bit configuration of the confirmation signal of the second embodiment shown in FIG. 6, 8-bit data was used as the confirmation signal, but only 1 bit is actually used, that is, 8-bit data. No need. Therefore, as the confirmation signal, only 1 bit may be transmitted. However,
In the configuration shown in FIG. 2, D is used to transfer data from the RAM.
It uses the MA controller and cannot transfer only 1 bit. Therefore, in this case, the CPU transfers to the SCI.

In the first and second embodiments, the confirmation signal indicating that the data transmission is normal is sent when all the 8-bit transmission data match, but in the confirmation signal data bit configuration of FIG. 1 is used as a signal
Only bits, other bits are redundant. Therefore,
FIG. 7A shows the bit configuration in the modified example of the second embodiment in which the confirmation signal for each bit of the transmission data is sent using the remaining bits.

Further, instead of sending a 1-bit confirmation signal every time 8-bit data is transmitted as in the second embodiment, 8-bit data is continuously transmitted an appropriate number of times of 8 times or less,
FIG. 7 (2) shows the bit configuration of the confirmation signal in the modified example in which the confirmation signals are collectively transmitted in one transmission. In this example, 8-bit data is
The figure shows the case of continuous transmission. In this example, the transmission of the confirmation signal is reduced to 1/8. However, it cannot be applied to highly urgent data because the process of using the data cannot be started until the transmission of a total of 8 bytes of data is completed.

Further, when the CPU, not the DMA controller, performs the transfer to the SCI, the number of transmission bits can be set relatively freely. Therefore, FIG. 8 shows a modified example of the data bit structure in which one transmission data is 9 bits and 1 bit thereof is assigned to the confirmation signal. As shown in the figure, the data to be transmitted is 8 bits, and the remaining 1 bit is assigned to the confirmation signal. The transmission data may be the previous transmission data corresponding to this confirmation signal, or may be the confirmation signal of the next transmission data and the previous transmission data. In that case, the confirmation signal should be on the stop bit side.

In the microcomputer system, when the power is turned on and the system is started up, it is inspected whether or not each unit constituting the system such as RAM normally operates, and then the normal operation is started. Such a function is called a self-diagnosis function (diagnosis function). Such self-diagnosis operation is also performed in the engine control unit, but it is quite necessary for RAM inspection (for example, whether the value exceeds the control value guard or whether the data structure is not corrupted). Since it takes time, the setting of each unit and data communication may be performed first. If the RAM is found to be abnormal, the transmitted data may also be abnormal. The third embodiment takes measures against such a case, and its processing is shown in FIG.

On the transmitting side, data is transmitted in step 901, and the RAM is inspected in step 902 until the transmitted data is returned. Then, in step 903, the reply data is received, and in step 90
At 4, it is determined whether the data matches the transmission data. If it is confirmed in step 905 that the transmitted data and the reply data match and there is no abnormality in the RAM, a confirmation signal is transmitted in step 907. If there is an abnormality in the RAM, there is a possibility that the transmitted data itself has a problem, so an initialization signal is immediately sent to the receiving side in step 908, and a recovery process including initialization is started in step 909. . On the receiving side, the initialization is performed immediately in response to the initialization signal so that no problem occurs. If the transmission data and the reply data do not match in step 904, further step 906
Check if there is any abnormality in RAM. If there is no abnormality in the RAM, it is an abnormality due to transmission, so step 91
After the standby operation of 0, the same data is transmitted again. If the RAM is also abnormal, the process proceeds to step 908 and the same operation as above is performed. Although this processing is performed after the transmission, the RAM inspection may be performed before the data transmission and the initialization signal may be transmitted. As the initialization signal, the confirmation signal transmission method of the above-described embodiment can be used.

The embodiment of the present invention has been described above.
In the above embodiment, the data transmission is performed by serial communication of 1 bit at a time, but it is also possible to perform parallel communication by transmitting a plurality of bits such as 8 bits in parallel except for a part. .

[0036]

As described above, according to the present invention,
Since the reliability of the data communication between the microcomputers in the multi-microcomputer system is improved, it is possible to improve the reliability of the multi-microcomputer system, and especially when applied to the multi-microcomputer system mounted on an automobile,
Safety is further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a multi-microcomputer system of the present invention.

FIG. 2 is a diagram showing a configuration of a first embodiment in which the present invention is applied to a multi-microcomputer system of an automobile engine control unit.

FIG. 3 is a flowchart showing a process in the first embodiment.

FIG. 4 is a time chart showing a timing at which data confirmation processing is performed in the first embodiment.

FIG. 5 is a time chart showing another timing at which the data confirmation process is performed in the first embodiment.

FIG. 6 is a diagram showing a data bit structure in a second embodiment.

FIG. 7 is a diagram showing another example of a data bit structure in the second embodiment.

FIG. 8 is a diagram showing still another example of the data bit structure in the second embodiment.

FIG. 9 is a flowchart showing a process in the third embodiment.

FIG. 10 is a diagram showing a basic configuration of a multi-microcomputer system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st microcomputer (transmission side) 2 ... 2nd microcomputer (reception side) 3 ... Communication path 11 ... Transmission side communication means 12 ... Transmission data storage means 13 ... Match detection means 14 ... Confirmation signal transmission means 21 ... Reception Side communication means 22 ... Received data storage means 23 ... Confirmation signal receiving means 30 ... Confirmation signal transmission path

Claims (19)

[Claims] 1. A data communication method between a plurality of microcomputers connected by a communication path, wherein a receiving side sends back transmission data to a sending side, and reply data sent back from the sending side is compared with the sending data. Confirming that they are the same, a data confirmation process including a step of transmitting a confirmation signal by the transmitting side when the reply data and the transmission data match, and a step of receiving the confirmation signal by the receiving side. And a receiving side performs processing relating to the transmission data after receiving the confirmation signal. 2. The microcomputer according to claim 1, wherein the transmission of the data is performed at a plurality of communication speeds according to the data, and the data confirmation processing is performed only on the transmission data having a low communication speed. Data communication method between. 3. The micro according to claim 1, wherein the data to be transmitted is divided into stages according to the degree of urgency of the data, and the data confirmation processing is performed only on data having a low degree of urgency. Data communication method between computers. 4. The data to be transmitted is data that is updated on the receiving side by replacing the existing data with newly transmitted data, and is divided into a plurality of update cycles according to the data. 2. The data communication method between microcomputers according to claim 1, wherein the data confirmation process is performed only on data having a long update period. 5. The data communication method between microcomputers according to claim 1, wherein the data confirmation processing is performed periodically. 6. The data communication method between microcomputers according to claim 1, wherein the data confirmation processing is performed only on data stored on the receiving side. 7. The confirmation signal is a dedicated signal path (3
0) The method of data communication between microcomputers according to claim 1, characterized in that communication is performed via 0). 8. The method of data communication between microcomputers according to claim 1, wherein the confirmation signal is assigned to a part of data bits of the transmission data for communication. 9. The transmission of the data is performed in 8-bit units, and data of 8 bytes is collectively and continuously transmitted, and then the confirmation signals of 8 times are collectively transmitted in 1 byte. 9. A data communication method between microcomputers according to claim 8. 10. The micro according to claim 1, wherein the receiving side performs processing by using the data up to that time when the confirmation signal cannot be received within a predetermined period. Data communication method between computers. 11. The data communication method between microcomputers according to claim 1, wherein the receiving side performs an initialization operation when the confirmation signal cannot be received within a predetermined period. . 12. The transmission side transmits a signal indicating a mismatch when the reply data and the transmission data do not match, and when the receiving side receives the signal indicating a mismatch, the data up to that point is used. Claims 1 to 9
5. A data communication method between microcomputers according to any one of 1. 13. The transmission side transmits a signal indicating a mismatch when the reply data and the transmission data do not match, and the receiving side performs an initialization operation when the signal indicating a mismatch is received. A data communication method between the microcomputers according to any one of claims 1 to 9. 14. The transmitting side tests the RAM of the microcomputer after transmitting the data, and when the result of the RAM test is defective, outputs a signal for stopping the storage of the transmitting data on the receiving side. The data communication method between microcomputers according to claim 1, characterized in that. 15. The transmitting side tests the RAM of the microcomputer before or after transmitting the data, and when the result of the RAM test is defective, outputs a signal for causing the receiving side to perform an initialization operation. The data communication method between the microcomputers according to claim 1, wherein 16. The plurality of microcomputers are
A multi-microcomputer system for controlling an engine, wherein the data confirmation processing is performed after the ignition switch is turned off and before the main relay switch is turned off. Data communication method. 17. The plurality of microcomputers are
A multi-microcomputer system for controlling an engine, wherein the data confirmation process is performed immediately after an ignition switch is turned on. 18. A data communication method between a plurality of microcomputers connected by a communication path, wherein a receiving side sends back transmission data to a transmitting side, and the transmitting side compares reply data sent back with the transmitting data. A data communication method between microcomputers, which comprises periodically performing a data confirmation process including a step of confirming that they are the same. 19. A bidirectional communication path (3) for connection,
A multi-mycol computer system comprising a plurality of microcomputers (1, 2) having communication means (11, 21) for transmitting and receiving data via the communication path (3), wherein the receiving side (1) is , Comparing the transmission data stored in the transmission data storage means (12) with the transmission data stored in the transmission data storage means (12) and the reply data returned from the receiving side to determine whether they match. A match detection means (13) and a confirmation signal transmission means (14) for transmitting a confirmation signal to the reception side (2) when the transmission data and the reply data match, the reception side (2) is provided from the transmission side. Received data storage means (22) for storing the transmitted data to be sent and storing the received data, and confirmation signal receiving means (22) for processing the transmitted data after receiving the confirmation signal sent from the transmitting side ( 3) and with a,
The multi-microcomputer system, wherein the communication means (21) on the receiving side stores the transmission data in the reception data storage means (22) and then immediately sends it back to the transmitting side (1).