JP2020150371A - Communication device - Google Patents

Abstract

To provide a communication device capable of restraining communication delay suitably in an on-vehicle network system including multiple buses.SOLUTION: A communication device is communicable with other communication device included in an on-vehicle network system including multiple buses, with more than one of the multiple buses as communication pathways. The communication device includes, for every more than one buses, a communication unit having a buffer for temporarily storing a message to be transmitted and received, a load detection section capable of detecting load of every more than one buses, on the basis of the number of messages stored in the buffer for a prescribed period or more, of more than one buses, and a bus selection part for selecting a bus of lowest load, out of the more than one buses, as the communication pathway for transmitting a message to other communication device, on the basis of the detection results from the load detection section.SELECTED DRAWING: Figure 3

Description

The present invention relates to a communication device constituting a network system mounted on a vehicle or the like.

The vehicle is equipped with a network system in which communication devices such as in-vehicle devices called a plurality of ECUs (Electronic Control Units) are connected to each other via a bus. Each ECU sends and receives messages on a frame-by-frame basis via a bus, acquires information from sensors provided in the vehicle, controls the sensors and actuators in the vehicle, and shares each function of the vehicle. And execute. The network system may have multiple buses. In addition, the network system may further include a relay device called a gateway. The gateway has a function of relaying frames between buses by transmitting frames received from one bus to another bus.

Various technologies have been proposed in such network systems. According to Patent Document 1, in a network system including two buses, when one of the buses fails, the communication device transmits only the communication data of a predetermined category, which is highly necessary, to the normal bus, and in the other category. It discloses that by suppressing the transmission of communication data, it is possible to reliably transmit communication data that is highly necessary.

In Patent Document 2, the communication device measures the load based on the integrated time when the message flows through the network within a predetermined period for load measurement, and when it is determined that the load is high, the transmission of the message is regulated. , Discloses that transmission regulation is performed according to the load.

Patent Document 3 discloses that each communication device counts the number of frames transmitted to the bus and notifies each other, and calculates the bus load based on the total number of frames transmitted to the bus per unit time. There is.

Patent Document 4 discloses that the gateway has a function of monitoring the bus load and adjusting the bus load.

Japanese Unexamined Patent Publication No. 2008-271040 International Publication No. 2013/136496 Japanese Unexamined Patent Publication No. 2012-231360 Japanese Unexamined Patent Publication No. 2006-287738

In network systems, it has been proposed to provide multiple buses with the aim of distributing the bus load and suppressing communication delays, but there is still room for improvement.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a communication device capable of suitably suppressing communication delay in an in-vehicle network system including a plurality of buses.

In order to solve the above problems, one aspect of the present invention is included in an in-vehicle network system including a plurality of buses, and another aspect of the present invention is included in the in-vehicle network system using two or more of the plurality of buses as communication paths. A communication device capable of communicating with a communication device, for each of two or more buses, two or more communication units having a buffer for temporarily storing messages to be sent and received, and two or more messages stored in the buffer for a predetermined period or longer. A load detector that can detect the load of two or more buses based on the number of buses, and the bus with the lowest load among the two or more buses based on the detection result of the load detector. It is a communication device including a bus selection unit as a communication path for transmitting a message to the communication device of.

As described above, according to the present invention, it is possible to provide a communication device capable of suitably suppressing communication delay in an in-vehicle network system including a plurality of buses.

Configuration diagram of the network system according to the embodiment of the present invention Functional block diagram of a communication device according to an embodiment of the present invention The figure which shows the process which concerns on one Embodiment of this invention The figure which shows the process which concerns on the reference example of this invention

(Embodiment)
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

<Composition>
FIG. 1 shows a part of the configuration of the network system 100 according to the present embodiment. The network system 100 is mounted on a vehicle as an example. As an example, the network system 100 includes a communication device 10, another communication device 20 that transmits / receives a message to / from the communication device 10, a first bus 1, a second bus 2, and a communication path of the communication device 10 and the other communication device 20. A third bus 3 and a relay device 30 are provided.

In the present embodiment, as an example, the communication device 10 is connected to the first bus 1 and the second bus 2, the relay device 30 is connected to the first bus 1 and the third bus 3, and the other communication device 20 is the second. It is connected to the bus 2 and the third bus 3. The network system 100 is connected to one or more of the first bus 1, the second bus 2, and the third bus 3 in addition to the communication device 10 and the other communication device 20, and communicates with the communication device 10. It may be equipped with one or more possible communication devices. The configuration of the network system 100 is not limited to this, and if the communication device 10 can use a plurality of buses as communication paths, the number of buses, the connection topology between the plurality of communication devices, and the presence / absence of a relay device are not limited. The network system 100 can perform communication by, for example, a method compliant with the CAN (Controller Area Network) standard.

FIG. 2 shows a functional block of the communication device 10. The communication device 10 includes an application execution unit 11, a load detection unit 12, a bus selection unit 13, a distribution unit 14, and a communication unit 15. The application execution unit 11 executes various application programs for vehicle control and the like.

The application execution unit 11 executes one or more applications by generating a transmission message to another communication device 20 or the like or receiving a received message from another communication device 20 or the like.

The load detection unit 12 detects the load of each bus (first bus 1 and second bus 2 in this embodiment) to which the communication device 10 is connected. The bus selection unit 13 selects a bus as a communication path for the transmitted message.

The distribution unit 14 passes the transmission message generated by the application execution unit 11 to the communication unit 15 described below, or acquires the received message received by the communication unit 15 and passes it to the application execution unit 11.

The communication unit 15 executes communication using each bus (first bus 1 and second bus 2) as a communication path. The communication unit 15 has one or more buffers called message boxes provided for each bus. The communication unit 15 stores the transmission message received from the distribution unit 14 in the message box of the bus selected by the bus selection unit 13. The communication unit 15 can transmit the transmitted message in the message box according to the communication standard, such as when the corresponding bus is in an empty state or when the priority is higher than other messages flowing on the bus. If so, send it to the bus and clear the sent message from the message box. If transmission is not possible, the communication unit 15 waits for transmission of the transmission message until transmission is possible. Further, the communication unit 15 stores the received message addressed to the communication device 10 received from each bus (first bus 1 and second bus 2) in a message box corresponding to the bus. When the distribution unit 14 acquires the received message from the message box, the communication unit 15 deletes the received message from the message box.

The functions of each part of the communication device 10 are realized by software and hardware. For example, the functions of the application execution unit 11, the load detection unit 12, and the bus selection unit 13 are realized by an application program that is software, a processor that is hardware, and a memory. Further, the function of the distribution unit 14 is executed by a middleware program which is software and a processor and memory which are hardware. The function of the communication unit 15 is executed by hardware such as a memory, a protocol controller, and a transceiver. Further, each program, processor, or the like may be provided to individually execute the functions of each part, or may be provided to collectively execute the functions of two or more parts.

<Processing>
The message transmission process according to the present embodiment will be described below. FIG. 3 shows a flowchart showing an example of the message transmission process according to the present embodiment.

(Step S101): The application execution unit 11 generates a transmission message to another communication device 20 or the like, and this process is started when a message transmission request is generated.

(Step S102): The load detection unit 12 detects the load of the bus currently selected as the communication path. For example, when the communication device 10 is connected to the first bus 1 or the second bus 2, and the first bus 1 is currently selected as the communication path of the transmission message, the load detection unit 12 of the first bus 1 Detect the load. The bus currently selected as the communication route may be a bus preset as a bus to be normally used, or a bus selected when this flow was executed last time.

The load detection method is not limited, but the following methods can be used, for example. The following is a load measurement method for the first bus 1. The load detection of the second bus 2 can be performed in the same manner.
(1) The first bus is based on the number of past transmitted messages that have not been transmitted to the first bus 1 even after a predetermined period of time has passed since they were stored in the message box of the first bus 1 of the communication unit 15. The load of 1 can be detected. It can be determined that the larger the number, the higher the load.

(2) In the network system 100, the message having the lowest priority among the transmitted messages is stored in the message box of the communication unit 15, and the time from the storage to the transmission to the first bus 1 (retention time). ), And the load of the first bus 1 can be detected based on the measured residence time. It can be determined that the longer the residence time, the higher the load. Further, as such a message, for example, in the case of the CAN standard, an NM frame that is periodically transmitted for the network management function can be used. By using the residence time of the message having the lowest priority, it is possible to more reliably detect the high load state of the bus as compared with the case of using the residence time of the message having a relatively high priority.

(3) The load of the first bus 1 is increased based on the number of reception flags indicating that the received message received from the first bus 1 by the communication unit 15 and stored in the message box has not yet been acquired by the distribution unit 14. Can be detected. It can be determined that the larger the number, the higher the frequency of receiving the received message and the higher the load with respect to the processing cycle of the distribution unit 14.

(4) The load on the first bus 1 can be detected based on the number of transmission flags indicating that there is a transmission message that has not been transmitted to the first bus 1 since it was stored in the message box. It can be determined that the larger the number, the larger the number of messages to be transmitted in the message box with respect to the processing cycle of the distribution unit 14, and the higher the load.

(5) A plurality of test messages are transmitted to the first bus 1 at intervals shorter than the transmission cycle of the transmitted message, and the first bus is based on the increase in the residence time of the transmitted message due to the transmission of the test message. The load of 1 can be detected. It can be determined that the larger the increase is, the higher the load is.

According to each of the above methods, it is easy to change the high load state of the bus to the conventional communication device by making a relatively small change without adding new hardware or making a relatively large modification of the software program. It can be made detectable. Further, in the cases of (1) to (4), there is no need to additionally send and receive messages for load measurement, and the amount of processing and the amount of communication are compared with the method of performing additional communication to measure the load. Can be suppressed from increasing.

(Step S103): When the load detection unit 12 determines that the load of the first bus 1 is higher than a certain level, the process proceeds to step S104. When the load detection unit 12 does not determine that the load of the first bus 1 is higher than a certain level, the bus selection unit 13 does not change the state in which the first bus 1 is selected as the communication path of the transmission message. In the case, the process proceeds to step S105.

(Step S104): The bus selection unit 13 selects the second bus 2 as the communication path of the transmitted message. In this flow, the communication path is switched in this way on the assumption that the load of the second bus 2 is lower than that of the first bus 1 without detecting the load of the second bus 2. However, if such an assumption is not appropriate due to the characteristics of the network system 100, the load detection unit 12 detects the load of the first bus 1 and the load of the second bus 2 instead of steps S102 to S104. The bus selection unit 13 may execute a process of selecting the one with the lower load as the communication path. When the communication device 10 is connected to three or more buses, the load detection unit 12 detects the load of the three or more buses, and the bus selection unit 13 detects the load of the three or more buses most. The one with a low load may be selected as the communication path.

(Step S105): The distribution unit 14 receives the transmission message generated by the application execution unit 11 and stores it in the message box corresponding to the selected bus of the communication unit 15 (distribution).

(Step S106): The communication unit 15 transmits the transmission message in the message box as soon as it becomes possible to transmit the transmission message to the selected bus according to the communication standard.

This completes the flow. The application execution unit 11 newly generates a transmission message, and each time a transmission request for the transmission message is generated, this flow is repeatedly executed.

(effect)
As described above, the communication device 10 according to the present invention avoids a bus having a high load among a plurality of buses and selects another bus as a communication path. As a result, the bus load can be suitably distributed and the message transmission delay can be suitably suppressed. Further, by adopting the load detection method described above, it is possible to easily detect a high load state of a bus without adding new hardware or making a relatively large modification of a software program to a conventional communication device. ..

(Reference example 1)
The present invention may be modified as follows. FIG. 4 shows a flowchart showing an example of the message transmission process according to this reference example. In this reference example, the communication device 10 does not have to include the load detection unit 12.

(Step S201): The application execution unit 11 generates a transmission message to another communication device 20 or the like, and this process is started when a transmission request for the transmission message is generated. In this reference example, the application execution unit 11 designates two or more of the plurality of buses to which the communication device 10 is connected as communication paths.

(Step S202): The distribution unit 14 receives the transmission message generated by the application execution unit 11 and stores it in the message box corresponding to the designated bus.

(Step S203): The communication unit 15 transmits the transmission message in the message box to the bus that can be transmitted earliest in accordance with the communication standard.

(Step S204): The distribution unit 14 detects the bus to which the transmission message is transmitted and notifies the application execution unit 11. The application execution unit 11 receives the notification and notifies the distribution unit 14 to cancel the transmission of the transmission message to the bus for which the transmission message has not been transmitted among the designated buses. The distribution unit 14 causes the communication unit 15 to cancel the transmission of the transmitted message based on the notification.

This completes the flow. This flow is repeated every time the application execution unit 11 newly generates a transmission message and a transmission request for the transmission message is generated.

In this reference example, the bus capable of transmitting the transmission message earliest can be set as the communication path without detecting the load of each bus (first bus 1 and second bus 2).

(Reference example 2)
The present invention may be modified as follows. In this reference example, the communication device 10 does not have to include the load detection unit 12. In this reference example, the application execution unit 11 sequentially selects each of the plurality of buses to which the communication device 10 is connected as a communication path. To do. In this reference example, the load of a plurality of buses can be distributed without detecting the load of each bus (first bus 1 and second bus 2).

In the above embodiments and reference examples, the reception order of the transmission messages in the communication device on the receiving side may not match the transmission order due to the change in the communication path. If the transmitted message contains control data that is meaningful in the order of transmission, but the order of transmission cannot be specified because the communication device on the receiving side cannot receive the message in the order of transmission, use at least a part of the transmitted messages for processing. May not be possible. Therefore, when transmitting such a transmitted message, the application execution unit 11 or the like adds information that can specify the transmission order of the transmitted message to the transmitted message in accordance with a standard called E2E (End-to-End communication protection). It is preferable to do so. As a result, even if the reception order is different from the transmission order, the communication device on the receiving side can specify the transmission order, and the present invention can be suitably applied.

In the above-described embodiment, for example, if the communication route is changed when the bus load is remarkably high, the frequency of bus changes is reduced so that the transmission order and the reception order of the transmitted messages do not match. It can be suppressed within the permissible range. If the frequency at which the transmission order and the reception order of the transmission messages do not match can be suppressed within an allowable range in this way, it is not necessary to add information that can specify the transmission order of the transmission message to the transmission message.

The present invention includes not only a communication device, but also a network system including the communication device, a communication method executed by each computer of the communication device, a communication program, a computer-readable non-temporary storage medium that stores the communication program, and a network system. It can be regarded as a vehicle or the like. The present invention can also be applied to network systems other than network systems mounted on vehicles.

The present invention is useful for network systems mounted on vehicles and the like.

1 1st bus 2 2nd bus 3 3rd bus 10 Communication device 11 Application execution unit 12 Load detection unit 13 Bus selection unit 14 Distribution unit 15 Communication unit 20 Communication device 30 Relay device 100 Network system

Claims (1)

A communication device included in an in-vehicle network system including a plurality of buses and capable of communicating with other communication devices included in the in-vehicle network system by using two or more of the plurality of buses as communication paths.
A communication unit having a buffer for temporarily storing messages to be sent and received for each of the two or more buses.
A load detection unit capable of detecting a load for each of the two or more buses based on the number of messages stored in the buffer for a predetermined period or longer for each of the two or more buses.
A communication device including a bus selection unit that uses the bus with the lowest load among the two or more buses as a communication path for transmitting a message to the other communication device based on the detection result of the load detection unit.

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