WO2010004768A1 - 通信装置、通信システム及び通信方法 - Google Patents
通信装置、通信システム及び通信方法 Download PDFInfo
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- WO2010004768A1 WO2010004768A1 PCT/JP2009/003253 JP2009003253W WO2010004768A1 WO 2010004768 A1 WO2010004768 A1 WO 2010004768A1 JP 2009003253 W JP2009003253 W JP 2009003253W WO 2010004768 A1 WO2010004768 A1 WO 2010004768A1
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- 230000006854 communication Effects 0.000 title claims abstract description 216
- 238000004891 communication Methods 0.000 title claims abstract description 214
- 238000000034 method Methods 0.000 title claims abstract description 53
- 230000005540 biological transmission Effects 0.000 claims abstract description 187
- 238000012546 transfer Methods 0.000 claims description 18
- 230000005764 inhibitory process Effects 0.000 claims 1
- 238000012545 processing Methods 0.000 description 33
- 238000005259 measurement Methods 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 230000001360 synchronised effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 239000000284 extract Substances 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/407—Bus networks with decentralised control
- H04L12/413—Bus networks with decentralised control with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
- H04L12/4135—Bus networks with decentralised control with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD] using bit-wise arbitration
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/44—Star or tree networks
Definitions
- the present invention relates to a communication system that transmits and receives data between a plurality of communication devices.
- the present invention relates to a communication device that can specify a generation point of received data with a simple configuration, a communication system including the communication device, and a communication method.
- each data When data is processed by exchanging data whose contents change from moment to moment between a plurality of communication devices, each data has a valid period.
- the control performed by the ECU in the field of the in-vehicle LAN is related to safety, there is a possibility that a problem may occur if extremely old data is used.
- Patent Document 1 discloses a technique for minimizing data arriving after the arrival deadline time by a configuration in which each ECU controls transmission and reception of data in the order according to the priority based on the arrival deadline time of data.
- the arrival deadline time is an absolute time
- each ECU transmits data with a shorter time until the arrival deadline time using a time measurement unit that measures a synchronized reference time. I have to do it.
- each ECU is configured to measure a synchronized reference time, so that each ECU receives data generation times measured by other communication devices, thereby generating data. Can be accurately recognized.
- each communication device performs a process of matching the time measured by its own clocking means with a reference time transmitted from one communication device, or each communication device has GPS (Global Positioning System)
- GPS Global Positioning System
- the present invention has been made in view of such circumstances, and the generation time point of data received from another communication device can be determined with a simple configuration without synchronizing the time measured by the time measuring means included in each communication device. It is an object of the present invention to provide a communication device that can be specified accurately, a communication system including the communication device, and a communication method.
- a communication apparatus comprising: a timing unit; a communication unit that transmits and receives data; and a transmission availability determination unit that determines whether data can be transmitted by the communication unit.
- the communication means receives the data with the time difference information added thereto, the means for specifying the reception start time based on the time measured by the time measuring means, and the data generation time based on the time difference information and the reception start time.
- a specifying means for specifying when the communication means receives the data with the time difference information added thereto, the means for specifying the reception start time based on the time measured by the time measuring means, and the data generation time based on the time difference information and the reception start time.
- a specifying means for specifying for specifying.
- the time measuring means acquires a data transmission start time, the acquired transmission start time, and the generation of the data Means for obtaining a time difference between time points, and time difference information indicating the obtained time difference is added to the data that has started transmission.
- a communication device includes a determination unit that determines a transmission start time point for transmitting data, a unit that determines a time difference between the determined transmission start time point and the generation time point, and time difference information indicating the calculated time difference.
- Means for adding to the data means for determining whether or not the transmission start time determined by the determination means has been reached, and when determining that the transmission start time has been reached, Means for attempting to transmit the data and the time difference information added to the data by the communication means, and when the transmission availability determination means determines that the transmission is not possible, It is characterized by re-determining, re-determining the time difference and trying transmission again.
- the communication device When the communication device according to the fourth aspect of the invention receives the data to which the time difference information is added by the communication device, the communication device further transfers the data to another communication device by the communication device, and the data specified by the specifying device. Means for obtaining a time difference between the generation time of the data and the data transfer start time, and means for using the time difference information indicating the obtained time difference as time difference information added to the data to be transferred.
- a communication system is a communication system including a plurality of communication devices each including a time measuring unit, a communication unit that transmits and receives data, and a transmission availability determination unit that determines whether data can be transmitted by the communication unit.
- Each communication device has a time difference between a generation time point at which data is generated and a time difference between a transmission start time point at which transmission is determined by the transmission permission determination unit and transmission of the data is started.
- Means for adding time difference information indicating to the data means for specifying a reception start time based on the time measured by the time measuring means, when the data to which the time difference information is added is received by the communication means, the time difference information and the reception And a specifying means for specifying a data generation time based on the start time.
- a communication method in which a communication device comprising a time measuring means and a communication means for transmitting and receiving data determines whether or not data can be transmitted by the communication means,
- the communication device determines that transmission is possible
- the communication device starts data transmission, acquires the transmission start time of the data by the timing unit, and the acquired transmission start time and the data are generated.
- a time difference between the generation points is obtained, and time difference information indicating the obtained time difference is added to the data that has been transmitted and transmitted.
- a communication method in which a communication device comprising a time measuring means and a communication means for transmitting / receiving data determines whether or not data can be transmitted by the communication means,
- the communication apparatus determines a transmission start time point for transmitting data, obtains a time difference between the determined transmission start time point and a generation time point when the data is generated, and sets time difference information indicating the obtained time difference as the data And determines whether or not the determined transmission start time has been reached, and if it is determined that the transmission start time has been reached, the communication means transmits the data and the time difference information added to the data. If it is determined that the transmission of the data is impossible, the transmission start point for starting the next transmission is re-determined, the time difference is re-determined, and the transmission is retried.
- time difference information indicating a time difference between a generation time when data is generated and a transmission start time at which the transmission of the data is actually possible and transmission is started is added to the data. Is done. If the time difference from the start of transmission to the start of reception can be ignored, the time point past the time difference indicated by the time difference information from the reception start time point is the time when the data is generated.
- the transmission start time when data transmission is determined to be possible and data transmission is started is obtained, and the time difference from the data generation time is obtained.
- a time difference is obtained based on information on the accurate transmission start time at which transmission is actually started, and is added to the data being transmitted and transmitted.
- the data transmission start time is determined in advance, the time difference between the determined transmission start time and the data generation time is obtained in advance, and the time difference information is added to the data.
- the time difference represented by the time difference information already added to the data being transmitted is accurate. If it is determined that transmission is not possible and transmission is not started, the transmission start time is re-determined in accordance with the next transmission opportunity, time difference information is obtained again, and transmission is attempted. Thereby, even when it is difficult to add time difference information to the data being transmitted, it is possible to add time difference information that can specify an accurate generation time point with a simple configuration.
- the communication device that has received the data determines the accurate data generation time based on the time measured by its own time measuring means based on the time difference information received together. It becomes possible to specify.
- the present invention it is possible to accurately specify the generation time point of data to be transmitted / received with a simple configuration without synchronizing the time measured by the time measuring means provided in each communication device.
- FIG. 1 is a configuration diagram showing a configuration of an in-vehicle communication system in a first embodiment.
- 4 is a flowchart illustrating an example of a communication processing procedure in which the control unit of the ECU according to the first embodiment generates data and transmits the data together with time difference information.
- 6 is a flowchart illustrating an example of processing in which a control unit of an ECU or a control unit of a relay device in Embodiment 1 receives data and specifies a generation time point.
- 6 is a flowchart illustrating an example of a communication processing procedure when the control unit of the relay device in Embodiment 1 transfers data.
- FIG. 6 is a flowchart illustrating an example of a communication processing procedure in which a control unit of an ECU according to Embodiment 2 generates data and transmits the data together with time difference information.
- 10 is a flowchart illustrating an example of a communication processing procedure when the control unit of the relay apparatus according to the second embodiment transfers data.
- FIG. 1 is a configuration diagram showing the configuration of the in-vehicle communication system in the first embodiment.
- the in-vehicle communication system according to the first embodiment includes ECUs 1, 1,... That are communication devices that transmit and receive data, relay devices 2a, 2b,. ,... And relay devices 2a, 2b,..., And communication lines 3a, 3b,.
- the ECUs 1, 1,... Are connected to different communication lines 3a, 3b,.
- the relay device 2a is connected to both the communication lines 3a and 3b, and relays data transmission / reception between the ECUs 1, 1,... Connected to the communication lines 3a and 3b, respectively.
- the relay device 2b is connected to both the communication lines 3b and 3c, and relays data transmission and reception between the ECUs 1, 1,... Connected to the communication lines 3b and 3c, respectively.
- Each of the ECUs 1, 1,... Communicates via a control unit 10 that controls the operation of each component, a storage unit 11 that stores data necessary for control, a time measuring unit 12, and communication lines 3a, 3b,.
- the communication control part 13 which controls this is provided.
- the control unit 10 of the ECU 1 receives power supplied from a power supply device such as a vehicle battery and an alternator (not shown) to control the operation of each component.
- a power supply device such as a vehicle battery and an alternator (not shown) to control the operation of each component.
- the storage unit 11 uses a volatile memory, and the control unit 10 is relayed by various information generated in the course of processing, measured values represented by signals input from sensors or relay devices 2a, 2b,.
- the stored data is temporarily stored in the storage unit 11.
- Time measuring unit 12 measures the passage of time by counting at a predetermined frequency.
- the time measuring unit 12 measures an elapsed time from a predetermined reference time.
- the reference time point in the time measuring unit 12 may be a time point at which power is supplied, or an arbitrary time (for example, UTC; Coordinated Universal Time).
- the control unit 10 acquires time information at an arbitrary timing from the time measuring unit 12. Note that the time indicated by the time information acquired by the control unit 10 from the time measuring unit 12 is a local time in each of the ECUs 1, 1,... And does not need to be synchronized.
- the communication control unit 13 has a network controller function and realizes communication via any one of the communication lines 3a, 3b,.
- the ECUs 1, 1,... And the relay devices 2a, 2b,... Transmit and receive data in accordance with a CAN (Controller-Area-Network) protocol. Therefore, the communication control unit 12 transmits and receives data via the communication lines 3a and 3b based on the CAN protocol.
- the control unit 10 of the ECU 1 connected to the communication line 3a monitors the communication status on the communication line 3a by the communication control unit 12, determines whether or not it can transmit data, and can transmit it. Send data in case.
- one ECU 1 connected to the communication line 3a communicates when the other ECUs 1, 1,...
- any one of the ECUs 1, 1,... And the relay device 2a connected to the communication line 3a tries to start data transmission at the same time, any one can preferentially transmit data by arbitration. It is. Specifically, an arbitration field for arbitration is included in the header added to the head of data transmitted / received according to the CAN protocol, and arbitration is performed on the communication line 3a by a bit string in the arbitration field. Only one ECU 1 or relay device 2a that has won the arbitration can continue transmission. Further, when any of the ECUs 1, 1,... Connected to the communication line 3a and the relay device 2a transmit data via the communication line 3a, the other ECUs 1, 1 connected to the communication line 3a. ,... Or the relay apparatus 2a simultaneously receives data.
- the ECUs 1, 1,... Configured as described above are devices that can transmit data including numerical information of various physical quantities such as measured values, calculated values, and control values, or can be controlled by a microcomputer such as an engine and a brake.
- a microcomputer such as an engine and a brake.
- one ECU 1 connected to the communication line 3a functions as an ABS (Antilock Brake System) and is connected to a sensor (not shown) that detects the rotational speed (wheel speed) of the wheel.
- the ECU 1 controls the brake based on the wheel speed detected via the sensor during braking of the vehicle, and also uses the measured value of the wheel speed as data to communicate with the other ECUs 1, 1,... And the relay device 2a via the communication line 3a. Send to.
- the ECUs 1, 1,... Transmit data including numerical information of various physical quantities such as measured values, calculated values, control values, etc., when data is generated, for example, when wheel speed measured values are detected via sensors. Information for identification is added after the data and transmitted. Specifically, the control unit 10 of the ECUs 1, 1,... Adds time difference information representing a time difference from the generation time point to the data transmission start time point. Further, when it is necessary for the ECUs 1, 1,... That have received the data to refer to the generation time of the received data, the time difference information added to the data is used to indicate the time point before the time difference indicated by the time difference information from the reception start time point. It is specified as the generation time.
- the relay device 2a includes a control unit 20 that controls the operation of each component, a storage unit 21 that stores various types of information, a timing unit 22, and a communication unit 23 connected to the communication lines 3a and 3b.
- the internal configuration of the relay devices 2b, 2c,... Is the same as the internal configuration of the relay device 2a, and detailed description thereof is omitted.
- the control unit 20 uses an MPU (Micro Processing Unit) and is configured to receive power from a power supply device (not shown) such as an alternator of a vehicle or a battery to control the operation of each component.
- MPU Micro Processing Unit
- the storage unit 21 temporarily stores data received from the ECUs 1, 1,... Using a volatile memory. Various kinds of information generated and used in the process of the control unit 20 are stored in the storage unit 21.
- Time measuring unit 22 measures the passage of time by counting at a predetermined frequency.
- the timer unit 22 measures an elapsed time from a predetermined reference time.
- the reference time point may be a time point at which power is supplied, or may be an arbitrary time (for example, UTC), like the time measuring unit 12 in the ECUs 1, 1,.
- the control unit 20 acquires time information at an arbitrary timing from the time measuring unit 22.
- the time represented by the time information acquired from the timer unit 22 is the local time in the relay devices 2a, 2b,..., And the timer units 22 and timer units of the other relay devices 2a, 2b,. 12 need not be synchronized.
- the communication unit 23 realizes data transmission / reception with the ECUs 1, 1,... Connected via the communication lines 3a, 3b,. That is, data is transmitted and received according to the CAN protocol.
- the communication unit 23 has a plurality of ports and can connect to different communication lines 3a, 3b,... To transmit and receive data.
- the control unit 20 of the relay device 2a connected to the communication lines 3a and 3b monitors the communication status on the communication line 3a by the communication unit 23, determines whether or not it can transmit data, and can transmit the data. If so, data is transmitted via the communication line 3a.
- the relay device 2a monitors the communication status on the communication line 3b by the communication unit 23, determines whether or not it can transmit data, and if it can transmit data, the data is transmitted via the communication line 3b. Send. Note that the communication unit 23 can simultaneously perform transmission and reception through different ports.
- the control unit 20 of the relay apparatuses 2a, 2b,... Configured as described above transfers data received from the ECUs 1, 1,... Via the communication unit 23 from other ports to the other ECUs 1, 1,.
- time difference information for specifying the generation time point of the data that is added to the data and transmitted is also transferred.
- the control unit 20 transfers the time difference information after changing it. Specifically, the control unit 20 adds the time difference from the reception start time to the transfer start time to the time difference indicated by the time difference information added to the received data to obtain the time difference from the generation time to the transfer start time, The time difference information added to the data to be transferred is changed to time difference information indicating the obtained time difference and then transferred.
- FIG. 2 is a flowchart illustrating an example of a communication processing procedure in which the control unit 10 of the ECUs 1, 1,... In Embodiment 1 generates data and transmits the data together with time difference information.
- the flowchart shown below shows the process by the control part 10 of one ECU1 connected to the communication line 3a. The processing by the control unit 10 of the other ECUs 1, 1,.
- the control unit 10 detects a measurement value via a sensor, obtains a calculated value triggered by receiving other data, or obtains a control value to be controlled. Data including numerical information on the physical quantity is generated (step S11). At this time, the control unit 10 acquires the time point when the data is generated, that is, the data generation time point (Tc (0) ) by the time measuring unit 12 (step S12).
- a number is shown on the shoulder of the algebra representing each time point information, such as the data generation time point (Tc (0) ) in step S12 described above.
- the number is an arbitrary natural number (k) for explaining which device is the time information represented by the local time, and corresponds to the number of data relays. For example, “0 (zero)” at the data generation time point (Tc (0) ) in step S12 indicates that the time information is represented by the local time in the device in which the data is generated (the data starting device). Show. Note that the number shown on the shoulder does not have to be included in the transmitted / received time difference information.
- the control unit 10 attempts to transmit the data generated in step S11 by the communication control unit 13, and determines whether or not the transmission start is successful (step S13).
- the control unit 10 has failed to start transmission because another ECU 1, 1,... Connected to the communication line 3a or the relay device 2a is communicating, or has started transmission of data but lost to arbitration. (S13: NO), the process returns to step S13 and waits until transmission can be started. In this case, the control unit 10 receives the data transmitted from the other ECUs 1, 1,... Or the relay device 2a by the communication control unit 13.
- the transmission start time (Ts (0) ) is acquired by the time measuring unit 12 (step S14). Strictly speaking, the transmission start time (Ts (0) ) indicates the transmission time at the end of the arbitration field.
- control unit 10 obtains a time difference based on information on the accurate transmission start time (Ts (0) ) at which transmission is actually started, and is added to the data being transmitted and transmitted.
- the communication control unit 13 when transmitting data, the communication control unit 13 adds header information including an arbitration field to the head of the data and adds trailer information indicating the end of data transmission to the end of the data.
- the header information includes the length from the header information to the end of the trailer information. Therefore, the time difference information is defined so as to be represented by a field having a predetermined length following the specific numerical information of the data. Arbitrary numerical information is entered in advance in the field representing the time difference information.
- the communication control unit 13 is configured to be able to rewrite the field representing the time difference information after the data transmission is started.
- Transmission start time controller 10 upon successful start of the transmission by the communication control unit 13 (Ts (0)) the time difference to get the (Td (0)) from the calculated, the communication control unit 13 for two hours difference information To rewrite. This makes it possible to add time difference information during transmission.
- FIG. 3 is a flowchart showing an example of a process in which the control unit 10 of the ECUs 1, 1,... Or the control unit 20 of the relay devices 2a, 2b,.
- the flowchart shown below shows processing by one ECU 10 connected to the communication line 3b.
- the control unit 10 determines whether or not reception of data is started by the communication control unit 13 (in the case of processing by the control unit 20 of the relay devices 2a and 2b, the communication unit 23) (step S21). When it is determined that the reception of data has not started (S21: NO), the control unit 10 returns the process to step S21.
- the control unit 10 of the ECU 1 connected to the communication line 3b can specify the generation time point of the data generated and transmitted by the ECU 1 connected to the communication line 3a, for example. Since the time difference information is a time difference from when data is actually generated to when transmission is actually started, the time point after the time difference from the reception start time is an accurate data generation time. Note that the numerical information k in the description of the flowchart of FIG. 3 corresponds to the number of relays from the device that generated the data.
- FIG. 4 is a flowchart illustrating an example of a communication processing procedure when the control unit 20 of the relay apparatuses 2a, 2b,... In the first embodiment transfers data.
- the control unit 20 of one relay device 2a connected to the communication lines 3a and 3b receives data received from the ECU 1 connected to the communication line 3a and is connected to the communication line 3b.
- the processing when transferring to each device is shown.
- the processing when transmitting data transmitted from any of the devices connected to the communication line 3b to the ECUs 1, 1,... Connected to the communication line 3a is the same.
- the control unit 20 determines whether or not reception of data is started by a port connected to the communication line 3a of the communication unit 23 (step S31). When it is determined that the data reception has not started (S31: NO), the control unit 20 returns the process to step S31, monitors the connected communication line 3a, and waits until the data reception starts. .
- the control unit 20 acquires the reception start time (Tm (k) ) by the time measuring unit 22 (step S32). The control unit 20 determines whether or not the reception of data has been completed (step S33). If it is determined that the data has not been completed (S33: NO), the process returns to step S33.
- control unit 20 When the control unit 20 detects the trailer information by the communication unit 23 and determines that the reception of the data has been completed (S33: YES), the control unit 20 indicates the time difference (Td (k-1) ) added to the received data. Time difference information is extracted (step S34).
- the control unit 20 communicates data transmission.
- the unit 23 tries to determine whether or not transmission has been successfully started (step S35).
- the control unit 20 fails to start transmission because another ECU 1, 1,... Connected to the communication line 3b or the relay device 2b is communicating, or has started transmission of data but lost to arbitration. If it is determined (S35: NO), the process returns to step S35 and waits until transmission can be started.
- the control unit 20 has succeeded in starting the transmission because the other ECUs 1, 1,... Connected to the communication line 3b and the relay device 2b are not communicating and have started transmission of data and won arbitration. If it is determined (S35: YES), the transmission start time (Ts (k) ) is acquired by the time measuring unit 22 (step S36).
- the control unit 20 adds a time difference (Td (k-1) ) indicated by the received time difference information to a time difference between the transmission start time (Ts (k) ) and the reception start time (Tm (k) ).
- Td (k-1) Td (k-1) + (Ts (k) -Tm (k) )) is calculated (step S37), and the time difference information indicating the time difference (Td (k) ) is added to the data being transmitted. 23 (step S38), the transmission is completed, and the process is terminated.
- the communication unit 23 performs a communication process according to the CAN protocol, and the process of adding time information in step S38 is performed as follows in the same manner as the communication control unit 13.
- the time difference information is represented by a field having a predetermined length following the specific numerical information of the data, and the control unit 20 puts arbitrary numerical information in advance in the field representing the time difference information.
- the communication unit 23 is configured to be able to rewrite the field representing the time difference information after starting transmission.
- the control unit 20 calculates the acquired by the time difference the transmission start time upon successful start of the transmission (Ts (k)) by the communication unit 23 (Td (k)), rewrite the communication unit 23 two hours difference information To instruct.
- FIG. 5 shows that the generation time point of data transmitted / received by the ECUs 1, 1,... And the relay devices 2a, 2b,. It is explanatory drawing which shows the process performed. FIG. 5 shows that time has passed downward. Note that the explanatory diagram of FIG. 5 shows an example in which data is generated by the ECU 1 connected to the communication line 3a and is transferred by the relay devices 2a, 2b,.
- the generation time point acquired by the ECU 1 is Tc (0) .
- the relay device 2a transfers the data received from the ECU 1 to the ECUs 1, 1,... Connected to the communication line 3b and the relay device 2b.
- the control unit 20 of the relay device 2a acquires the transmission start time Ts (1) successful start of the transmission by the communication unit 23, a transmission start time Ts (1 ) And the generation time Tc (1) of the data, that is, the time difference Td (0) added to the received data, the reception start time Tm (1) and the transmission start time Ts (1) in itself.
- the time difference information indicating the time difference Td (1) obtained by adding the time differences between the two is added and transmitted.
- the ECUs 1, 1,... Connected to the communication line 3b When the ECUs 1, 1,... Connected to the communication line 3b receive the data transferred by the relay device 2a, they start receiving the time difference Td (1) indicated by the added time difference information and the data itself. Based on the time Tm (2) , the data generation time Tc (2) in the local time of the ECU 1 itself can be specified.
- the ECU 1 that has received the data relayed (transferred) k times also includes the time difference Td (k ⁇ 1) indicated by the added time difference information and the time Tm (k) at which the data reception starts.
- Td (k ⁇ 1) indicated by the added time difference information
- Tm (k) the time difference indicated by the time difference information added to the received data
- Tc (k) the time difference between the data generation time and the transmission (reception) start time represented by a predetermined frequency. is there. Therefore, even many times relayed data, the time difference Td than the reception start time point Tm (k) (k-1 ) minute predated time Tc (k) is the data generation time.
- the timekeeping unit 12 of the ECUs 1, 1,... And the timekeeping unit 22 of the relay devices 2a, 2b,... are expressed in local time in each device even though they are not synchronized with reference to a predetermined absolute time. It is possible to specify the generation time. That is, as shown in FIG. 5, even if Tc (0) , Tc (1), and Tc (k) are represented by different numerical values, the generation times Tc (0) , Tc ( 1) and Tc (k) correspond to simultaneous points as shown in FIG.
- the control unit 10 of the ECUs 1, 1,... And the control unit 20 of the relay devices 2a, 2b,... Acquire the transmission start time and add it to the data being transmitted when the transmission is successfully started. It was set as the structure to do.
- a transmission start time is determined in advance, and transmission is attempted after obtaining time difference information to be added to data.
- the configuration of the in-vehicle communication system in the second embodiment is the same as that in the first embodiment except for the details of the processing by the control unit 10 of the ECUs 1, 1,... And the details of the processing by the control unit 20 of the relay devices 2a, 2b,. It is the same.
- the same reference numerals are assigned to components common to the first embodiment, and detailed description thereof is omitted, and details of processing by the control unit 10 of the ECUs 1, 1,..., Which are different points, and relay devices 2a, 2b, Details of the processing by the control unit 20 will be described with reference to a flowchart.
- FIG. 6 is a flowchart illustrating an example of a communication processing procedure in which the control unit 10 of the ECUs 1, 1,... In Embodiment 2 generates data and transmits the data together with time difference information.
- the flowchart shown below shows the process by the control part 10 of one ECU1 connected to the communication line 3a. The processing by the control unit 10 of the other ECUs 1, 1,.
- the same processing steps as those shown in the flowchart of FIG. 2 in the first embodiment are given the same step numbers, and detailed description thereof is omitted.
- the control unit 10 adds time difference information indicating the calculated time difference (Td (0) ) to the generated data (step S43), and compared with the time measurement by the time measurement unit 12, the transmission start time (Ts determined in step S41). It is determined whether or not (0) ) has been reached (step S44). If the control unit 10 determines that the transmission start time (Ts (0) ) has not been reached (S44: NO), the process returns to step S44.
- control unit 10 determines that the transmission start time (Ts (0) ) has been reached (S44: YES)
- the communication control unit 13 attempts to transmit the data generated in S11, and whether or not the transmission start is successful. Is determined (step S45).
- the control unit 10 has failed to start transmission because another ECU 1, 1,... Connected to the communication line 3a or the relay device 2a is communicating, or has started transmission of data but lost to arbitration. (S45: NO), the process returns to step S41 to re-determine the transmission start time (Ts (0) ) for the next transmission attempt.
- control unit 10 determines that the other ECUs 1, 1,... And the relay device 2a are not communicating, start transmission of data, and have succeeded in arbitration, thereby successfully starting transmission (S45: YES). , The transmission is continued to complete the transmission, and the process is terminated.
- the transmission start time added to the data is a predetermined time, but when the transmission is successfully started, the actual transmission start time is reached.
- specification of the generation time by the control unit 10 of the ECUs 1, 1,... That receives the data or the control unit 20 of the relay apparatuses 2, 2,... is shown in the flowchart of FIG. This process is performed. Therefore, even when the data generation time point is specified based on the time difference information indicating the time difference (Td (0) ) in the processing procedure shown in the flowchart of FIG. 6, it is possible to correctly specify the data generation time point. is there.
- FIG. 7 is a flowchart illustrating an example of a communication processing procedure when the control unit 20 of the relay apparatuses 2a, 2b,... In the second embodiment transfers data.
- the control unit 20 of one relay device 2a connected to the communication lines 3a and 3b receives data received from the ECU 1 connected to the communication line 3a and is connected to the communication line 3b.
- the processing when transferring to each device is shown.
- the processing when transmitting data transmitted from any of the devices connected to the communication line 3b to the ECUs 1, 1,... Connected to the communication line 3a is the same.
- the control unit 20 After extracting the time difference information indicating the time difference (Td (k-1) ) added from the received data (S34), the control unit 20 uses the communication line 3b via a port where the received data is different from the received port. When the data is to be transferred to the ECUs 1, 1,... Connected to the relay device 3b, the following processing is performed.
- the control unit 20 adds time difference information indicating the calculated time difference (Td (k) ) to the generated data (step S53), and compared with the time measurement by the time measurement unit 12, the transmission start time (Ts determined in step S51). (k) ) It is determined whether or not (step S54). When the control unit 20 determines that the transmission start time (Ts (k) ) has not been reached (S54: NO), the control unit 20 returns the process to step S54.
- the control unit 20 When it is determined that the transmission start time (Ts (k) ) has been reached (S54: YES), the control unit 20 attempts to transmit data by the communication unit 23, and determines whether the transmission has been successfully started (step S54). S55). The control unit 20 fails to start transmission because another ECU 1, 1,... Connected to the communication line 3b or the relay device 2b is communicating, or has started transmission of data but lost to arbitration. (S55: NO), the process returns to step S51 to re-determine the transmission start time (Ts (k) ) for the next transmission attempt.
- control unit 20 determines that the other ECUs 1, 1,... And the relay device 2b are not communicating, or have started transmission of data and have succeeded in arbitration, and thus have successfully started transmission (S55: YES) ).
- the transmission is continued to complete the transmission, and the process is terminated.
- the transmission start time point added to the data is a predetermined time point, but when the transmission (transfer) is successfully started, the actual transmission start time point is reached. Therefore, even when the data generation time point is specified based on the time difference information indicating the time difference (Td (k) ) calculated by the processing procedure shown in the flowchart of FIG. It is possible to specify.
- data is generated including time difference information in advance and transmission or transfer is attempted.
- the communication control unit 13 and the communication unit 23 do not have to perform a process of rewriting the field representing the data time difference information during transmission.
- the time difference information indicating the time difference obtained from the time information acquired from the time measuring unit 12 of the ECUs 1, 1,... Or the time measuring unit 22 of the relay devices 2a, 2b,. did.
- the time difference information transmitted and received together with the data may be defined so as to indicate a time difference expressed in nanosecond units, for example.
- the timings in the timing units 12 of the ECUs 1, 1,... And the timing units 22 of the relay apparatuses 2a, 2b that is, even when the time measuring unit 12 in the ECU 1 connected to the communication line 3a measures time at 600 MHz and the time measuring unit 22 in the relay device 2a measures time at 3 GHz, the time difference information is transmitted and received in nanosecond units, and is controlled.
- the unit 10 or the control unit 20 can be converted into the same unit as the time information that can be acquired from the time measuring units 12 and 22.
- the communication lines 3a, 3b,... In the first and second embodiments are configured to be communication lines conforming to the CAN protocol.
- the present invention does not limit communication via the communication lines 3a, 3b,... According to CAN.
- a configuration capable of transmitting and receiving data based on a protocol such as LIN (Local Interconnect Network) or FlexRay (registered trademark) may be used.
- LIN Local Interconnect Network
- FlexRay registered trademark
- the ECUs 1, 1,... And the relay devices 2a, 2b,... are connected to the communication lines 3a, 3b,.
- a plurality of devices cannot transmit data at the same time, and when one device starts transmitting data, the other devices communicate with the communication lines 3a, 3b. ,... Were monitored simultaneously, and the time difference between the transmission start time and the reception start time could be ignored.
- the present invention is not limited to this, and a configuration in which the time difference between the transmission start time and the reception start time is not zero may be employed. This is not a problem when there is little influence on the accuracy required for the generation time point of data to be specified.
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Abstract
Description
10 制御部
12 計時部
13 通信制御部
2a,2b,… 中継装置
20 制御部
22 計時部
23 通信部
3a,3b,… 通信線
図1は、実施の形態1における車載通信システムの構成を示す構成図である。実施の形態1における車載通信システムは、データを送受信する通信装置であるECU1,1,…と、ECU1,1,…間のデータの送受信を中継する中継装置2a,2b,…と、ECU1,1,…及び中継装置2a,2b,…間を接続する通信線3a,3b,…とを含む。
実施の形態1では、ECU1,1,…の制御部10及び中継装置2a,2b,…の制御部20は、送信の開始に成功した場合に送信開始時点を取得して送信中のデータに付加する構成とした。これに対し実施の形態2では、予め送信開始時点を決定しておき、データに付加する時間差情報を求めてから送信を試みる構成とする。
Claims (7)
- 計時手段と、データの送受信を行なう通信手段と、該通信手段によるデータの送信の可否を判断する送信可否判断手段とを備える通信装置において、
データが生成された生成時点、及び、前記送信可否判断手段により可の判断がされて前記データの送信を開始する送信開始時点の間の時間差を求める手段と、
求めた時間差を示す時間差情報を前記データに付加する手段と、
時間差情報が付加されたデータを前記通信手段により受信した場合、受信開始時点を前記計時手段による計時に基づき特定する手段と、
前記時間差情報及び前記受信開始時点に基づき、データの生成時点を特定する特定手段と
を備えることを特徴とする通信装置。 - 前記送信可否判断手段が送信可であると判断した場合、前記計時手段によりデータの送信開始時点を取得する手段と、
取得した送信開始時点、及び前記データの生成時点の間の時間差を求める手段と
を備え、
求めた時間差を示す時間差情報を、送信を開始している前記データに付加するようにしてあること
を特徴とする請求項1に記載の通信装置。 - データを送信する送信開始時点を決定する決定手段と、
決定した送信開始時点、及び前記生成時点の間の時間差を求める手段と、
求めた時間差を示す時間差情報を前記データに付加する手段と、
前記決定手段が決定した送信開始時点に到達したか否かを前記計時手段による計時に基づき判断する手段と、
前記送信開始時点に到達したと判断した場合に、前記通信手段による前記データ及び該データに付加されている時間差情報の送信を試みる手段と
を備え、
前記送信可否判断手段が不可と判断した場合、前記決定手段により次に送信を開始する送信開始時点を再決定し、時間差を求め直して送信を再度試みるようにしてあること
を特徴とする請求項1に記載の通信装置。 - 時間差情報が付加されたデータを前記通信手段により受信した場合、前記データを更に他の通信装置へ前記通信手段により転送する手段と、
前記特定手段により特定したデータの生成時点、及びデータの転送開始時点の間の時間差を求める手段と、
求めた時間差を示す時間差情報を、転送するデータに付加される時間差情報とする手段と
を備えることを特徴とする請求項1乃至3のいずれかに記載の通信装置。 - 計時手段と、データの送受信を行なう通信手段と、該通信手段によるデータの送信の可否を判断する送信可否判断手段とを備える通信装置を複数含む通信システムにおいて、
各通信装置は、
データが生成された生成時点、及び、前記送信可否判断手段により可の判断がされて前記データの送信を開始する送信開始時点の間の時間差を求める手段と、
求めた時間差を示す時間差情報を前記データに付加する手段と、
時間差情報が付加されたデータを前記通信手段により受信した場合、受信開始時点を前記計時手段による計時に基づき特定する手段と、
前記時間差情報及び前記受信開始時点に基づき、データの生成時点を特定する特定手段と
を備えることを特徴とする通信システム。 - 計時手段と、データの送受信を行なう通信手段とを備える通信装置が、該通信手段によるデータの送信の可否を判断し、送信可と判断した場合に前記データを送信する方法において、
前記通信装置は、
送信可と判断した場合、データの送信を開始し、
前記計時手段により前記データの送信開始時点を取得し、
取得した送信開始時点、及び前記データが生成された生成時点の間の時間差を求め、
求めた時間差を示す時間差情報を、送信を開始している前記データに付加して送信する
ことを特徴とする通信方法。 - 計時手段と、データの送受信を行なう通信手段とを備える通信装置が、該通信手段によるデータの送信の可否を判断し、送信可と判断した場合に前記データを送信する方法において、
前記通信装置は、
データを送信する送信開始時点を決定し、
決定した送信開始時点及び前記データが生成された生成時点の時間差を求め、
求めた時間差を示す時間差情報を前記データに付加し、
決定した送信開始時点に到達したか否かを判断し、
送信開始時点に到達したと判断した場合、前記通信手段による前記データ及び該データに付加されている時点差情報の送信を試み、
前記データの送信を不可と判断した場合、次に送信を開始する送信開始時点を再決定し、
時間差を求め直して送信を再度試みる
ことを特徴とする通信方法。
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