JP2005191910A - Communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication method equalizing the communication loads of CPUs of respective units and efficiently performing communication. <P>SOLUTION: The communication unit of a transmission origin provides a first/end flag F/E_F indicating the start and end of data transmission and S_ID indicating the ID data of the transmission origin in a communication frame 61 and transmits it to the communication unit of a transmission destination. At the time of receiving the first/end flag F/E_F indicating the start and end of the data transmission, the communication unit of the transmission destination transmits response frames 62 and 63 indicating reception establishment corresponding to flag data and including T_ID indicating the ID data of the transmission origin to the communication unit of the transmission origin. The communication unit next in the order of the ID data detects that the response frames 62 and 63 corresponding to the first/end flag F/E_F indicating the end of the data transmission are transmitted from the communication unit of the transmission destination, and transmission and reception are successively performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to the technical field of a communication method performed using a serial communication line between a plurality of communication units.

Conventionally, half-duplex communication using a serial communication line consists of a master unit and a slave unit. The master unit designates the slave and transmits data. Send data when you are specified. The slave unit does not voluntarily send data, but sends data only when designated by the master (see, for example, Patent Document 1).
JP 2001-251319 A (page 2-5, full view)

However, in the conventional communication method, since the master always calls the slave, the load on the CPU of the master unit increases.
In addition, since the data must be transmitted once to the slave via the master, the slaves cannot communicate with each other, and the responsiveness is poor via the master.

The present invention was made paying attention to the above-mentioned problems, and the object is as follows.
It is an object of the present invention to provide a communication method capable of equalizing the communication load of the CPU of each unit and performing communication efficiently.

  In order to achieve the above object, according to the present invention, in a communication method in a network configured by connecting a plurality of communication units in a bus form with serial communication lines, a non-overlapping ID is assigned to each communication unit, and the communication unit of the transmission source Provides a flag indicating the start and end of transmission in the data, and when the destination communication unit receives the data including the flag indicating the end of data, the communication unit of the transmission source includes the ID of its own unit, Response data indicating that it has been received is transmitted.

  Therefore, in the present invention, the communication load of the CPU of each communication unit can be equalized, and communication of each communication unit can be performed efficiently.

  Hereinafter, embodiments for realizing the communication method of the present invention will be described based on claims 1, 2, and 3.

First, the configuration will be described.
FIG. 1 is a diagram illustrating a configuration of a communication system using the communication method according to the first embodiment. FIG. 2 is an explanatory diagram illustrating a format of communication data used in the communication method according to the first embodiment. FIG. 3 is a flowchart showing a flow of transmission processing executed in the communication unit of the communication system using the communication method of the first embodiment. FIG. 4 is a flowchart illustrating a flow of reception processing executed by the communication unit of the communication system using the communication method according to the first embodiment. FIG. 5 is an explanatory diagram illustrating a communication procedure of the communication method according to the first embodiment. FIG. 6 is a timing chart illustrating the communication timing of the communication method according to the first embodiment. FIG. 7 is an explanatory diagram illustrating a communication state of the communication method according to the first embodiment.

The communication system using the communication method of the first embodiment is configured by serial communication with an in-vehicle device mounted on a vehicle. As shown in FIG. Are connected in a bus form. In the first embodiment, for the sake of explanation, a case where there are three communication units (partially four) will be described.
Each communication unit 1, 2, 3 includes CPUs 11, 21, 31 that perform data processing and communication control, transmission circuits 12, 22, 32 that convert data output from each CPU n1 and output the data to the communication line 5, and communication lines 5 is constituted by receiving circuits 13, 23, and 33 that convert the signal from 5 and output it to each CPU n1.

Next, the communication format 6 used in the communication method of the first embodiment will be described with reference to FIG.
The communication frame 61, which is data expressed in a frame format, is a LENGTH indicating the data length, an S_ID indicating the ID number of the own station, a T_ID indicating the ID number of the partner station, and a first / end flag F indicating the start and end of data transmission. / E_F, data DATAn (DATA1 to DATAn), and a checksum SUM for verifying consistency between transmission data and reception data.

The response frame 62 transmitted to indicate the completion of normal data transmission is composed of an ACK indicating the completion of normal data transmission and a T_ID indicating the ID number of the partner station or an end flag E_F indicating the end of transmission data. The
The response frame 63 transmitted to indicate incomplete data transmission is composed of a NACK indicating incomplete data transmission and a T_ID indicating the ID number of the partner station or an end flag E_F indicating the end of transmission data. The

  Next, the operation will be described.

[About master / slave communication method]
Regarding the master / slave communication method, FIGS. 8 to 14 show the configuration, the format of communication data, the flow of transmission processing and reception processing, the communication procedure, and the time chart.
First, the flow of communication processing on the master side in the master / slave communication method will be described using the flowchart shown in FIG.

  In step S101, a process for setting the ID number of the slave unit to 1 is performed.

  In step S102, data transmission for requesting data is performed to the slave unit set in the slave ID number.

  In step S103, the timer count of timer T3 is started.

  In step S104, it is determined whether or not the data of the slave unit set in the slave ID number has been received. If received, the process proceeds to step S105. If not received, the process proceeds to step S107.

  In step S105, the slave ID number is incremented (+1).

  In step S106, it is determined whether or not the slave ID number is the maximum value. If it is the maximum value, the process proceeds to step S101, and if it is not the maximum value, the process proceeds to step S102.

  In step S107, it is determined whether the counted timer has elapsed time T3. If T3 has elapsed, the process proceeds to step S108, and if T3 has not elapsed, the process proceeds to step S104.

  In step S108, it is determined whether the timeout is the first time with the same slave ID number. If it is the first time, the process proceeds to step S102, and if it is not the first time (multiple times), the process proceeds to step S105.

  Next, the flow of the communication method on the slave side of the master / slave communication method will be described using the flowchart shown in FIG.

  In step S111, it is determined whether data has been received. If received, the process proceeds to step S112, and if not received, the process proceeds to step S111 to wait.

  In step S112, it is determined whether the received data is directed to the own unit. If the received data is directed to the own unit, the process proceeds to step S113. If not, the process proceeds to step S111.

  In step S113, the data of the own unit is transmitted to the master unit.

In the following explanation, it is assumed that there are four slave units.
In the master / slave communication method, as shown in FIG. 12, all communication is performed by communication of the slave units S1 to S4 with respect to the master unit M. Therefore, as shown in FIG. 9, the communication frame Fm used in the master unit M has only the other party, that is, the slave unit with T_ID, and the communication frame Fs used in the slave units S1 to S4 has the own unit, that is, the slave with S_ID. You will only have units.

In this master / slave communication system, the master unit is also used in normal communication processing (see FIG. 13A, steps S101 to S106 in FIG. 10, S111 to S113 in FIG. 11), and retransmission processing (see FIG. 13B). And communication between slave units.
As described above, in the master / slave communication method, all communication is performed between the master unit and the slave unit. Therefore, the greater the number of slave units, the greater the load on the master unit. Further, since all communication is performed via the master unit, the efficiency is not good.
In particular, in-vehicle devices have advanced CPU performance of each in-vehicle device due to intelligentization. If a slave unit is used, the CPU performance of each device cannot be fully utilized. Regardless of this, in this communication method, the load on the master unit increases.
In this regard, in the first embodiment, the load is equal.

[Transmission process]
FIG. 3 is a flowchart showing a flow of transmission processing executed by the CPU n1 of each of the communication units 1, 2, 3, 4 by the communication method of the first embodiment. Each step will be described below.

  In step S11, transmission processing is started.

  In step S12, a transmission partner is set according to the necessity of the communication unit.

  In step S13, transmission data for the set transmission partner is set.

  In step S14, the transmission timer starts counting.

  In step S15, it is determined whether the count time of the transmission timer has reached T1, and if T1 is reached, the process proceeds to step S18, and if not, the process proceeds to step S16.

  In step S16, it is determined whether or not ACK data indicating that normal data reception was performed. If received, the process proceeds to step S17. If not received, the process proceeds to step S21.

  In step S17, the process ends.

  In step S18, it is determined whether or not the previous transmission is retransmission. If it is retransmission, the process proceeds to step S19. If not, the process proceeds to step S23.

  In step S19, it is determined that the transmission has failed, and a response frame 62 including dummy ACK data is transmitted.

  In step S20, the process ends.

  In step S21, it is determined whether or not a NACK indicating incomplete data transmission has been received. If received, the process proceeds to step S22, and if not received, the process proceeds to step S15.

  In step S22, it is determined whether or not NACK data is received for the second time. If it is the second time, the process proceeds to step S24. If not, the process proceeds to step S23.

  In step S23, the transmission data is reset.

  In step S24, it is determined that the transmission has failed, and a response frame 62 including dummy ACK data is transmitted.

  In step S25, the process ends.

[Receive processing]
FIG. 4 is a flowchart showing the flow of reception processing executed by the CPU n1 of each of the communication units 1, 2 and 3 according to the communication method of the first embodiment. Each step will be described below.

  In step S31, reception processing is started.

  In step S32, it is determined whether or not ACK data transmitted from another communication unit has been received. If received, the process proceeds to step S33, and if not received, the process proceeds to step S36.

  In step S33, it is determined whether or not the transmission source ID number S_ID of the response frame 62 including the received ACK data is one before the own unit ID number (own ID-1). If there is, the process proceeds to step S34, and if not, the process proceeds to step S41.

  In step S34, the timer count of the idling time of the communication line is activated.

  In step S35, it is determined whether or not the count time has reached T2 (50 ms). If T2 is reached, the process proceeds to step S12 in FIG. 3 and the transmission process is performed. If T2 is not reached, step S35 is performed. And wait for it.

  In step S36, it is determined whether or not data has been received. If data has been received, the process proceeds to step S37. If no data has been received, the process proceeds to step S40.

  In step S37, it is determined whether T_ID indicating the partner station of the received data is the same as the ID of the own communication unit, that is, whether the data is for the own communication unit. If the communication unit is not for the communication unit, the process proceeds to step S40.

  In step S38, a response frame 62 including ACK data indicating that normal data reception has been performed is transmitted.

  In step S39, the process ends.

  In step S40, it is determined whether the time counted for unit failure detection has reached T4. If T4 is reached, the process proceeds to step S12 in FIG. If so, the process proceeds to step S32.

  In step S41, it is determined whether or not the transmission source ID number S_ID of the response frame 62 including the received ACK data is two before the own unit ID number (own ID-2). If there is, the process proceeds to step S42, and if not, the process proceeds to step S32.

  In step S42, timer counting for failure detection is started.

[Communication control processing]
Communication processing according to the communication method of the first embodiment will be described.
For the sake of explanation, it is assumed that serial communication is constituted by the communication units 1, 2, and 3.
The communication frame data in FIG. 7 is expressed in hexadecimal, the data indicating the first flag is AAH, the data indicating the end flag is FFH, the data indicating ACK is 10H,
Data indicating NACK is set to 5AH.

In the communication system using the communication method of the first embodiment, communication is performed without a master / slave relationship as shown in FIG.
First, when data is transmitted from the communication unit 1 to the communication unit 3, the CPU 11 of the communication unit 1 sets the S_ID indicating its own unit to ID = 1 (01H) and sets the T_ID indicating the other party to ID = 3 (03H). The first flag is set (AAH), and the communication frame 61 is output to the transmission circuit 12. The transmission circuit converts the data from the CPU 11 and sends it to the communication line 5 (steps S12 → S13). The communication unit 3 as a partner station receives the data, and if the transmission destination is its own unit, sends a response frame 62 including ACK data (10H) to the communication line 5 (steps S36 → S37 → S38).

  That is, the transmission data sent to the communication line 5 is received by all units, and only the corresponding unit adopts the data and returns a response (see FIG. 7A).

When the communication unit 2 receives the response frame 62 including the ACK data transmitted by the communication unit 3, the T_ID included in the response frame 62 indicates ID = 1, and thus becomes the ID-1 of its own unit. This is detected in the process, and a timer is started in the process of step S34.
If T2 = 50 ms elapses, the communication unit 2 transmits to the communication unit 1, for example, assuming that the transmission of the communication unit 1 with ID = 1 is completed.

When receiving the data, the communication unit 1 transmits a response frame 62 including ACK to the communication unit 2, and when the ACK data is received by the communication unit 2, the transmission is completed (see FIG. 7B).
In this way, each communication unit performs transmission / reception in the order of ID while receiving a response frame 62 including ACK data, as shown in FIG.
When the communication between the communication unit 1 and the communication unit 3 is completed by transmission from the communication unit 3 to the communication unit 1 based on the content, the communication unit 3 displays the end flag (FFH) shown in FIG. The included communication frame 61 is transmitted to the communication unit 1, and the communication unit 1 transmits a response frame 62 including an end flag (FFH) to the communication unit 3, thereby completing one communication.

Therefore, the communication unit 1 confirming the end of communication by the end flag performs the next communication as shown in FIG.
For example, in data transmission from the communication unit 2 to the communication unit 3, a predetermined value obtained by calculation from the data of the communication frame 61 received by the communication unit 3 in this case is the checksum of the received communication frame 61. If it is determined that normal data cannot be received, a response frame 63 including NACK data is transmitted from the communication unit 3 to the communication unit 2 (see FIG. 7E).

When the communication unit 2 that is the transmission source receives the NACK data, the communication unit 2 retransmits the same transmission data by the process of step S23 as shown in FIG.
When the retransmission is established, the response frame 62 including the ACK data is transmitted from the communication unit 3 to the communication unit 2 (see FIG. 7F).

Furthermore, processing at the time of retransmission of data transmission will be described with reference to the time chart of FIG.
For the sake of explanation, it is assumed in FIG. 6 that a communication network is configured by the communication units 1, 2, 3, and 4.
When normal communication is performed, transmission of the communication frame 61 from the communication unit 1 → transmission of the response frame 62 to the communication unit 1 → transmission of the communication frame 61 from the communication unit 2 → response frame to the communication unit 2 Transmission and communication of 62 continue (see FIG. 6A).

<1> When ACK data is not responded When data is transmitted from the communication unit 1 to another communication unit and no response frame is transmitted from the communication unit, the communication unit 1 counts a timer by the process of step S15 at the time of transmission. Therefore, it is determined that data communication has not been established due to the elapse of time T1, and retransmission is performed by the process of step S23 (see FIG. 6B).

<2> When NACK Data is Responded The communication unit that is the transmission destination from the communication unit 1 collates the calculation result of the received communication frame data with the checksum SUM. If the collation does not match, the data has not been received correctly, and therefore a response frame 63 including NACK data is transmitted from the communication unit at the transmission destination to the communication unit 1, and retransmission is performed (FIG. 6). (See (c)).

<3> If there is no ACK data response even if the retransmission is performed twice. If there is no ACK data response from the destination, the retransmission is performed after the time T1. If the ACK data is not responded in time, or if the NACK data is responded to the second transmission, in order to pass the communication right to another communication unit by the process of step S19 or step S24. A response frame 62 including dummy ACK data is transmitted (see FIG. 6D).
The communication unit of the next ID that has received the response frame 62 including the dummy ACK data determines that the communication of the communication unit of the previous ID has been completed and performs the next communication.

<4> When communication unit 3 has failed If communication unit 3 has failed, response frame 62 including ACK data from communication unit 3 is received by another unit after communication of communication unit 2 is completed. Not. When the time T4 elapses in this state, the communication right is transferred to the communication unit 4 as a result of detecting the failure of the communication unit 3 by the process of step S40.

Next, the effect will be described.
In the communication method of the first embodiment, the effects listed below can be obtained.
(1) In a communication method in an in-vehicle network configured by connecting a plurality of in-vehicle communication units in a bus type with serial communication lines, non-overlapping ID data is assigned to each communication unit, and each communication unit transmits data in the order of ID data. The transmission source communication unit provides the communication frame 61 with a first / end flag F / E_F indicating the start and end of data transmission and S_ID indicating the transmission source ID data. When the first / end flag F / E_F indicating the start and end of data transmission is received, the transmission destination communication unit indicates that the reception corresponding to the flag data is established, and T_ID indicating the source ID data The response frames 62 and 63 including the first and second data are transmitted to the transmission source communication unit, and the first / Since the next communication unit in the order of ID data detects that the response frames 62 and 63 corresponding to the received flag F / E_F have been transmitted and performs transmission / reception one after another, the communication load of the CPU of each communication unit can be equalized. The communication of each communication unit can be performed efficiently.

  (2) If the transmission source communication unit does not receive the response frames 62 and 63 from the transmission destination communication unit within the time T1 after transmission, it is determined as a transmission error and communication by another communication unit is started. Therefore, since the source communication unit transmits dummy response data corresponding to the first / end flag F / E_F indicating the end of data transmission, the communication right of the communication unit that has failed or disconnected from the communication line is It can be quickly passed to the next communication unit to maintain efficient communication.

  (3) The destination communication unit corresponds to the first / end flag F / E_F indicating the end of data transmission from the transmission source when data is incompletely received, and indicates incomplete reception When the response data is transmitted and the communication unit of the transmission destination receives the response data indicating incompletion of reception from the transmission destination, retransmission is performed, and thus the reliability of data communication can be improved.

  As described above, the communication method of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to these embodiments, and the gist of the invention according to each claim of the claims is described. Unless it deviates, design changes and additions are allowed.

In the case of an in-vehicle device, the communication unit shown in the embodiment has a partial configuration of each device.
It is desirable to assign ID numbers in the priority order of devices.

It is a figure which shows the structure of the communication system using the communication method of Example 1. FIG. It is explanatory drawing which shows the format of the communication data used with the communication method of Example 1. FIG. It is a flowchart which shows the flow of the transmission process performed with the communication unit of the communication system using the communication method of Example 1. FIG. 3 is a flowchart illustrating a flow of reception processing executed by a communication unit of a communication system using the communication method of Embodiment 1. 6 is an explanatory diagram illustrating a communication procedure of a communication method according to the first embodiment. 3 is a timing chart illustrating communication timings of the communication method according to the first exemplary embodiment. It is explanatory drawing which shows the communication state of the communication method of Example 1. FIG. It is a figure which shows the structure of the communication system using a master / slave system. It is explanatory drawing which shows the format of the communication data used with a master / slave system. It is a flowchart which shows the flow of the transmission process performed with the communication unit of the communication system using a master / slave system. It is a flowchart which shows the flow of the reception process performed with the communication unit of the communication system using a master / slave system. It is explanatory drawing which shows the communication procedure of a master / slave system. It is a timing chart which shows the communication timing of a master / slave system. It is explanatory drawing which shows the communication state of a master / slave system.

Explanation of symbols

1 Communication unit 2 Communication unit 3 Communication unit 11 CPU
21 CPU
31 CPU
DESCRIPTION OF SYMBOLS 12 Transmission circuit 22 Transmission circuit 32 Transmission circuit 13 Reception circuit 23 Reception circuit 33 Reception circuit 5 Communication line 6 Communication format 61 Communication frame 62 Response frame (ACK)
63 Response frame (NACK)
LENGTH data length
S_ID ID number of your station
T_ID ID number of the partner station
F / E_F First / End flag
DATAn data
SUM Checksum
ACK Data indicating the completion of normal data transmission
NACK Data indicating incomplete data transmission M Master unit S1 to S4 Slave unit Fm (Master unit) communication frame Fs (Slave unit) communication frame

Claims (3)

In a communication method in an in-vehicle network configured by connecting a plurality of vehicle-mounted communication units in a bus shape with a serial communication line,
Assign unique ID data to each communication unit,
Each communication unit gets an opportunity of data transmission in the order of the ID data,
The transmission source communication unit provides flag data indicating the start and end of data transmission and the transmission source ID data in the transmission data and transmits it to the transmission destination communication unit.
When receiving the flag data indicating the start and end of data transmission, the transmission destination communication unit indicates that the reception corresponding to the flag data is established, and transmits response data including the transmission source ID data to the transmission source communication unit.
The next communication unit in the ID data order detects that the response data corresponding to the flag data indicating the end of data transmission is transmitted from the destination communication unit, and performs transmission and reception one after another.
A communication method characterized by the above. The communication method according to claim 1,
The source communication unit is
If the response data from the destination communication unit is not received within a predetermined time after transmission, it is determined as a transmission error,
In order to start communication by another communication unit, the transmission source communication unit transmits temporary response data corresponding to flag data indicating the end of data transmission.
A communication method characterized by the above. The communication method according to claim 2,
The destination communication unit is
When the data is incompletely received, it responds to flag data indicating the end of data transmission from the transmission source, and transmits response data indicating incomplete reception,
The destination communication unit is
When response data indicating incomplete reception from the destination is received, retransmission is performed.
A communication method characterized by the above.

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