JP7679772B2 - COMMUNICATION SYSTEM, INFORMATION SENDING NODE, AND INFORMATION RECEIVING NODE - Google Patents

Description

This disclosure relates to technology for communicating using communication frames in a communication system.

Patent Document 1 describes a method of adding padding, which is meaningless data (such as 0), to adjust message data to a certain length when communicating message data in a communication system that is installed in a vehicle and conforms to the CAN protocol. CAN is a registered trademark.

US Publication No. 2007091932

In-vehicle communication systems installed in vehicles are increasingly adopting CAN FD, which can communicate more data at higher speeds than CAN, as the amount of data communication increases. CAN FD stands for CAN with Flexible Data Rate. For example, a CAN FD communication device compatible with CAN FD can be configured to receive CAN communication frames from a CAN communication device compatible with another CAN. A CAN FD communication device can also be configured to collect message data and the like contained in multiple CAN communication frames, generate new message data, and transmit it in a CAN FD communication frame. A predetermined message identifier is assigned to the CAN FD communication frame containing the new message data.

However, in such an in-vehicle communication system, it is considered that a situation will arise in which multiple CAN communication frames are not transmitted at the same timing to the CAN FD communication device that collects and manages the message data, etc. contained in the multiple CAN communication frames. For this reason, in the above-mentioned CAN FD communication device, it is considered that a situation will arise in which, for example, even CAN FD communication frames to which the same message identifier is assigned have a data area length that includes CAN message data, etc., that differs depending on the timing. In other words, even if the CAN FD communication frames are assigned the same message identifier, it is considered that a situation will arise in which the padding amount, which is the data length of the padding to be added, differs depending on the timing, because the length of the determined data area differs depending on the timing.

For example, if the new message data described above has a predetermined data length and is not variable, in a CAN FD communication frame that stores the new message data in its data area, it is possible to achieve a one-to-one correspondence between the assigned message identifier and the amount of padding. However, as described above, in a CAN FD communication frame in which the data length of the new message data included in the data area is variable depending on the timing, a situation may arise in which it is difficult to achieve a one-to-one correspondence between the message identifier and the amount of padding.

In a CAN FD communication frame in which the data length of message data contained in such a data area varies depending on the timing, it is difficult to establish a one-to-one correspondence between message identifiers and padding amounts, and it takes time to identify the padding amount. If it takes time to identify the padding amount, a problem may arise in that it takes time to verify the message data when message authentication is performed on the message data contained in the data area of the CAN FD communication frame.

One aspect of the present disclosure provides a technique for relatively shortening the time required to determine the amount of padding in a data area in a communication frame in which the length of the data area varies due to the inclusion of message data with a variable data length.

One aspect of the present disclosure is a communication system (1) including a plurality of nodes connected to each other. In the communication system, at least one of the nodes is an information transmitting node (10i_1), and at least one of the nodes other than the information transmitting node is an information receiving node (10i_2) communicatively connected to the information transmitting node. The information transmitting node includes a generating unit (133) and a transmitting unit (12i). The generating unit is configured to generate a communication frame that conforms to a predetermined communication protocol.

The transmission unit is configured to transmit the communication frame generated by the generation unit. The generation unit includes a management unit (S10), a replenishment execution unit (S20, S30), and a replenishment information unit (S40). The management unit is configured to generate a management message and store the generated management message in the data area of the communication frame. The management message includes at least one individual message data. The individual message data is data generated by at least one of the multiple nodes, and the data length is variable within a predetermined range.

The supplement execution unit is configured to determine the data length of the supplement data and store the supplement data of the determined data length in the data area. The supplement data is data for making the data area (103) equal to a specified data length according to the data length of the management message. The supplement information unit is configured to store supplement information indicating the data length of the supplement data in a predetermined position in the data area.

The information receiving node includes a receiving unit (12i) and an identifying unit (134). The receiving unit is configured to receive a communication frame. The identifying unit is configured to identify the data length of the supplementary data in the communication frame received by the receiving unit. The identifying unit also includes a supplementary identifying unit (S110) configured to acquire supplementary information included in the data area of the communication frame and identify the data length of the supplementary data based on the supplementary information.

With this configuration, the information receiving node can easily identify the data length of the supplementary data by obtaining the supplementary information from the communication frame. In other words, in a communication frame in which the length of the data area varies due to the inclusion of one or more individual message data, the time required to identify the data length of the supplementary data in the data area can be relatively shortened.

As one aspect of the present disclosure, the present disclosure may be understood as an information transmission node constituting the above-mentioned communication system.
As one aspect of the present disclosure, the present disclosure may be understood as an information receiving node constituting the above-mentioned communication system.

FIG. 2 is a block diagram showing the configuration of a communication system and each node (i.e., ECU). FIG. 2 is an explanatory diagram illustrating a frame format of a CAN FD communication frame. FIG. 11 is an explanatory diagram illustrating an example of a management message in a CAN FD communication frame to which the same CAN-ID is assigned. FIG. 11 is an explanatory diagram illustrating an example of specifying a padding amount. 13 is a flowchart of a transmission process. FIG. 4 is a block diagram illustrating a transmission process. FIG. 11 is an explanatory diagram showing a padding information area in a CAN FD data area. 13 is a flowchart of a receiving process. FIG. 4 is a block diagram illustrating a receiving process. FIG. 11 is an explanatory diagram showing a padding information area in a CAN FD data area in another embodiment. FIG. 11 is an explanatory diagram showing a padding information area in a CAN FD data area in another embodiment. FIG. 11 is an explanatory diagram showing a padding area in a CAN FD data area in another embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[Embodiment]
[1. Configuration]
1, the communication system 1 is mounted on a vehicle and includes a plurality of nodes 10 and a bus-like communication path 3 that connects the nodes 10 to each other. In the communication system 1, CAN (hereinafter also referred to as Classic CAN) and CAN FD are used as communication protocols.

The node 10 is also called an electronic control unit (hereinafter, also referred to as ECU 10). ECU is an abbreviation of Electronic Control Unit. Hereinafter, one of the ECUs 10 in the communication system 1 is called management ECU 10i_1, one of the ECUs 10 other than management ECU 10i_1 is called management ECU 10i_2, and the other nodes 10 are called normal ECU 10n. Normal ECU 10n includes normal ECU 10n_1 and normal ECU 10n_2. Hereinafter, when there is no particular distinction between individual elements, such as normal ECU 10n_1 and normal ECU 10n_2, the subscripts will be omitted and they will simply be called ECU 10n. Note that the number of ECUs 10, the number of normal ECUs 10n, and the number of management ECUs 10i in the communication system 1 are not limited to the example shown in FIG. 1.

[1-1. Normal ECU]
The normal ECU 10n includes a control unit 11n, a communication controller 12n, and a message processing unit 13n.

The communication controller 12n includes a CAN controller capable of communicating via CAN (i.e., Classic CAN). When the CAN controller receives a communication frame (hereinafter, CAN communication frame) according to the CAN protocol, to which a CANID to be received by its own ECU 10n is assigned, from the communication path 3, it extracts message data (hereinafter, also referred to as a message). A message is data included in the data area of a communication frame, and is meaningful data, unlike padding, which will be described later.

Hereinafter, the message contained in the CAN communication frame is also referred to as the CAN message. Here, the frame format of the CAN communication frame is not illustrated, but the CAN message is contained in the data area of the CAN communication frame (hereinafter also referred to as the CAN data area). The data length of the CAN data area is variable within 8 bytes, with a maximum value of 8 bytes. The CAN controller supplies the extracted CAN message to the message processing unit 13n.

The communication controller 12n also transmits various messages supplied from the message processing unit 13n to the communication path 3 via a CAN communication frame. A message identifier (hereinafter also referred to as a CANID) according to the type of message is assigned to the CAN communication frame. The CANID is stored in the CANID area of the CAN communication frame. Note that a data length code (hereinafter also referred to as a CAN_DLC) indicating the data length of the CAN data area is stored in the DLC area of the CAN communication frame. DLC is an abbreviation for Data Length Code. The data length of the DLC is, for example, 4 bits.

The control unit 11n includes a microcomputer, similar to the control unit 11i described below. The control unit 11n executes various processes to realize functions that have been assigned to the ECU 10n in advance by communicating with other ECUs 10 via the message processing unit 13n and the communication controller 12n.

Like the message processing unit 13i described below, the message processing unit 13n is configured mainly around a microcomputer. The message processing unit 13n includes a normal transmission/reception processing unit 131 as a functional configuration realized by the CPU of the microcomputer executing a program. The normal transmission/reception processing unit 131 executes a process of receiving a CAN message from another ECU 10 using a CAN communication frame. The normal transmission/reception processing unit 131 also executes a process of transmitting a CAN message to another ECU 10 using a CAN communication frame.

[1-2. Management ECU]
The management ECU 10i includes a control unit 11i, a communication controller 12i, a message processing unit 13i, and a key holding unit 14i.

The communication controller 12i includes a controller (hereinafter, CAN FD controller) capable of communicating using both CAN (i.e., Classic CAN) and CAN FD communication protocols. When the CAN FD controller receives a communication frame with a CANID assigned to be received by its own ECU 10i from the communication path 3, it extracts a message and supplies it to the message processing unit 13i. The received communication frame may be a CAN communication frame or a communication frame by CAN FD (hereinafter, also referred to as a CAN FD communication frame). As described above, the received communication frame is assigned a CANID according to the type of message.

For example, when the communication controller 12i receives a CAN communication frame, it supplies the extracted message to the normal transmission/reception processing unit 131 of the message processing unit 13i. Also, when the communication controller 12i receives a CAN FD communication frame, it supplies the extracted message to the management reception processing unit 134 of the message processing unit 13i.

The communication controller 12i also transmits various messages supplied from the message processing unit 13i on a CAN communication frame or a CAN FD communication frame to the communication path 3. For example, the communication controller 12i may output various messages supplied from the normal transmission/reception processing unit 131 of the message processing unit 13i on a CAN communication frame to the communication path 3. For example, the communication controller 12i may also output various messages supplied from the management transmission processing unit 133 of the message processing unit 13i on a CAN FD communication frame to the communication path 3.

The key holding unit 14i includes a readable and writable non-volatile memory. The key holding unit 14i stores a so-called MAC key K used to generate a message authentication code (hereinafter, MAC). MAC is an abbreviation for Message Authentication Code, and is information (hereinafter, also referred to as an authenticator) for detecting data errors and tampering. The MAC key K is common to all management ECUs 10i that transmit and receive CAN FD communication frames, and is pre-stored in the key holding unit 14i.

The control unit 11i includes a microcomputer. The control unit 11i executes various processes to realize functions that have been assigned to the ECU 10i in advance by communicating with other ECUs 10 via the message processing unit 13i and the communication controller 12i.

The message processing unit 13i is mainly composed of a microcomputer having a CPU and semiconductor memory such as RAM, ROM, and flash memory (hereinafter referred to as memory). The various functions of the control unit 11i are realized by the CPU executing a program stored in a non-transitive physical recording medium. In this example, the memory corresponds to the non-transitive physical recording medium storing the program. Furthermore, the execution of this program results in the execution of a method corresponding to the program. The number of microcomputers constituting the control unit 11i may be one or more.

The message processing unit 13i includes a normal transmission/reception processing unit 131, a management transmission processing unit 133, and a management reception processing unit 134 as functional components realized by the CPU executing a program. The normal transmission/reception processing unit 131 is the same as that of the normal ECU 10n described above. In other words, the message processing unit 13i of this embodiment has the functions of transmitting and receiving communication frames via CAN FD, such as the management transmission processing unit 133 and the management reception processing unit 134, added to the message processing unit 13n described above.

As described above, the normal transmission/reception processing unit 131 executes the process of receiving CAN messages by CAN communication frames from other ECUs 10. The normal transmission/reception processing unit 131 also executes the process of transmitting CAN messages by CAN communication frames to other ECUs 10.

The management transmission processing unit 133 generates a new message (hereinafter also referred to as a management message) including a message contained in a CAN communication frame received from one or more other ECUs 10. The management transmission processing unit 133 executes a process of transmitting a message by a CAN FD communication frame to another management ECU 10i (e.g., management ECU 10i_2 when the own ECU 10i is management ECU 10i_1). The management reception processing unit 134 executes a process of receiving a message by a CAN FD communication frame from another management ECU 10i (e.g., management ECU 10i_1 when the own ECU 10i is management ECU 10i_2). Details of these processes will be described later.

[1-3. Communication system]
In this embodiment, the communication system 1 is, for example, a system for controlling an engine (not shown) mounted in a vehicle.

For example, the normal ECU 10n_1 has a function of detecting the temperature of the coolant in the engine based on the output from a temperature sensor (not shown) and outputting the detection result. The normal ECU 10n_1 generates a CAN communication frame (hereinafter, Classic CAN A frame) including data indicating the detected water temperature as a message in the CAN data area, and outputs the frame to the communication path 3. The normal ECU 10n_1 outputs the Classic CAN A frame at a predetermined period (hereinafter, first period T1). The Classic CAN A frame is assigned ID_A as a CANID. In the Classic CAN A frame, data (i.e., DLC) indicating the data length of the CAN data area (e.g., DLC_A) is stored in the DLC area (hereinafter, also referred to as the CAN_DLC area). DLC here indicates the data length of the CAN data area.

The normal ECU 10n_2 has a function of detecting the vehicle speed based on the output from a wheel speed sensor (not shown). The normal ECU 10n_2 generates a CAN communication frame (hereinafter, Classic CAN B frame) including data indicating the detected vehicle speed as a message in the CAN data area, and outputs it to the communication path 3. The normal ECU 10n_2 outputs the Classic CAN B frame at a predetermined period (hereinafter, second period T2). The Classic CAN B frame is assigned ID_B as a CANID. In the Classic CAN B frame, DLC indicating the data length of the CAN data area (e.g., DLC_B) is stored in the CAN_DLC area.

The management ECU 10i_1 (e.g., the control unit 11i_1) detects the engine speed based on the output from a crank angle sensor (not shown) or the like. The management ECU 10i_1 (e.g., the normal transmission/reception processing unit 131) may generate a CAN communication frame (hereinafter, Classic CAN C frame) including data indicating the detected engine speed as a message in the CAN data area. Then, the management ECU 10i_1 (e.g., the communication controller 12i) may output the generated Classic CAN C frame to the communication path 3. The management ECU 10i_1 may output the Classic CAN C frame at a predetermined period (hereinafter, the third period T3). For example, the second period T2 may be shorter than the first period T1, and the third period T3 may be shorter than the first period T1 and the second period T2 (i.e., T1>T2>T3). A Classic CAN C frame is assigned ID_C as the CANID. In a Classic CAN C frame, a DLC indicating the data length of the CAN data area (e.g., DLC_C) is stored in the CAN_DLC area.

The management ECU 10i_1 may also have a function of collecting (i.e., managing) messages contained in the received Classic CAN A and B frames and the generated Classic CAN C frames, as shown in FIG. 2 described later. Specifically, the management ECU 10i_1 (e.g., the management transmission processing unit 133) generates a CAN FD communication frame that includes the above-mentioned management messages, including the received Classic CAN A and B frames and the generated Classic CAN C frame messages, in the CAN FD data area 103. Then, the management ECU 10i_1 (e.g., the communication controller 12i) outputs the CAN FD communication frame to the communication path 3. The CAN FD data area 103 refers to the data area of the CAN FD communication frame. The CAN FD communication frame is assigned ID_D as the CANID.

For example, the management message includes at least one individual message. The individual message is data generated by each ECU 10, and includes the CANID, DLC, and message of each CAN communication frame in each ECU 10. For example, the data length is fixed in advance, such as 3 bytes for the CANID and 1 byte for the DLC, and the data length of the message can be variable, such as 0 to 8 bytes. In other words, the data length of the individual message is variable within a predetermined range (for example, 4 to 12 bytes).

The management ECU 10i_1 may generate and output the CAN FD communication frame at a predetermined period (hereinafter, the fourth period T4). For example, in this embodiment, the fourth period T4 may be the same as the third period T3 (i.e., T3 = T4).

The management ECU 10i_2 (e.g., the communication controller 12i) receives a CAN FD communication frame (e.g., a CAN FD communication frame to which ID_D is assigned as the CAN ID) from the management ECU 10i_1. The management ECU 10i_2 (e.g., the management reception processing unit 134) extracts an individual message from the management message contained in the CAN FD data area 103 of the CAN FD communication frame, and detects various detection data (i.e., messages) such as water temperature, vehicle speed, engine speed, etc. contained in the individual message. Then, the management ECU 10i_2 (e.g., the control unit 11i_2) controls the engine based on the various detection data.

[1-4. CAN FD communication frame]
The management ECU 10i_1 generates a CAN FD communication frame that conforms to the CAN FD frame format. As shown in Fig. 2, the CAN FD communication frame includes a CAN ID area 101, a DLC area 102, a CAN FD data area 103, and the like.

The CANID field 101 is an area that indicates the CANID of the CAN FD communication frame (i.e., includes the CANID). For example, the CAN FD communication frame generated by the above-mentioned management ECU 10i_1 includes data indicative of ID_D as the CANID in the CANID field 101.

The DLC area 102 is an area where DLC is stored. DLC here indicates the data length of the CAN FD data area 103 of the CAN FD communication frame, and is represented by 4 bits. The data length of the CAN FD data area 103 can take values such as 0 to 8, 12, 16, 20, 24, 32, 48, and 64 bytes.

The CAN FD data area 103 is an area that includes various data. For example, the CAN FD data area 103 includes a management message area 201, a padding area 202, and an authenticator area 203. The management message area 201 is an area that includes management messages. As described above, the management messages include individual messages for each CAN communication frame.

The authenticator area 203 is an area in which data indicating a MAC is stored as a verification expected value (i.e., an authenticator) for verifying that there are no errors or tampering in the management message of the CAN FD communication frame. The authenticator area 203 may have a predetermined data length. The data length of the authenticator area 203 is called the authenticator data length. The authenticator data length may be, for example, 10 bytes. However, the authenticator data length is not limited to this.

However, in the communication system 1, the multiple CAN communication frames transmitted from each ECU 10 are not necessarily transmitted at the same (i.e., always aligned) timing to the management ECU 10i_1 that collects messages from the multiple CAN communication frames. Factors that cause the timing to not match include, for example, differences in the first period T1, second period T2, and third period T3 that are the transmission periods of each CAN communication frame from each normal ECU 10n_1, 10n_2 and management ECU 10i_1. Another factor that causes the timing to not match is that a situation may arise in which each CAN communication frame is not output to the communication path 3 according to the transmission period due to the arbitration state of the communication path 3.

In other words, in the management ECU 10i_1, for example, as shown in FIG. 3, in a CAN FD communication frame to which the same CAN ID (e.g., ID_D) is assigned, a situation may occur in which the data length of the management message in the CAN FD data area 103 (hereinafter, the management message length) varies depending on the timing.

As a result, even if the same CAN ID (e.g., ID_D) is assigned to a CAN FD communication frame, a situation may arise in which the length of the CAN FD data field 103 (i.e., the designated data length, hereinafter) is determined differently depending on the timing. In addition, a situation may arise in which the data length of the padding to be added (hereinafter, the padding amount) is different depending on the timing. Depending on the timing, a situation may also arise in which no padding is added (i.e., in other words, padding with a padding amount = 0 is added).

Padding refers to meaningless data that is added to the CAN FD data area 103 to make it a certain length (i.e., a determined length that the CAN FD data area 103 can take). Padding can be, for example, 0.

In this way, identifying the amount of padding in a CAN FD communication frame in which the same CANID is assigned and the length of the CAN FD data area 103 changes due to the inclusion of a management message whose data length is variable within a predetermined range places a load on the CPU and takes time to identify. For example, this is because it is necessary to execute a search process as described below.

[1-5. Example of specifying padding amount]
For example, in order to identify the amount of padding, it is possible to execute a search process as shown in Fig. 4. In the search process, first, in the above-mentioned CAN FD communication frame (i.e., to which ID_D is assigned), the authenticator data length is subtracted from the data length indicated by the DLC (i.e., (1) in the figure). This identifies how many bytes the data length (hereinafter also referred to as adjustment data length) of the data including the management message and padding (hereinafter also referred to as adjustment data) is.

Next, the start position of the CAN FD data area 103 is set as the search position, and 3 bytes of data are obtained from the search position, and search position = search position + 3 bytes. It is determined whether the obtained 3 bytes of data are a valid value as a CANID (i.e., (2) in the figure). A valid value as a CANID is, for example, a value that is not 0. If the value is valid as a CANID, then the DLC in the CAN communication frame is obtained (i.e., (3) in the figure). Next, search position = search position + 1 byte, and further search position = search position + data length indicated by DLC.

Next, if the value obtained by subtracting the current search position from the adjusted data length is greater than 4 bytes, the next 3 bytes of data (i.e., the CANID of the next CAN communication frame) are obtained from the search position (i.e., (4) in the diagram). (2)-(4) are then repeated (i.e., (5) in the diagram). Next, if the obtained 3 bytes of data are 0 (i.e., CANID = 0x00), or if the value obtained by subtracting the current search position from the adjusted data length is less than 4 bytes, the search is terminated (i.e., (6) in the diagram).

As a result, the value obtained by subtracting the final search position in (6) from the adjusted data length corresponds to the amount of padding (i.e., (7) in the figure). In other words, for example, in order to determine the amount of padding in this way, a load is placed on the CPU, and a certain amount of calculation time is required.

2. Processing
In the communication system 1, the management ECUs 10i_1 and 10i_2 use a CAN FD communication frame that includes a padding information area 204 for storing data indicating a padding amount (hereinafter, padding information) at a predetermined position in the CAN FD data area 103. The processes executed by the management ECUs 10i_1 and 10i_2 will be described below.

[2-1. Transmission process]
The transmission process executed by the management ECU 10 (e.g., the management ECU 10i_1) will be described with reference to Figs. 5, 6, and 7. The management ECU 10i_1 (e.g., the management transmission processing unit 133 included in the message processing unit 13i) executes the transmission process every fourth period T4 that is determined in advance. For example, in this embodiment, the fourth period T4 is equal to the third period T3 (i.e., T1>T2>T3=T4). That is, the management ECU 10i_1 may be configured to execute the transmission process every time it transmits a Classic CAN C frame in the third period T3.

First, in S10, the management ECU 10i_1 generates a management message. The management message includes at least one of the individual messages described above, whose data length is variable within a predetermined range. The predetermined range may be, for example, a range of 4 to 12 bytes, since the CANID is 3 bytes, the DLC is 1 byte, and the data length in the CAN data area is 0 to 8 bytes. Variable data length here means that the data length in the CAN data area may differ for each ECU 10, that is, for each CAN communication frame received from each ECU 10. The individual message is data generated by each node 10 (i.e., another ECU 10 or the own node 10i).

For example, the management ECU 10i_1 may store in memory a CAN communication frame received from another node 10 or transmitted by the management ECU 10i_1 itself through a process separate from this transmission process. In this embodiment, since T1>T2>T3=T4, at the time of this step, a Classic CAN C frame is always stored in the memory.

When the second period T2 and the third period T3 coincide, the memory also stores Classic CAN B frames (i.e., Classic CAN B and C frames). When the first period T1 and the third period T3 coincide, the memory also stores Classic CAN A frames (i.e., Classic CAN A and C frames). When the first period T1 and the second period T2 and the third period T3 coincide, the memory also stores Classic CAN A, B, and C frames.

In this step, the management ECU 10i_1 extracts the CANID, DLC, and a message contained in the CAN data area (hereinafter, the CAN message) from the CAN communication frame (i.e., at least one of the Classic CAN A, B, and C frames) stored in the memory, and generates a management message. As a result, the management message always contains the CANID, DLC, and CAN message extracted from the Classic CAN C frame, as shown in FIG. 3 above. Depending on the timing, the management message may further contain the CANID, DLC, and CAN message extracted from at least one of the Classic CAN A and B frames.

Note that, taking into account the arbitration state in the communication path 3, the management ECU 10i_1 may wait for a predetermined period of time in this step, and then generate (i.e., extract) individual data from the Classic CAN frame stored in the memory and generate a management message.

The management ECU 10i_1 generates a management message and stores it in memory, determines the management message length, which is the data length of the generated management message, and stores the determined management message length in memory.

Next, in S20, the management ECU 10i_1 determines the amount of padding. To determine the amount of padding, the management ECU 10i_1 first determines the data length of the CAN FD data area 103 (hereinafter also referred to as the designated data length). The designated data length refers to the data length of the CAN FD data area 103 that includes the generated management message.

Specifically, the management ECU 10i_1 calculates the data length of the valid message (hereinafter, the valid message length). The valid message is data obtained by adding the variable (i.e., changing depending on the timing of generating the management message) management message length and the fixed value authentication code data length and data length of the padding information area 204. The management ECU 10i_1 determines, as the specified data length, the data length that is equal to or greater than the valid message length and closest to the valid message length among the possible data lengths of the CAN FD data area 103, 0 to 8, 12, 16, 20, 24, 32, 48, and 64 bytes. The possible data lengths of the CAN FD data area 103, 0 to 8, 12, 16, 20, 24, 32, 48, and 64 bytes, are also referred to as data length candidate values. The management ECU 10i_1 may store data indicating the determined specified data length in memory in order to generate a CAN FD communication frame (i.e., store it in the DLC area 102).

The management ECU 10i_1 subtracts the effective message length from the determined specified data length, and identifies the data length resulting from the subtraction as the padding amount. The padding amount may be expressed in bytes, for example, 8 bytes, 2 bytes, 0 bytes, etc.

In the next step S30, the management ECU 10i_1 stores the padding amount in the CAN FD data area 103, for example, in an area between the management message area 201 and the authenticator area 203. Hereinafter, the area in which the padding is stored is also referred to as the padding area 202.

Next, in S40, the management ECU 10i_1 designates a predetermined position in the CAN FD data area 103 as the padding information area 204, and stores the padding information in the padding information area 204. In this embodiment, as shown in FIG. 7, the padding information area 204 is included at the beginning of the CAN FD data area 103. The data length of the padding information (i.e., the data length of the padding information area 204) is 4 bits as described above, and for example, when the padding amount is 8 bytes, "1000" is stored in the padding information area 204 as the padding information indicating the padding amount.

In the following S50, the management ECU 10i_1 calculates a MAC from the management message and the MAC key K.
Next, in S60, the management ECU 10i_1 stores data indicating the MAC calculated in S40 in the authenticator area 203.

In the next step S70, the management ECU 10i_1 outputs the CAN FD communication frame to the communication path 3. For example, the management ECU 10i_1 causes the communication controller 12i to generate a CAN FD communication frame including a CAN ID field 101, a DLC field 102, etc., for the CAN FD data field 103 generated in steps S10-S60. The communication controller 12i stores data indicating ID_D in the CAN ID field 101, and stores data indicating the determined specified data length in the DLC field 102. The management ECU 10i_1 causes the communication controller 12i to output the generated CAN FD communication frame to the communication path 3. The management ECU 10i_1 then ends the transmission process.

[2-2. Reception processing]
Next, the reception process executed by the management ECU 10i (e.g., the management ECU 10i_2) will be described with reference to Fig. 7, Fig. 8, and Fig. 9. The management ECU 10i_2 (e.g., the management reception processing unit 134 included in the message processing unit 13i) executes this reception process when it receives a CAN FD communication frame of a predetermined CAN ID (e.g., the above-mentioned ID_D). Note that the management ECU 10i_2 may execute this reception process after storing the received CAN FD communication frame in a memory.

First, in S110, the management ECU 10i_2 acquires padding information from the padding information area 204 and identifies the amount of padding. Specifically, the management ECU 10i_2 extracts data from the padding information area 204 in the CAN FD data area 103 (i.e., the first 4 bits of data) as padding information and identifies the amount of padding indicated by the padding information.

Next, in S120, the management ECU 10i_2 identifies the data length of the management message. Specifically, the management ECU 10i_2 identifies the designated data length based on the DLC included in the DLC area 102 of the received CAN FD communication frame. The management ECU 10i_2 calculates the data length of the management message by subtracting the amount of padding identified in S120, the data length of the MAC as an authenticator (e.g., 10 bytes), and the data length of the padding information (e.g., 4 bits) from the designated data length.

In the next step S130, the management ECU 10i_2 uses the subtraction value calculated in S120 to identify the management message contained in the CAN FD data area 103. For example, the management ECU 10i_2 determines the position in the CAN FD data area 103 excluding the padding information area 204 (i.e., 4 bits) as the start position, and identifies the data contained in the area from the start position to a position obtained by adding the specified data length as the management message.

Next, in S140, the management ECU 10i_2 calculates a MAC (hereinafter, a comparison MAC) as a new authenticator using the management message identified in S130 and the MAC key K prestored in the key holding unit 14i, and stores the calculated comparison MAC in memory.

In the next step S150, the management ECU 10i_2 compares the MAC calculated in S140 with the MAC included in the authenticator area 203 of the CAN FD data area 103 of the received CAN FD communication frame. If the comparison results in a match, the management ECU 10i_2 extracts various individual messages from the management message received and stored in memory, and extracts the CAN messages (i.e., various detection results) included in the individual messages. This causes the control unit 11i to perform various controls based on the various detection results. On the other hand, if the comparison results are not a match, the management ECU 10i_2 discards the management message stored in memory. The management ECU 10i_2 then ends this reception process.

3. Effects
According to the first embodiment described above in detail, the following effects are achieved.
(3a) The communication system 1 includes a plurality of ECUs 10 connected to each other. At least one of the plurality of nodes 10 is a management ECU 10i_1, and at least one of the plurality of nodes 10 other than the management ECU 10i_1 is a node management ECU 10j connected to the management ECU 10i_1 so as to be able to communicate with each other.

The management ECU 10i_1 includes a management transmission processing unit 133 that generates a CAN FD communication frame, and a communication controller 12i that transmits the CAN FD communication frame.
In S10, the management transmission processing unit 133 generates a management message and stores the generated management message in the data area 103 (i.e., the management message area 201) of the CAN FD communication frame. In S20, the management transmission processing unit 133 determines the data length of padding (i.e., the padding amount) that is supplementary data for making the CAN FD data area 103 equal to a designated data length according to the data length of the management message. In S30, the management transmission processing unit 133 stores padding of the determined padding amount in the CAN FD data area 103. In S40, the management transmission processing unit 133 stores padding information indicating the padding amount in a predetermined position in the CAN FD data area 103.

The management ECU 10i_2 includes a communication controller 12i that receives a CAN FD communication frame, and a management reception processing unit 134 that identifies the amount of padding. In S110, the management reception processing unit 134 acquires padding information included in the CAN FD data area 103 of the CAN FD communication frame, and identifies the amount of padding based on the padding information.

As a result, the ECU 10i (i.e., the management ECU 10i_2) that receives the CAN FD communication frame can easily identify the amount of padding by extracting padding information from the CAN FD communication frame. In other words, in a CAN FD communication frame in which the length of the CAN FD data area 103 varies due to the inclusion of one or more individual messages, the time required to identify the amount of padding in the CAN FD data area 103 can be relatively shortened.

(3b) In the management ECU 10i_1, the management transmission processing unit 133 generates a MAC as an authenticator in S50 and S60, and stores the generated MAC in the CAN FD data area 103. In the management ECU 10i_2, the management reception processing unit 134 calculates the data length of the management message as a subtraction value obtained by subtracting the padding amount, the data length of the authenticator, and the data length of the padding information from the specified data length in S120. In S130, the management reception processing unit 134 uses the subtraction value to identify the management message included in the CAN FD data area 103.

As a result, when an authenticator is included, the time required to identify the amount of padding is shortened, and the time required to identify the management message itself contained in the CAN FD data area 103 is also shortened.

(3c) In the management ECU 10i_2, the management reception processing unit 134 generates a comparison MAC in S140 based on the identified management message and the MAC key K as an authentication key stored in the key holding unit 14i. In S150, the management reception processing unit 134 compares the generated comparison MAC with the MAC included in the received CAN FD communication frame to determine whether the management message has been tampered with.

This reduces the time required to determine whether a management message has been tampered with when it contains an authenticator, by shortening the time it takes to identify the amount of padding and the time it takes to identify the management message itself.

(3d) In S20, the management transmission processing unit 133 of the management ECU 10i_1 calculates the effective message length, which is the sum of the management message length, the authenticator data length, and the data length of the padding information area 204. The management transmission processing unit 133 determines, as the designated data length, the data length that is equal to or greater than the effective message length and closest to the effective message length among multiple data length candidate values for the data length of the data area 103. Even for such a CAN FD communication frame in which the data length of the CAN FD data area 103 is variable depending on the data length of the management message length, the management ECU 10i_2 can easily identify the padding amount. As a result, the time required to identify the padding amount can be relatively shortened.

(3e) The management ECU 10i_1 stores the padding information area 204 indicating the padding information at the beginning of the CAN FD data area 103. By storing the padding information area 204 indicating the padding information at the beginning of the CAN FD data area 103, the management ECU 10i_2 can more easily identify the padding amount.

(3f) CAN FD communication frames having different lengths of the CAN FD data area 103 due to including one or more individual messages are assigned the same CANID as a predetermined message identifier. That is, in S10, in the management ECU 10i_1, the management transmission processing unit 133 stores the generated management message in the data area 103 of the CAN FD communication frame to which the same predetermined message identifier is assigned. In the management ECU 10i_2, the communication controller 12i acquires the CAN FD communication frame to which the same message identifier is assigned as described above as a CAN FD communication frame to be received by the management ECU 10i_2.

Even for such CAN FD communication frames in which the CAN ID and the amount of padding in the CAN FD data area 103 do not correspond one-to-one, the management ECU 10i_2 can easily identify the amount of padding.

(3g) Among the multiple ECUs 10, the remaining ECUs 10 other than the management ECU 10i_1 and the management ECU 10i_2 are normal ECUs 10n. In the management ECU 10i_2, the management reception processing unit 134 receives at least a CAN FD communication frame conforming to CAN FD as a first communication protocol. In the management ECU 10i_1, the management transmission processing unit 133 transmits at least a CAN FD communication frame. The management ECU 10i_1 further includes a normal transmission/reception processing unit 131. The normal transmission/reception processing unit 131 transmits and receives a CAN communication frame conforming to CAN as a second communication protocol, which has a shorter data area than the CAN FD communication frame.

The management transmission processing unit 133 generates a management message that includes, as an individual message, a CAN message included in a CAN communication frame received from a plurality of normal ECUs 10n that are normal ECUs 10n and transmit and receive CAN communication frames. The management transmission processing unit 133 generates the management message at a predetermined transmission period (for example, the fourth period T4 described above).

In such a communication system 1, a situation may arise in which multiple CAN communication frames are not transmitted to the management ECU 10i_1 equipped with the management transmission processing unit 133 at the same time. In other words, a situation may arise in which there is no one-to-one correspondence between the message identifier and the padding amount. In the communication system 1 of this embodiment, even in a situation in which there is no one-to-one correspondence between the CAN ID of the CAN FD communication frame as the message identifier and the padding amount, the padding amount can be easily identified based on the padding information as described above.

(3h) The management ECU 10i_1 includes a communication controller 12i that receives CAN FD communication frames, and the above-mentioned management reception processing unit 134. The management ECU 10i_2 includes a communication controller 12i that transmits CAN FD communication frames, and the above-mentioned management transmission processing unit 133. As a result, in the communication system 1, for example, the management ECU 10i_1 can execute the functions of the management ECU 10i_1, and the management ECU 10i_2 can execute the functions of the management ECU 10i_2.

In the above embodiment, the management ECU 10i_1 corresponds to an information transmission node, and the management ECU 10i_2 corresponds to an information reception node. The communication controller 12i corresponds to a transmission unit and a reception unit. The management transmission processing unit 133 corresponds to a generation unit, a management unit, a replenishment execution unit, a replenishment information unit, and an authentication information unit, and S10 corresponds to processing as the management unit, S20 and S30 correspond to processing as the replenishment execution unit, and S40 corresponds to processing as the replenishment information unit. S50 and S60 correspond to processing as the authentication information unit.

The management reception processing unit 134 corresponds to the identification unit, the supplement identification unit, the message identification unit, and the judgment unit, S110 corresponds to the processing as the supplement identification unit, S120 and S130 correspond to the processing as the message identification unit, and S140 and S150 correspond to the processing as the judgment unit. Padding corresponds to the supplement data, the padding amount corresponds to the data length of the supplement data, the padding information corresponds to the supplement information, and the padding information area 204 corresponds to the supplement information area.

The CAN FD communication frame (i.e., a CAN FD communication frame whose CANID is ID_D) corresponds to the communication frame, the CAN FD data field 103 corresponds to the data field, and the authenticator and MAC correspond to the authentication information. The CANID of the CAN FD communication frame corresponds to the message identifier, the data length indicated by the DLC shown in the DLC field 102 of the CAN FD communication frame corresponds to the specified data length, and the individual message corresponds to the individual message data. The effective message length corresponds to the added value.

4. Other embodiments
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

(4a) In the above-described embodiment, as shown in FIG. 10, in the management ECU 10i_1, the management transmission processing unit 133 may store the padding information at the rear of the authenticator area 203 (i.e., at the very end of the CAN FD data area 103) in S40.

(4b) In the above-described embodiment, as shown in FIG. 11, in the management ECU 10i_1, the management transmission processing unit 133 may store the padding information in an area in front of the authenticator area 203 (i.e., the area between the padding area 202 and the authenticator area 203) in S40.

(4c) In the above-described embodiment, as shown in FIG. 12, in the management ECU 10i_1, the management transmission processing unit 133 may place the padding area 202 in an area in front of the management message area 201 (i.e., after the padding information area 204 located at the beginning) in S40. The padding area 202 may be placed at any position in the CAN FD data area 103.

(4d) In the above-described embodiment, in the communication system 1, for example, the management ECU 10i_1 may include only the management transmission processing unit 133 out of the management reception processing unit 134 and the management transmission processing unit 133, and may not include the management reception processing unit 134. Also, the management ECU 10i_2 may include only the management reception processing unit 134 out of the management reception processing unit 134 and the management transmission processing unit 133, and may not include the management transmission processing unit 133.

(4e) In the above embodiment, in the communication system 1, for example, the management ECU 10i_2 (i.e., the management transmission processing unit 133 provided in the message processing unit 13i) may execute the above-mentioned transmission process. Also, the management ECU 10i_1 (i.e., the management reception processing unit 134 provided in the message processing unit 13i) may execute the above-mentioned reception process. In this case, for example, the management ECU 10i_1 may have only the management reception processing unit 134 out of the management reception processing unit 134 and the management transmission processing unit 133, and may not have the management transmission processing unit 133. Also, the management ECU 10i_2 may have only the management transmission processing unit 133 out of the management reception processing unit 134 and the management transmission processing unit 133, and may not have the management reception processing unit 134. In this case, the management ECU 10i_2 corresponds to the information transmission node, and the management ECU 10i_1 corresponds to the information reception node.

(4f) In the above embodiment, at least one of the normal ECUs 10n may be configured as an ECU that supports both CAN and CAN FD, similar to the management ECU 10i. In other words, the normal ECU 10n may further include a management transmission processing unit 133 and a management reception processing unit 134 in the message processing unit 13n.

(4g) In the above-described embodiment, the communication system 1 is not limited to a system that performs engine control, as described above. The functions of the communication system 1 and each ECU 10 are not limited to the functions described above, and may be various functions for controlling the vehicle.

(4h) The management ECU 10i and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the management ECU 10i and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the management ECU 10i and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by a computer. The method for realizing the functions of each part included in the management ECU 10i does not necessarily need to include software, and all of the functions may be realized using one or more hardware.

(4i) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

(4j) In addition to the above-mentioned management ECU 10i_1 and management ECU 10i_2, the present disclosure can also be realized in various forms, such as a communication system 1 having the management ECU 10i_1 and management ECU 10i_2 as components, a program for causing the management ECU 10i_1 to function, a program for causing the management ECU 10i_2 to function, a non-transitive physical recording medium such as a semiconductor memory on which these programs are recorded, and a communication method.

1... communication system, 10... node, ECU, 10i_1, 10i_2... management ECU, 12i... communication controller, 103... CAN FD data area, 133... management transmission processing unit, 134... management reception processing unit.

Claims (8)

A communication system (1) comprising a plurality of nodes connected to each other, at least one of the nodes being an information transmitting node (10i_1), and at least one of the nodes other than the information transmitting node being an information receiving node (10i_2) communicably connected to the information transmitting node,
The information sending node,
A generating unit (133) configured to generate a communication frame conforming to a predetermined communication protocol;
a transmission unit (12i) configured to transmit the communication frame generated by the generation unit,
The generation unit is
a management unit (S10) configured to generate a management message including at least one individual message data generated by at least one of the plurality of nodes, the individual message data having a data length variable within a predetermined range, and to store the generated management message in a data area of the communication frame;
a supplement execution unit (S20, S30) configured to determine a data length of supplementary data for making the data area (103) equal to a designated data length corresponding to the data length of the management message, and to store the supplementary data of the determined data length in the data area;
a supplementary information section (S40) configured to store supplementary information indicating a data length of the supplementary data at a predetermined position in the data area,
The information receiving node,
A receiving unit (12i) configured to receive the communication frame;
a determination unit (134) configured to determine the data length of the supplementary data in the communication frame received by the receiving unit;
Equipped with
the identification unit includes a supplement identification unit (S110) configured to acquire the supplement information included in the data area of the communication frame and identify the data length of the supplement data based on the supplement information ;
In the information sending node,
the management unit stores the generated management message in the data area of the communication frame to which a predetermined identical message identifier is assigned;
In the information receiving node,
the receiving unit receives the communication frame to which the same message identifier is assigned.
Communication systems. 2. The communication system according to claim 1,
In the information sending node,
The generation unit is
an authentication information unit configured to generate authentication information for detecting tampering of the management message using the management message and to store the generated authentication information in the data area (S50, S60);
Further comprising:
In the information receiving node,
The identification unit is
a message identification unit (S120, S130) configured to calculate the data length of the management message by subtracting the data length of the supplementary data, the data length of the authentication information, and the data length of the supplementary information from the specified data length, and to identify the management message included in the data area using the subtraction value. 3. The communication system according to claim 2,
In the information receiving node,
The identification unit is
a determination unit (S140, S150) configured to generate new authentication information based on the identified management message and an authentication key stored in a key holding unit (14i) provided in the information receiving node, compare the generated new authentication information with the authentication information included in the received communication frame, and determine whether the management message has been tampered with. A communication system according to claim 2 or 3,
In the information sending node,
The supplement execution unit calculates a sum by adding the data length of the management message, the data length of the authentication information, and the data length of the supplementary information, and determines, as the designated data length, a data length that is equal to or greater than the sum and closest to the sum among multiple data length candidate values for the data length of the data area. A communication system according to any one of claims 1 to 4,
The supplemental information section stores the supplemental information at the beginning of the data area. A communication system according to any one of claims 1 to 5 ,
The communication system, wherein the communication protocol is CAN FD. a communication frame that is assigned a predetermined identical message identifier, and an information receiving node that is communicatively connected to an information sending node, the communication frame being provided with a predetermined identical message identifier, the communication frame being provided with a predetermined identical message identifier, the communication frame being provided with a predetermined identical message identifier, the communication frame being provided with a predetermined identical message identifier, and an information sending node that is communicatively connected to an information receiving node, the communication frame being provided with a predetermined identical message identifier, the communication frame being provided with a predetermined identical message identifier, the communication frame being provided with a predetermined identical message identifier , and an information sending node that is communicatively connected to an information sending node,
A generating unit (133) configured to generate the communication frame conforming to the communication protocol;
a transmission unit (12i) configured to transmit the communication frame generated by the generation unit,
The generation unit is
a management unit (S10) configured to generate a management message including at least one individual message data, the individual message data being data generated in at least one of a plurality of nodes including the information receiving node and the information transmitting node, and storing the generated management message in the data area of the communication frame;
a supplement execution unit (S20, S30) configured to determine a data length of the supplement data so as to make the data area (103) equal to a designated data length corresponding to the data length of the management message, and to store the supplement data of the determined data length in the data area;
a supplementary information section (S40) configured to store the supplementary information, which is the supplementary information and indicates the data length of the supplementary data, at a predetermined position in the data area ;
the management unit stores the generated management message in the data area of the communication frame to which the same message identifier is assigned .
Information sending node. The present invention is provided with a generating unit (133) configured to generate a communication frame conforming to a predetermined communication protocol, and a transmitting unit (12i) configured to transmit the communication frame generated by the generating unit, the generating unit generating a management message including at least one individual message data, the individual message data being data generated in at least one of a plurality of nodes and having a data length variable within a predetermined range, a management unit (S10) configured to store the generated management message in a data area of the communication frame, and a data area (103) configured to store the data of the management message. a supplement execution unit (S20, S30) configured to determine a data length of supplementary data to make the data length of the supplementary data equal to a designated data length corresponding to the length of the communication frame, and to store the supplementary data of the determined data length in the data area; and a supplementary information unit (S40) configured to store supplementary information indicating the data length of the supplementary data in a predetermined position in the data area, wherein the management unit comprises an information sending node (10i_1) that stores the generated management message in the data area of the communication frame to which the same predetermined message identifier is assigned , and an information receiving node (10i_2) communicably connected,
the plurality of nodes includes the information receiving node and the information transmitting node,
A receiving unit (12i) configured to receive the communication frame;
a determination unit (134) configured to determine the data length of the supplementary data in the communication frame received by the receiving unit;
Equipped with
the identification unit includes a supplement identification unit (S110) configured to acquire the supplement information included in the data area of the communication frame and identify the data length of the supplement data based on the supplement information ;
the receiving unit receives the communication frame to which the same message identifier is assigned .
Information receiving node.

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