JP3065651B2 - Data communication method in in-vehicle communication network - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data communication method in a vehicle-mounted communication network, and more particularly to a data communication method suitable for use in a connection network of a vehicle-mounted AV (audio-visual) system. Related to the communication method.

[Conventional technology]

In recent years, in-vehicle audio systems have evolved from systems that merely listen to music to systems that include visual elements. A system having not only audio but also visual functions is known as an AV system.

In-vehicle AV systems are constructed with various elements. For example, the audio element includes a cassette tape deck, a radio tuner, a CD (compact disk) player, and the like, and the visual element includes a TV.
(Television) A tuner, a navigation device, and the like are included. An audio reproduction signal output from each of these elements is reproduced from a speaker mounted in the vehicle via an amplifier, and an image reproduction signal is similarly output as an image on a display mounted in the vehicle. Today, each of these elements is controlled by digital technology, which is controlled by a microcomputer-based controller.

In order to operate each of the above elements systematically,
It is necessary to control each element comprehensively. Therefore, in the on-vehicle AV system, the controllers of the above elements are connected by a bus network, and mutual control data is transmitted and received via a communication bus constituting the network.

In a conventional network, each controller is controlled by a polling method. The polling method is a method in which one of the controllers is given a priority position, the controller is set as the master, and the remaining controllers are set as the master-slave relationship, and the master is always used when the master collects data from the slave. This is a method for accessing the slave side from the server.

When the master transmits and accesses communication data to the slave by the conventional polling method, or when the slave returns data to the master, it is necessary to identify or specify each controller. Therefore, an address indicating the controller is assigned to each controller.

In the conventional address assignment method, a unique address is assigned to each controller. And
The control data is generated with address data unique to each controller added with instruction data (for example, a start command: ON data) for the controller, and sent out on the communication bus.

[Problems to be solved by the invention]

The problem with the conventional connection network is that a polling method is used for transmitting and receiving communication data.
That is, especially in the case of an in-vehicle AV system, the power supply is turned ON / OFF each time the ACC switch (car accessory power supply switch) linked to the engine switch is turned ON / OFF. It is necessary to check the connection status of the slave device. In this case,
According to the polling method, every time the ACC switch is turned on, the master device must access each slave device for confirming the connection, and the burden on the master device is extremely large. For example, when the address of the slave device is 12 bits, if the connection is confirmed by the serial poll of the master device, up to 4096 accesses are required.

In addition, in the case of the polling method, in order for the master device to access the slave device, the master device needs to register the addresses of all the slave devices on the communication bus. No access can be made to the communication bus, and even if it is physically or electrically connected to the communication bus, it does not function. In order to function reliably, a procedure for assigning a unique address to the additional slave device and newly registering it is necessary.

An object of the present invention is to provide a data communication method in a vehicle-mounted communication network that can achieve a reduction in the burden on a master device and an improvement in expandability of an AV system.

[Means for solving the problem]

In order to solve the above-mentioned problem, the invention according to claim 1 comprises, as shown in FIG. 1 (a), one master device (M) and one or more slave devices (S).
Is a data communication method in a bus-type in-vehicle communication network connected to the same communication bus (B),
As shown in FIG. 1 (b), the master device (M)
Connection request information (D _REQ ), which is connection request information from the slave device (S) and includes slave identification information indicating the slave device (S) and master identification information indicating the master device (M), has been received. After that, the connection status information (D _CON ) on the other slave device (S) connected to the communication bus (B) is transmitted to the slave device (S) that transmitted the connection request information (D _REQ ). Then, connection state information (D _CON ) including the master identification information and the slave identification information indicating the slave device (S) that has transmitted the connection request information (D _REQ ) is issued.

According to a second aspect of the present invention, in the data communication method in the on-vehicle communication network according to the first aspect, the slave device (S) indicates the slave device (S) itself as the slave identification information. The connection request information (D _REQ ) including slave device identification information and slave function identification information indicating the function of the slave device (S) is transmitted.

Further, according to a third aspect of the present invention, in the data communication method in the vehicle-mounted communication network according to the second aspect, the master device (M) indicates the master device (M) itself as the master identification information. The connection status information (D _CON ) including master device identification information and master function identification information indicating a function of the master device (M) is issued.

[Action]

According to the first aspect of the present invention, as shown in FIG. 1 (b), the master device (M) receives the connection request information (D _REQ ) from the slave device (S) only ( STEP
1) issue connection state information (D _CON ) of another slave device (S) connected to the communication bus (B) (STEP 2),
The master device (M) does not actively access the slave device (S). In other words, information is provided after waiting for a self-report from each slave device (S). As described above, by adopting the self-reporting method from the slave device (S), the load required for the access of the master device (M) is reduced.

In addition, since the slave device (S) actively reports itself, even if there is an additional connection of a new slave device (S) not registered in the master device (M), after the declaration, the system is set up. Can function as a member.

Further, the master device (M) having received the connection request information (D _REQ ) transmits the connection state information (D _CON ) relating to the other slave devices (S) connected to the communication bus (B) to the connection request information (D _REQ). ) Is transmitted to the slave device (S) that issued the command, all the slave devices (S) have the connection information of the communication bus (B).

In the operation of providing the connection state information (D _CON ), the slave device (S) transmits the connection request information (D _REQ ) including the slave identification information and the master identification information, and the master device (M) transmits the connection request information. After receiving (D _REQ ), it issues connection state information (D _CON ) including master identification information and slave identification information indicating the slave device (S) that transmitted the connection request information (D _REQ ).

Therefore, when returning the connection state information (D _CON ) from the master device (M) as the transmission destination to the slave device (S) as the transmission source of the connection request information (D _REQ ),
The reply can be reliably executed by quickly recognizing the slave device (S).

Further, even when a new slave device (S) is connected to the communication bus, the connection request information (D _REQ ) from the slave device (S) is immediately recognized by the master device (M). The addition of a new slave device (S) can be easily and quickly recognized in the master device (M), and the master device (M) can be recognized.
, The new slave device (S) can be immediately recognized, so that the master device (M) can quickly start processing corresponding to the new slave device (S).

Further, even when the existing slave device (S) is dropped, the master device (M) can immediately recognize which slave device (S) has dropped, and in the master device (M). The process corresponding to the drop of the slave device (S) can be started quickly.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, a connection request in which the slave device (S) includes slave device identification information and slave function identification information as slave identification information. Since the information (D _REQ ) is transmitted, for example, a new slave device (S) is connected to the communication bus (B).
In this case, the function of the new slave device (S) can be reliably recognized in the master device (M).

According to a third aspect of the present invention, in addition to the operation of the second aspect, the connection state in which the master device (M) includes master device identification information and master function identification information as master identification information. Since the information (D _CON ) is issued, for example, when a new slave device (S) is connected to the communication bus (B), the function of the master device (M) in the new slave device (S) is ensured. Can be recognized.

〔Example〕

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

Power supply system of AV system The present invention is preferably applied to a vehicle-mounted AV system. As shown in FIG. 2, the AV system 103 receives power supply from the car battery 101 via the ACC switch 102. The ACC switch 102 is a switch that is linked to an engine key of the vehicle. By rotating the engine key to the position of the ACC switch 102, power is supplied to accessories in the vehicle. Therefore, in general, the power supply to the AV system 103 is repeatedly turned on / off each time the engine key is turned.

Example of Configuration of AV System FIG. 3 shows an example of the configuration of an AV system to which the present invention is applied. In the example of FIG. 3, a tape deck 6 for reproducing a recording signal from a cassette tape 1, a tuner 7 such as an FM for reproducing a radio wave received by an antenna 2, and a CD player for reproducing a recording signal from a CD 3 are used as an audio reproducing apparatus. 8
And a multi-CD player 9 including an auto-changer 5 for reproducing a recording signal from each CD of the multi-CD 4.
As the visual playback device, the TV received by antenna 2
A TV tuner (assumed to be built into the tuner 7) for reproducing radio waves or a CD-ROM 8
And a display 12 for outputting the recorded still image via the CD player 8. CD-RO
A typical example of using M is a navigation device. The external commander 10 includes a keyboard for inputting various operation commands from outside. The input device 13 can also be incorporated in the external commander 10.

Each of the above devices has a controller for controlling its own operation, and the controllers are connected to each other via a communication BUS 14 to form a bus control network. The structure of this network is shown in FIG. 4, and the details will be described later.

On the other hand, the reproduced signal of the audio reproducing apparatus is selectively input to the digital amplifier 16 via the selector 15 and is amplified by a predetermined amount and then emitted from the speaker 17. A digital signal circuit included in the digital amplifier 16 is also controlled by a built-in controller, and this controller is also connected to the communication BUS.

AV System Control Network FIG. 4 shows an example of an AV system control network. Here, for convenience of explanation, in FIG.
Each device connected to S14 is referred to as a “unit” as a general expression. As shown in FIG. 4, each unit is connected to the communication BUS 14 in parallel. One of the units is referred to as a “master” in order to control the network in general, and this is indicated by a master unit 200. Are all other remaining units "slave", these slave units 200 _-1 to 200
Shown by _-n .

Master controller 1 built in master unit 200
8 is connected to the communication BUS 14 via the communication interface IC25. In this example, the master controller 18 also controls the tape deck 6 and the tuner 7. Further, the control section of the tape deck 6 of the master controller 18 also controls the autochanger 5. Slave unit 200 _-1 to 2
Each of the slave controllers 19 to 24 built in 00- _n is similarly connected to the communication BUS 14 via the communication interface ICs 25 to 31.

FIG. 5 shows the master unit 200 and the slave unit 200.
A specific example of the connection state with _-n is shown. As shown in FIG.
Communication BU between master unit 200 and slave unit 200- _n
Connected by S14. The communication BUS 14 uses a twisted pair line composed of two lines. The communication data DT transmitted and received via the communication BUS 14 is transmitted to the communication interface IC 25 of the master unit 200 and the slave unit 200- _n.
And the communication interface IC31. The communication interface IC 25 is a communication driver / receiver 32
Similarly, the communication interface IC31 is separated into a communication driver / receiver 35 and a communication control IC36. In this regard, in the related art, it has been provided integrally in one IC. The communication control IC 33 is formed of a COMS transistor and has a communication driver /
The receiver 32 is formed of a bipolar transistor having a high current driving capability. The same applies to the communication driver / receiver 35 and the communication control IC 36.

Thus, regarding the communication interface IC 25, the communication control IC 33 and the communication driver / receiver 32
This makes it possible to cope with a change in the transmission medium of the communication BUS 14. For example, in the example of FIG.
Although a twisted pair wire is used as the communication BUS 14 for differential transmission, as shown in FIG. 6, when an optical communication cable 40 is used as the communication BUS 14, a communication driver / receiver
By using the electro-optical converter 38 instead of 32, it is possible to cope without changing other configurations. Further, the operation failure generated in the master unit 200 is largely due to disturbance noise mixed in from the communication BUS 14, and even if an excessive signal is mixed in for some reason, the communication driver / receiver 32 alone often fails. /
By replacing only the receiver 32, it is easy to return to the current state, which is advantageous for maintenance. In particular, for automotive
In the case of an AV system, it is effective because there are many machines mixed with noise generated from the engine system of a car.

Also, from the viewpoint of IC manufacturing, it is easier to manufacture the IC and the cost is more advantageous if the CMOS transistor and the bipolar transistor having different manufacturing processes are separated from each other than the configuration of the Bi-CMOS IC. .

Incidentally, the above description has described a communication interface IC 25, and is separated into a communication driver / receiver and the communication control IC Similarly for communications interface IC26~31 the other slave units 200 _-1 to 200 DEG _-n.

Next, the transmission format of the communication data DT used in the present invention will be described.

FIG. 7 shows an example of a transfer format of the communication data DT. As shown in FIG. 7, the communication data DT, the master address data MA from the head indicates the address of the master unit 200, slave address SA indicating the addresses of the slave knit 200 _-1 to 200 DEG _-n, the message length of data D It comprises message length data N, classification data TP indicating the type of data D, and data D indicating transfer contents.

The configuration of the data D is the content of the communication data DT,
It differs depending on the classification data TP, and is roughly classified into three types of format configurations. As shown in FIG. 10, the first format is a format for confirming connection, the second format is a format for keys, display data, and the like, and the third format transmits a result of a checksum CS. Format. Furthermore, the format for confirming the connection is to transfer the communication data DT to the slave units _200-1 to 200-2.
The transfer from 00 _-n to the master unit 200 is different from the transfer from the other unit. In FIG. 10, the format of the key and the display data is the same from the physical status data PS to the logical mode data LM in the data configuration, and is not shown.

The classification data TP is a data area which is arranged at the head of the communication data DT and indicates the type of data D following the classification data TP. The classification data TP is composed of large classification data and small classification data. The Oita data, as shown in FIG.
Indicates the type of data D. Bit allocation is classified data TP
If the whole is 8 bits, the upper 4 bits are assigned. As shown in FIG. 9, the small classification data is mainly used to identify the format of the data D, and the lower 4 bits are allocated.

Physical address data PA is Figure 11, as shown in FIG. 12, the communication interface of the master unit 200 to slave unit 200 _-1 to 200 DEG _-n on the communication BUS 14 IC25～
This is an address in communication for specifying 31 and is an address indicating the master unit 200 and the slave units 200 _-1 to 200 _-n . Of the physical address data PA, the physical address data PA that specifies the master unit 200 is always fixed. As for the physical address data PA, basically, one physical address data PA is assigned to one unit. FIG. 14 shows an example in which physical address data PA is allocated in association with the unit configuration shown in FIG. In addition,
In FIG. 14, physical address data PA is also set in the master controllers 18 to 24. This is because, like the master unit M, two functional elements of the tape deck 6 and the tuner 7 are provided in one controller master controller 18. Is connected. In a combination of one function for one controller, the physical address data PA and the logical address data LA have the same address as in the slave controllers 19 to 24.

Physical status data PS, the master unit M, a status information about the unit of the slave units S ₁ to S _n, functional address to which the unit has (ie, the logical address data LA, described below) with data indicating the number of is there.

The logical address data LA, as shown in FIG. 13 is data indicating the master unit M, the slave unit S ₁ to S _n the unit functions of the (i.e., tuner, that the tape deck), every function Assigned to
The number of the logical address data LA is the physical address data PA
LA ₁ and L as many as the functions assigned to the controller determined by
It is not a fixed number because it is added as A ₂ .
FIG. 14 shows an example in which logical address data LA is allocated in association with the unit configuration in FIG.

The talker address data TL indicates the address of the transmission source (speaker) transmitting the communication data DT.

The listener address data LN indicates an address of a transmission destination (listener) for receiving the communication data DT.

The logical status data LS contains each logical address.
Indicates the state of the function corresponding to LA.

The logical mode data LM indicates an operation state (mode) of a function corresponding to each logical address.

The checksum data CS is data for error detection added in order to improve the reliability of the data D.

Communication operation In the AV system described above, the master unit M
To explain the operation when the following communicating communication data DT between the slave units S ₁ to S _n.

In this network, unlike the conventional polling method, all slave units self-declare their own units to the master unit. The master unit does not actively access the slave unit.

That is, the connection confirmation sequence in the present invention is roughly divided into the communication sequence SEQ when the power is ON (ACC switch ON).
₁ and communication sequence S during power supply period (during normal operation)
Consisting of EQ ₂ Metropolitan.

(1) The basic algorithm of the communication sequence SEQ ₁ when the power is turned on is as follows (for the detailed algorithm, see FIGS. 15 (a) and 15 (b)).

"Each slave detects access to the power supply and then accesses the master and requests connection confirmation. The master sets the slave that has accessed it as the connected slave, and after a predetermined time elapses,
Provide information to each slave. (2) The communication sequence SEQ ₂ during the power supply period is
Slave units S ₁ to S _n processing sequence SEQ ₃ during separation of
New slave unit S _m processing sequence at the time of participation of the
SEQ ₄ and their basic algorithms are as follows (detailed algorithm is shown in FIG. 16 (a),
(B)).

(2-1) Processing sequence at the time of dropout SEQ ₃ “Each slave sends a connection confirmation request to the master at regular intervals. In contrast, the master always provides the latest connection information. For slaves that have not received a connection confirmation request, it is considered that they have been dropped off from the BUS, and necessary internal processing is performed, and to that effect (the latest connection information is provided.) (2-2) Processing sequence when joining SEQ ₄ "If the slave whose connection has not been confirmed in the connection confirmation at power-on suddenly requests a connection confirmation, it is deemed to have joined, and necessary internal processing is performed. And providing the (latest) connection information to that effect to each slave. ”As described above, when the slave accesses the master and makes a connection request, the master is connected to the communication bus. Information about the configuration of the slaves, that is, the latest connection information is provided.Since this information is provided to all slaves that have requested connection, all slaves share the same connection information. You are doing.

FIG. 17 shows a specific example of this state. As shown in FIG. 17, the slave unit _200-1 transmits a connection request information DT ₁ to the master unit 200, the master unit 200 issues the connection information DT ₂ to the slave unit 200 _-1. Similarly, for slave unit _200-2 , connection request information DT ₂
Sending connection information DT ₂ is sent from the master unit 200. Since performing this operation on all the master units 200 _-1 to 200 DEG _-n, all master units 200 _-1 to 200 DEG _-n will share the same connection information DT _2. In other words, communication bus 1
This means that all the slave units 200 _-1 to 200 _-n on 4 know the configuration of the device (or function) of the AV system. As a result, master unit 200 and slave unit 2
Instead of a one-to-one relationship with 00 _-1 to 200 _-n , the individual slave units 200 _-1 to 200 _-n can directly communicate with each other. This means that even if the master unit 200 fails for some reason, any one of the slave units 200 _-1 to 200 _-n can have an alternative function of the master unit 200. .

Next, a specific example is shown in FIG. FIG. 18 shows an example of a connection confirmation sequence when a slave unit including a TV / FM tuner and a master unit perform access confirmation access to their own AV system from the slave unit side.

Now, in FIG. 18, because the slave unit is connected confirmation request (self-reported), to transmit to the master unit via the communication BUS14 issue the communication data DT _1. At this time, the communication data DT ₁ sets its own physical address data PA to “1”.
23H "(H is hexadecimal hexadecimal), the physical address data PA of the master unit of the other party is set to" 100H ", and the logical address data indicates that its own slave unit has a configuration including a TV tuner and an FM / AM tuner. This is indicated by LA ₁ = 05 and logical address data LA ₂ = 07 (see Fig. 11.) This communication data DT ₁ allows the master unit M to have PA = 123H and LA ₁
It is registered that a device having the functions of = 05 and LA ₂ = 07 has been connected to the communication BUS 14, and this device will be treated as an AV system member thereafter. Master unit, when the communication data DT ₁ is sent to indicate that it has received the communication data DT _1, and returns the return data RDT ₁ to the slave unit. Then, the slave unit which is newly connected, for notify the constituent members of the AV system, and transmits the system connection information DT ₂ to the slave unit side. The slave unit that has received the system connection information DT ₂ for acknowledgment, and returns the return data RDT ₂ to the master unit side. Then, after a predetermined time has elapsed, the slave unit transmits a connection confirmation request communication data DT ₁ of (self-reported) to the master unit side again. In the case of an in-vehicle AV system, the transmission of the connection confirmation request communication data DT ₁ again after the predetermined time has elapsed is performed when the power supply is turned ON / OFF.
This is because it depends on the ON / OFF of the ACC switch, so it is necessary to check the connection periodically.

As described above, the communication data DT always includes the physical address data PA and the logical address data LA, and the physical address data PA and the logical address data LA are mutually independent data. The communication data DT can be transmitted to any destination.

In the above operation example, an example of communication between the slave unit and the master unit has been described, but communication can be similarly performed between other slave units.

In addition, the format of the communication data DT and the address assignment to each unit
And the logical address LA, it is possible to connect a new unit if the logical address LA is clearly set even if the physical address PA is unknown. Communication between the unit and the already connected unit is possible.

That is, it is assumed that a new slave unit 200 _- m is connected to the communication BUS 14 as shown in FIG. In this case, even if the physical address data PA of the slave unit 200- _m is not assumed and the physical address data PA is 101, if the function is the “display function”, it is already registered in the slave unit 200. Since the same function exists with the logical address data LA = 01, the logical address data LA can be accessed, so that the slave unit 200- _m can be connected. This means that A
This will contribute to improving the scalability of the V system.

〔The invention's effect〕

As described above, according to the first aspect of the present invention, since the connection confirmation of each slave device to the communication bus is performed by self-report from each slave device, the master device polls each slave device. This eliminates the need to perform the operation, and reduces the burden on the master device. Even if the address of the slave device is not registered on the master device side, it can be easily added by self-declaration, improving the expandability of the AV system and free connection. The degree of improvement is ensured.

Further, in the operation of providing the connection state information, the slave device transmits the connection request information including the slave identification information and the master identification information, and the master device transmits the master identification information and the connection request information after receiving the connection request information. Since the connection state information including the slave identification information indicating the slave device that has been issued is issued, when the connection destination information is returned from the master device as the transmission destination to the slave device as the transmission source of the connection request information, The reply can be surely executed by quickly recognizing the slave device.

Furthermore, even when a new slave device is connected to the communication bus, the connection request information from the slave device is immediately recognized by the master device, and the fact that the new slave device has been added is indicated by the master device. And the master device can immediately recognize a new slave device, so that the master device can quickly start processing corresponding to the new slave device. .

Also, when an existing slave device is dropped, which slave device is dropped can be immediately recognized by the master device, and processing corresponding to the drop of the slave device can be quickly performed by the master device. You can start.

Further, according to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the slave device transmits connection request information including slave device identification information and slave function identification information as slave identification information. Therefore, for example, when a new slave device is connected to the communication bus, the function of the new slave device can be reliably recognized in the master device.

Furthermore, according to the invention described in claim 3, according to claim 2,
In addition to the effects of the invention described in the above, since the master device issues connection state information including master device identification information and master function identification information as master identification information, for example, when a new slave device is connected to the communication bus In this case, the function of the master device can be reliably recognized in the new slave device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a power supply system diagram of an AV system, FIG. 3 is an overall configuration diagram of the AV system, FIG. 4 is a block diagram of a control network of the AV system, and FIG. FIG. 6 is a block diagram showing a specific example of a connection state between a master unit and a slave unit. FIG. 6 is a block diagram showing another example of a connection state between a master unit and a slave unit. FIG. 7 is an explanatory diagram showing a transfer format of communication data. , FIG. 8 is an explanatory diagram showing the contents of the classification data (major classification), FIG. 9 is an explanatory diagram showing the contents of the classification data (small classification), FIG. 10 is an explanatory diagram showing the basic data format, FIG. Is an explanatory diagram showing an example of a physical address, FIG. 12 is an explanatory diagram showing an example of a physical address, FIG. 13 is an explanatory diagram showing an example of a logical address, and FIG. 14 shows an example of allocation of a physical address and a logical address. Block Diagram FIG. 15 is a flowchart showing a communication sequence at the time of power-on, FIG. 16 is a flowchart showing a communication sequence during a power supply period, FIG. 17 is an explanatory diagram of a transmission state of system connection information, and FIG. FIG. 19 is an explanatory diagram showing an example, and FIG. 19 is a block diagram when an additional slave unit is connected. ADR… Address data B… Communication BUS CS… Check sum data D… Data DT… Communication data DT ₁ … Connection confirmation request information DT ₂ … System connection information LA, LA _{1 to} LA _n … Logical address data M ...... master device PA, PA ₁ ~PA _n ...... physical address data PS ...... physical status data S ₁ to S _n ...... slave device TP ...... classification data 101 ...... car battery 102 ...... ACC Switch 103 AV system 200 Master unit 200 _-1 to 200 _-n Slave unit 1 Cassette tape 2 Antenna 3 CD 4 Multi CD 5 Auto changer 6 Tape deck 7 Tuner 8 CD player 9 Multi CD player 10 External commander 11 Display 12 Display 13 Input device 14 Communication BUS 15 Selector 16, 16A Digital Amplifier 17 Speaker 18 Master controller 19 Slave controller 20 Slave controller 21 Slave controller 22 Slave controller 23 Slave controller 24 Slave controller 25 Communication interface IC 26 Communication Interface IC 27 Communication interface IC 28 Communication interface IC 29 Communication interface IC 30 Communication interface IC 31 Communication interface IC 32 Communication driver / receiver 33 Communication control IC 34 Controlled Unit 35 Communication driver / receiver 36 Communication control IC 37 Controlled unit 38 Electrical / optical converter 39 Electrical / optical converter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshiyuki Kimura 25-1, Nishimachi, Yamada, Kawagoe-shi, Saitama Prefecture Pioneer Corporation Kawagoe Factory (56) References JP-A-2-130049 (JP, A) JP-A Sho 62-111545 (JP, A) JP-A-62-292543 (JP, A) JP-A-63-9251 (JP, A) JP-A-63-215239 (JP, A) JP-A-4-4636 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/00 H04L 12/28 H04L 12/40-12/44 H04Q 9/00

Claims (3)

(57) [Claims] 1. A data communication method in a bus-type vehicle-mounted communication network in which one master device and one or more slave devices are connected to the same communication bus, wherein the master device is the slave device. After receiving connection request information including connection identification information indicating the slave device and master identification information indicating the master device from the connection request information, the slave device transmitting the connection request information, Issuing connection state information relating to other slave apparatuses connected to the communication bus, the connection state information including the master identification information and the slave identification information indicating the slave apparatus that has transmitted the connection request information. A data communication method in a vehicle-mounted communication network. 2. The data communication method in a vehicle-mounted communication network according to claim 1, wherein the slave device includes, as the slave identification information, slave device identification information indicating the slave device itself, and a function of the slave device. Slave function identification information,
A data communication method in a vehicle-mounted communication network, characterized by transmitting the connection request information including: 3. The data communication method according to claim 2, wherein the master device includes, as the master identification information, master device identification information indicating the master device itself, and a function of the master device. A data communication method in a vehicle-mounted communication network, comprising issuing the connection state information including master function identification information.