JP3089905B2 - Communication system for vehicle diagnosis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device mounted on a vehicle, such as an electronic control device for an engine or an electronic control device for a transmission, and a diagnostic tool (diagnostic device) externally connected to the electronic control device. The present invention relates to a vehicle diagnostic communication system that performs data communication for diagnosis.

[0002]

2. Description of the Related Art In recent years, the electronics of vehicles have been remarkable, and on-vehicle devices such as engines and transmissions of various parts of the vehicle have been highly electronically controlled by microcomputers. For this reason, the controllability of these in-vehicle devices has been dramatically improved, but on the other hand, the failure diagnosis of these in-vehicle devices has become increasingly complicated.

For this reason, many on-vehicle electronic control units have been added with a self-diagnosis function, and have been improved so as to perform fault diagnosis of the on-vehicle devices and the control unit itself in addition to controlling the on-vehicle devices to be controlled. Alternatively, the system is connected to an external diagnostic device called a diagnostic tool, and is improved as a system capable of performing more advanced failure diagnosis and analysis of diagnostic data with the support of the diagnostic tool. Various approaches have been devised to address the diagnosis of increasingly complex vehicle systems. In particular, a method of diagnosing a vehicle system via various on-vehicle electronic control devices under the support of the external diagnostic tool can flexibly specify any desired diagnostic data from outside, Moreover, in recent years, it has attracted attention as a method capable of performing highly reliable analysis based on the captured diagnostic data.

[0004] When a vehicle system is diagnosed using an external diagnostic tool in this way, usually, the electronic control unit and the mutual communication means provided in the external diagnostic tool are connected by an appropriate connector such as a diagnostic connector. A control command is transmitted from the diagnostic tool to any electronic control device via the formed communication channel.The electronic control device that has received the control command generates a communication path based on the control command. Start the diagnosis of the target vehicle system. ・ At the end of the diagnosis, send the stop command from the diagnostic tool to the electronic control unit again. Steps such as terminating the running diagnosis are taken. As described above, the diagnosis operation of each electronic control device is controlled based on a command sent from the diagnosis tool. Therefore, in such a communication system, if a connector for electrically connecting the diagnostic tool and the electronic control unit is disconnected during the diagnosis, the electronic control unit itself may not be connected to the connector. Since it cannot be detected that the connector has been disconnected, the diagnosis processing based on the control command immediately before the disconnection of the connector is performed continuously and continuously in these electronic control devices.

Therefore, conventionally, in order to solve such inconvenience in the communication system, for example, Japanese Patent Laid-Open Publication No.
A method as disclosed in Japanese Patent Publication No. 41 is also proposed. That is, in this method, when the diagnosis operation by the various electronic control devices is continued, a preset time, for example, 1 second
c, a continuation command for instructing the continuation of the diagnostic operation is separately transmitted from the diagnostic tool to the electronic control devices. Based on the transmission of the continuation command, the diagnostic operation by the electronic control device is continued. To do. Appropriate time limit means is provided in each of these electronic control units, and after receiving the above-mentioned control command or continuation command, even if a predetermined time specified by the time limit means has passed, any next command is received. If not, the diagnostic operation being executed in the electronic control units is automatically terminated.

[0006]

According to the above-mentioned conventional method, even if the connector for connecting the diagnostic tool and the electronic control unit is disconnected during the diagnosis, the connector is disconnected. The inconvenience that the diagnosis processing based on the immediately preceding control command is continuously executed in the electronic control unit indefinitely is avoided.

However, in the case where it is desired to execute the diagnosis of the vehicle system continuously and at a high speed for a relatively long time, for example, during one trip of the vehicle, such a conventional method still has a problem. For example, a signal detected by a sensor provided in each part of the vehicle is usually written into a built-in RAM through an electronic control unit, and the written RAM value (diagnosis data) is transmitted to a diagnostic tool connected to the above. In order to read out and diagnose the instantaneous abnormality of the detection signal by these sensors through the diagnostic tool, and to accurately trace the transition of the detection signal by the sensor, it is necessary to execute the RAM at high speed and at a constant period. Continuous reading of values must be performed. However, when the processing by the electronic control devices is continued by periodically transmitting the continuation command from the diagnostic tool as in the above-described conventional method, the continuation commands are also received on the electronic control device side. Each time, various processes based on the command must be executed, and such a high-speed and continuous reading of the RAM value at a constant cycle cannot be realized at all.

The present invention has been made in view of such circumstances, and even in the case where the diagnosis of the vehicle system is executed continuously and at a high speed for a relatively long time as described above, such electronic control is performed. It is an object of the present invention to provide a vehicle diagnostic communication system that can guarantee the execution of highly reliable diagnostic processing by a device.

[0009]

In order to achieve the object, according to the present invention, various electronic control units mounted on a vehicle and an external diagnostic device are connected via communication means, and the diagnostic device is selected. A vehicle diagnostic communication system that transmits a request message requesting execution of a diagnostic process to an electronic control device, and the selected electronic control device executes a specified diagnostic process according to the received request message. In the diagnostic device, in the request message,
Incorporating diagnosis duration information specifying the duration of the diagnosis processing, the selected electronic control unit, after receiving the request message, performs the diagnosis processing until the time specified by the diagnosis duration information is reached. The diagnostic processing is executed, and when the time specified by the diagnostic continuation time information is reached, the diagnostic processing being executed is terminated.

[0010]

The diagnosis duration information included in the request message is information for designating the duration of the diagnosis processing corresponding to the contents of the diagnosis processing contained in the message. As long as the contents of the processing do not change, the information is transmitted to the selected electronic control device only once in accordance with the contents of the diagnosis. The selected electronic control device also knows in advance the contents of the diagnostic processing to be executed and the duration thereof based on the reception of the request message.

For this reason, even if the above-mentioned continuation command or the like is not used, the diagnosis processing through the desired electronic control device is continued for an arbitrary time designated by the diagnosis device. In other words, since the continuation command is not required, the electronic control unit can concentrate on the requested diagnostic processing, and the reliability of the continued diagnostic processing result naturally increases. Also, of course, even if the connector connecting the external diagnostic device and the electronic control device is disconnected during the diagnosis,
As a result, the diagnosis processing by the electronic control unit is not performed continuously and endlessly.

In particular, the diagnostic processing required by the diagnostic device for the selected electronic control device is a process of reading out control data held by the electronic control device, and the selected electronic control device is also read out. After the request message is received, the read control data is repeatedly returned to the diagnostic apparatus while incorporating the read control data into the response message until the time specified by the diagnostic duration information is reached, If it is assumed that the reply of the response message is completed when the time specified by the information is reached, the above-mentioned selected electronic control device also performs the above-described RAM value continuous reading processing at a high speed and a constant cycle. Can be realized with high reliability.

[0013]

FIG. 1 shows an embodiment of a communication system for vehicle diagnosis according to the present invention. In the system of this embodiment, a plurality of electronic control units including, for example, an engine control unit 1 and a transmission control unit 2 are connected via a communication line 3 as on-vehicle electronic control units. , A diagnostic tool 5 as an external diagnostic device is connected via a communication line 3 and a diagnostic connector 4. The connected external diagnostic tool 5 and the on-vehicle electronic control device, for example, the engine control device 1
A multiplex communication system called CSMA / CD is used as a communication system between the transmission control device 2 and the transmission control device 2, and a communication protocol for the multiplex communication conforms to the J1850 standard of the American Society of Automotive Engineers (SAE). A protocol shall be used. less than,
The details of each of these elements will be described.

Here, as an example of the on-vehicle electronic control device, its configuration and functions will be described focusing on the engine control device 1. As shown in FIG. 1, the engine control device 1 includes a CPU 11, a ROM 12, a RAM 13, an input circuit 14, an output circuit 15, an A / D conversion (ADC) circuit 16, a communication circuit 17, and the like. I have.

Here, the communication circuit 17 converts the J1850 signal format of the diagnostic request message sent from the diagnostic tool 5, that is, the bit format, into an NRZ (non-return zero) format which can be read by the CPU 11, This is a circuit having a function of inversely converting a response message output from the NRZ system into a J1850 bit format. Note that these bit format conversion functions require too much computational load to be realized by software, and therefore are usually realized by hardware through the communication circuit 17.

An input circuit 14 constituting the engine control device 1 receives a sensor signal mainly composed of a pulse signal output from a sensor such as a crank angle sensor 21 or a vehicle speed sensor 22 for detecting an engine speed. And AD
The conversion circuit 16 receives a sensor signal composed of a digital signal output from a sensor provided in each part of the vehicle, such as a throttle sensor 23, an air flow meter 24, a water temperature sensor 25, and an O2 sensor 26. Each of these sensor signals is converted into a physical quantity corresponding to the detected value by sensor data corresponding to the detected value (to be more precise, by a calculation process by the CPU 11).
It is stored in the data area of the AM 13 and is used as a calculation value for the fuel injection amount calculation by the CPU 11.

The CPU 11 performs a predetermined calculation based on the sensor data fetched into the RAM 13 according to a control program stored in the ROM 12 in advance to obtain a fuel injection amount each time. This is a part for transmitting and receiving a communication message, which will be described later, and executing a predetermined diagnostic process specified through the message. The obtained fuel injection amount is given to the output circuit 15, and a signal corresponding to the obtained fuel injection amount is output from the engine control means 27 through the output circuit 15.
Is output to The engine control means 27 includes, for example, a fuel injection valve. In a diagnosis process described later, the sensor data taken into the RAM 13 in response to a RAM value continuous reading command from the diagnosis tool 5 is used by the CPU 1.
1, and the read data is output to the communication line 3 via the communication circuit 17 as diagnostic data.

When the diagnosis tool 5 needs to diagnose the vehicle-mounted electronic control device or the vehicle system therethrough, the diagnosis tool 5 is connected to the vehicle-mounted electronic control device (the example here) via the diagnostic connector 4 as described above. Is electrically connected to the engine control device 1 and the transmission control device 2 etc.), reads the data read as the diagnostic data, and supports the diagnosis of the data. The read diagnostic data is usually displayed as a list on a display or as a graph to inform the diagnostician whether or not the data is abnormal. The diagnostic connector 4 is supplied with power from a battery 19 via an ignition switch 18. When the diagnostic tool 5 is thus electrically connected to the on-vehicle electronic control unit, the diagnostic is performed via the diagnostic connector 4. Power is also supplied to the tool 5.

The diagnostic processing performed through the communication system according to the present embodiment includes, for example, R through the input circuit 14 and the AD converter 16 in the running state of the vehicle.
The sensor data (a value obtained by converting the output signal of each sensor into a physical quantity by the arithmetic processing by the CPU 11) taken into the AM 13 is read out to the diagnostic tool 5,
A so-called R for diagnosing whether the sensor data is normal or not.
There is an AM value continuous reading diagnosis. In the case of the RAM value continuous reading diagnosis, in order to diagnose an instantaneous abnormality of the sensor data and accurately trace the output of the sensor data through the diagnosis tool 5, the RAM 13 is rapidly and periodically fixed. It is necessary to read these sensor data continuously from the. For this reason, in the communication system of this embodiment, for the electronic control device designated as the object of the diagnosis, the time for performing the diagnosis, that is, the diagnosis continuation time information for notifying the diagnosis continuation time in advance, specifies the RAM value continuous reading diagnosis. It is incorporated in control commands so as to refrain from sending commands to these electronic control units while the RAM values are continuously read by the electronic control units.

FIG. 2 is a time chart showing a communication procedure for a RAM value continuous reading diagnosis executed through the communication system of the embodiment. That is, as shown in FIG. 2A, this communication procedure first requests the RAM value continuous reading diagnosis as a control command to the engine control device 1, for example.
When a request message a designating the diagnosis continuation time is transmitted from the diagnostic tool 5 to the communication line 3, the engine control device 1 receives the request message a and, according to the content of the request message a, receives the request message a in FIG. (1) The sensor data is read from the crank angle sensor 21, the vehicle speed sensor 22, the throttle sensor 23, the air flow meter 24, the water temperature sensor 25, the O2 sensor 26, etc. Are sequentially read and transmitted to the communication line 3 as a response message b. (2) After a predetermined time t (for example, 16 ms), the RAM value at that time as the sensor data, that is, the RAM value updated at that time is transmitted as a response message c. (3) Then, after a predetermined time t (for example, 16 ms), the RAM value at that time is transmitted as a response message. Are repeatedly executed until the diagnosis duration set in the request message a is reached.

FIG. 3 shows a frame structure per message employed in the communication system of this embodiment to realize such a RAM value continuous reading diagnosis, and the request message and the response message constructed based on the frame structure. Are respectively shown.

In the communication system of this embodiment, a frame signal having the structure shown in FIG. 3A per message is exchanged between the diagnostic tool 5 and various electronic control units. Incidentally, in this frame signal, SO
F (start of frame) is a part indicating the head of the frame signal (message), and is a # following the SOF.
Three bytes from 0 byte to # 2 byte are header fields to which header information such as a request or response of the message, a transmission destination of the message, and a transmission source of the message is added. Eight bytes of # 3 to # 10 bytes following the header field are data fields in which the contents of the diagnosis request and the contents of the response are incorporated, and the # 11 byte following the data field is an error detection byte. In the communication system of this embodiment, the cyclic redundancy code CRC method is used for error detection, and this error detection byte is also generated and confirmed by the communication circuit 17 in hardware. And, in the same frame signal, EOF (end of frame) is
This part indicates the end of the frame signal (message). Note that the SOF and the EOF are usually constituted by bits or bit strings of a predetermined logic that can be identified to that effect.

In the system of the embodiment, a request message transmitted from the diagnostic tool 5 to various electronic control units has a configuration shown in FIG. 3B. That is, the header bytes of # 0 byte to # 2 byte include, for example, that the message is a request message. The source of the message is the diagnostic tool 5. The destination of the message is, for example, the engine control device. In the # 3 byte of the data field, a code indicating the type of the diagnostic mode is incorporated. For example, the RAM mode continuous reading diagnostic mode is incorporated, and the following # 4 byte and # 5 byte are included. The start address value of the RAM read start required for executing the diagnostic mode (RAM value continuous read diagnostic mode) is a high byte (H-B) and a low byte (L-B).
B), and information (range (number of data)) for which the same continuous reading is desired is incorporated in # 6 bytes. Then, # 7 byte and # 8 of the same data field
Information indicating the diagnosis duration described above is incorporated in the byte. The remaining # 9 bytes and # 10 bytes are subjected to a compression process to eliminate them when transmitting the same message, especially when there is no information to be embedded therein.

On the other hand, in the system of the embodiment, the response message transmitted from the various electronic control units to the diagnostic tool 5 has a configuration shown in FIG. That is, in the header bytes of # 0 byte to # 2 byte, for example, the message is a response message. The source of the message is, for example, the engine control device. The destination of the message is the diagnostic tool 5. The data field # 3 byte to #
The RAM value that has been successively read is placed as diagnostic data in 10 bytes.

FIGS. 4 and 5 show the processing procedure (reception / transmission procedure) of the diagnostic processing executed in the on-vehicle electronic control unit, for example, the engine control unit 1, on the premise of such a message configuration. Hereinafter, FIG.
The operation of the communication system of this embodiment will be described in further detail with reference to FIG.

Here, the processing shown in FIGS. 4 and 5 is a procedure stored in advance in the ROM 12 as a part of the control program for the CPU 11 shown in FIG. As described with reference to FIG. 2, it is started every 16 ms to execute the necessary diagnosis and data processing for constructing a response message.

The control program stored in the ROM 12 and executing a diagnosis process described below includes a "diagnosis counter", an "address counter", and a "transmission operation counter" as shown in FIG. In addition to the "data area" in which the sensor data is stored, the RAM 13 also includes a counter program that implements each counter function as software. It is assumed that a “head address storage area”, a “read range storage area”, a “diagnosis continuation time storage area”, and an “execution flag registration area” in each diagnosis mode are added together as shown in FIG.

At the start of the RAM value continuous reading diagnosis, an electronic control unit to be diagnosed (here, the engine control unit 1) and a diagnosis mode (here, RAM value continuous) are operated through the operation unit (keyboard) of the diagnostic tool 5. (Read-out diagnostic mode) RAM1 for sensor data (RAM value) desired to be diagnosed
3 (precisely, the data area), that is, the start address for starting the reading of the RAM value. • It is assumed that the reading range of the same sensor data (RAM value), that is, the desired range of diagnosis for the data is input. Then, a request message as shown in FIG. 3B is formed by the diagnostic tool 5 and transmitted to the communication line 3 via the diagnostic connector 4.

On the other hand, the engine control device 1 (electronic control device) starts the diagnostic processing program shown in FIGS. 4 and 5 every 16 ms as described above in response to the request message transmitted from the diagnostic tool 5 as described above. Then, the following processing for diagnosis and construction of a response message is executed.

First, in step 101, it is determined whether or not a request message has been issued from the diagnostic tool 5, and if it is determined that the request message has been issued, in the next step 102, the header field # 0 bytes to #
Three bytes of two bytes are sequentially received. Then step 1
In step 03, it is determined whether or not each byte value of the received header field is correct, that is, whether or not the request message has been issued to the engine control device 1 itself. If so, the process proceeds to step 104, and if not, the diagnostic process ends (FIG. 5).

In step 104, the # 3 byte in the data field is received, and in step 105, it is determined which diagnostic mode is specified. Thereafter, the process jumps to the processing routine of the determined diagnostic mode. If the RAM value continuous reading mode is designated, the processing jumps to steps 106 to 109. Other diagnostic modes include a diagnostic mode for reading out only a specific RAM value (step 200) or RA
There is a command value rewriting mode (step 300) in which the M value is rewritten to diagnose the vehicle control.

When the RAM value continuous reading diagnostic mode is designated as the diagnostic mode as in the example here, the request message # 4
When the byte and the # 5th byte are received, the head address (ADR) for reading the RAM value is stored in the “head address storage area” of the RAM 13. Next, in the subsequent step 107, the # 6 byte of the request message is received, and the range of the address (ADR) at which the reading is executed is stored in the "reading range storage area" of the RAM 13. In the next step 108, # of the request message
The 7th byte and the # 8th byte are received, and the specified diagnosis duration is stored in the “diagnosis duration storage area” of the RAM 13. In step 109, a flag for executing the RAM value continuous reading diagnosis is set in the “execution flag registration area” of the RAM 13. That is, the start of the RAM value continuous reading diagnosis is stored in the RAM 13.

Next, in step 110 of FIG.
First, it is determined whether or not the execution flag of the RAM value continuous reading diagnosis mode is set. If the execution flag is not set, the execution flag of another diagnosis mode is checked and the diagnosis is executed. If the execution flag of the RAM value continuous reading diagnostic mode is set, at step 111, the diagnostic counter (ROM12
It is determined whether the “diagnosis counter” program within the period has passed the diagnosis continuation time. And the diagnostic time has passed
Tei lever resets the execution flag of the RAM value continuous reading diagnostic mode at step 112, stops the transmission of the response message. This diagnostic counter is LS
B (least significant bit) is a counter of 1 sec, 1 s
ec and incremented by 10
It is assumed that the execution flag is cleared at the timing set in step 9.

From step 114 onward, processing for transmitting a response message is performed. In step 114, first, three bytes # 0 to # 2 of the header field are transmitted. As described above, this header indicates that the message is a response message. The source of the message is the engine control device 1 (ID code). The destination of the message is the diagnostic tool 5. Things. Step 115 is a process of transmitting the RAM value specified by the read setting address. By loop control from step 119 described later,
The RAM value of the address sequentially incremented in the next step 116 is also sequentially transmitted through this step 115. The increment of the address value in step 116 includes the address counter (ROM 1
2 "address counter" program) is used.

In step 117, since the data field according to the present embodiment is limited to 8 bytes per message, the number of the currently transmitted byte is determined in step 11 below.
9, the transmission operation counter (ROM 1
2 is a process for incrementing the “transmission operation counter” program in 2).

The process of the next step 118 is a process for determining whether or not the read setting address incremented in the above step 116 has exceeded the last address of the transmission range. The process moves to step 119. In step 119, if the count value of the transmission operation counter is within "8", the process returns to step 115, and the process of transmitting the RAM value of the sequentially incremented address is repeated. If it is determined in step 118 that the read setting address has exceeded the last address of the transmission range, the process jumps to step 120 and sets the read setting address (address counter) to the start address in the request message. Return to Then, in step 121, the transmission operation counter is cleared to "0", and the process exits from the series of processing routines.

The above processing is executed every 16 ms. In addition, after the second time, the process directly proceeds to the diagnosis mode execution flag confirmation processing in step 110 through step 101, and then the progress of the diagnosis continuation time is monitored through the diagnosis counter (step 111). At the same time, only the response message construction processing is repeatedly executed, and eventually, message exchange with the diagnostic tool 5 in the form shown in FIG. 2 is realized.

As described above, according to the communication system of this embodiment, a desired electronic control unit (engine control unit) can be used for an arbitrary time designated by the diagnostic tool 5 without using a conventional continuation command or the like. The diagnostic processing through 1) is continued. Since the continuation command and the like are not required, the electronic control unit can concentrate on the requested diagnosis processing, and the processing result of the continuous high-speed RAM value continuous reading diagnosis at a constant cycle is naturally obtained. It will be highly reliable. Also, of course,
Even if the diagnostic connector 4 that connects the external diagnostic device and the electronic control device (engine control device 1) is disconnected during the diagnosis, the diagnosis process by the electronic control device continues forever. Will not be executed. That is, when the designated diagnosis continuation time has elapsed, the diagnosis processing is automatically terminated. Note that an arbitrary time desired by the user of the diagnostic tool 5 is designated as the diagnosis continuation time. For example, a relatively long time of about 10 to 20 minutes is appropriate for the above-described RAM value continuous reading diagnosis and the specific RAM value reading diagnosis shown as step 200 in FIG. In the command value (RAM value) rewriting diagnosis shown in step 300, although it depends on the control target, a relatively short time of about several tens of seconds to several minutes is appropriate due to the property of directly rewriting the command value. It is.

By the way, in the communication system of the above embodiment, the request message transmitted from the diagnostic tool 5 is based on the frame configuration shown in FIG.
Although the configuration is as shown in (b), the message configuration including the frame configuration is merely an example. In particular, the arrangement and order of various types of information in the data field are arbitrary, and the "read range (#
6)), it is also possible to specify the "last address" of the RAM value to be read out. By the way, in the specific RAM value reading diagnosis shown as step 200 in FIG. 4, when the above “reading range” is specified, the range “1” is specified, and the range is specified as the “last address”. In this case, the same address value as the "read start start address n (# 4, # 5)" is specified. What is essential is that this request message has a configuration in which information for designating “diagnosis continuation time” is added in some form in addition to the specification of various request information related to the diagnostic processing.

In each of the electronic control units including the engine control unit 1, means for temporarily storing the “diagnosis continuation time” specified through the request message,
Means for monitoring the progress of the stored “diagnosis duration”, and until the “diagnosis duration” is reached.
What is necessary is just to have a function of repeating the designated diagnostic processing, and the processing procedure for that is not limited to the procedures illustrated in FIGS. 4 and 5.

In the communication system of the above embodiment, the communication protocol is J1 of the American Society of Automotive Engineers (SAE).
Although it is based on the 850 standard, it is not limited to this. For example, the communication system according to the present invention can be similarly applied to a communication method using a master / slave.

In the communication system of this embodiment, the bit format is J18 as shown in FIG.
Although it is assumed that pulse width modulation (PWM) based on 50 is used, this is arbitrary, and for example, a bit format as shown in FIG. 7 can also be used. That is, in the bit format shown in FIG.
For example, it is assumed that an 8-bit NRZ (non-return zero) data byte is used. A start bit of a logic low level is added at the head and a stop bit of a logic high level is added at the end thereof, so that the existence of the data byte can be identified.

[0043]

As described above, according to the present invention, the diagnosis processing through the desired electronic control unit is continued for an arbitrary time designated by the external diagnosis unit without using a continuation command or the like. Since the continuation command and the like are not required, the reliability of the continued diagnosis processing result is improved.

In addition, even if the connector for connecting the external diagnostic device and the electronic control device is disconnected during the diagnosis, the diagnostic process by the electronic control device is continuously performed endlessly. Never even.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a communication system for vehicle diagnosis according to the present invention.

FIG. 2 is a time chart showing a communication procedure of a RAM value continuous reading diagnosis executed through the communication system of the embodiment.

FIG. 3 is a diagram showing a frame configuration per message employed in the communication system of the embodiment to realize the above-described RAM value continuous reading diagnosis, and a message configuration of a request message and a response message constructed based on the frame configuration. It is a time chart shown respectively.

FIG. 4 is a flowchart illustrating a communication processing procedure of the electronic control device included in the communication system according to the embodiment, particularly a processing procedure related to a diagnosis process;

FIG. 5 is a flowchart showing a communication procedure of the electronic control device constituting the communication system of the embodiment, particularly a processing procedure relating to construction of a response message;

FIG. 6 is a time chart showing a bit format used in a pulse width modulation (PWM) method based on the American Society of Automotive Engineers (SAE) J1850.

FIG. 7 is a time chart showing a bit format example on the assumption that a data byte of the NRZ (non-return zero) system is used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine control device, 2 ... Transmission control device, 3 ... Communication line, 4 ... Diag connector, 5 ... Diagnostic tool, 11 ... CPU, 12 ... ROM, 13 ... RAM, 14
... input circuit, 15 ... output circuit, 16 ... AD conversion (AD
C) circuit, 17 communication circuit, 18 ignition switch, 19 battery, 21 crank angle sensor, 22
Vehicle speed sensor, 23: throttle sensor, 24: air flow meter, 25: water temperature sensor, 26: O2 sensor, 27
... engine control means.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q 9/00-9/16 H04L 12/40 B60R 16/00-16/02

Claims (2)

(57) [Claims] An electronic control device mounted on a vehicle is connected to an external diagnostic device via communication means.
A request message for requesting execution of a diagnostic process is transmitted to the selected electronic control device, and the selected electronic control device executes a specified diagnostic process in accordance with the received request message. In the communication system, the diagnostic device incorporates, in the request message, diagnostic duration information that specifies a duration of the diagnostic processing, and the selected electronic control device, after receiving the request message, The vehicle diagnostics is characterized in that the diagnostic processing is executed until the time specified by the diagnostic duration information is reached, and the diagnostic processing being executed is terminated by reaching the time specified by the diagnostic duration information. Communication system. 2. An electronic control device mounted on a vehicle is connected to an external diagnostic device via a communication means.
A request message for requesting reading of the control data is transmitted to the selected electronic control device, and the selected electronic control device returns the read control data as a response message in response to the received request message. In the communication system for vehicle diagnosis, the diagnosis device incorporates, in the request message, diagnosis duration information that specifies a duration required for reading the control data, the selected electronic control unit transmits the request message. Until the time specified by the diagnostic duration information is reached, the read control data is repeatedly returned to the diagnostic apparatus while incorporating the read control data in the response message, and the read control data is specified by the diagnostic duration information. The reply of the response message is terminated when the time reaches Communication system for a vehicle diagnostics.