JP2017118317A - Communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device that transmits and receives frames via a communication line and can secure a lot of type areas while preventing data transmission efficiency from deteriorating.SOLUTION: In a communication system 1, ECUs 20, 30, 40 comprise a frame generation unit 23 and a transmission unit 24. The frame generation unit 23 generates a frame including a type area representing a type of data and a data length area indicating length of the data, and making at least part of the data length area into part of the type area. Then, the transmission unit 24 transmits the frame generated by the frame generation unit 23 onto a communication line 5.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a communication device that transmits and receives a frame via a communication line.

  In Patent Literature 1, as the communication device, a data length area in which information indicating a data length is stored in a frame including actual data representing substantial data to be transmitted and received is stored. It is also used in the area. In this configuration, since the actual data can be sent using a part of the data length area, the communication efficiency of the actual data can be improved.

JP 2014-204287 A

  By the way, some of the communication apparatuses as described above have a type area indicating a data type in a part of a frame. There is a request to secure a lot of areas as type areas and identify more types of data, but there is a problem that the communication efficiency of actual data decreases if many areas are secured as type areas. is there.

  In one aspect of the present disclosure, it is desirable that a communication apparatus that transmits and receives a frame via a communication line can secure a large number of classification areas while suppressing a decrease in data transmission efficiency.

The communication device according to one aspect of the present disclosure includes a frame generation unit (23) and a transmission unit (24).
The frame generation unit is a frame (60) including a type area (62) indicating the type of data and a data length area (66) indicating the length of the data, and at least a part of the data length area is typed Generate a frame that is part of the region. Then, the transmission unit transmits the frame generated by the frame generation unit on the communication line.

  In addition, the communication device according to one aspect of the present disclosure includes a reception unit (26) and a data recognition unit (27). The receiving unit receives a frame including a type area indicating the type of data and a data length area indicating the length of the data, wherein at least a part of the data length area is a part of the type area. . Further, the data recognition unit extracts the type area and the data length area from the received frame, and recognizes the type of data based on the data included in the type area and the data length area.

  According to such communication apparatuses, since at least a part of the data length area is used as a part of the type area, it is possible to secure a large number of type areas while suppressing a decrease in data transmission efficiency. Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiment described later as one aspect, and the technical scope of the present disclosure It is not limited.

It is a block diagram which shows the structure of a communication system. It is explanatory drawing which shows the structural example of a communication frame. It is an example of a data setting at the time of using DLC for a destination. It is an example of a data setting when DLC cannot be used. It is a flowchart which shows the reception process which the data recognition part of ECU performs.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
A communication system 1 shown in FIG. 1 is mounted on a vehicle such as a passenger car, for example, and includes a tester 10 and a plurality of ECUs 20, 30, 35, 36, 37, and 40. The tester 10 has a function of designating one or a plurality of ECUs 20, 30, 35, 36, 37, and 40, requesting data from the designated ECU, and rewriting a program in the designated ECU. In addition, the tester 10 is configured to be detachable from the communication line 5 and performs communication via the communication line 5 when connected to the communication line 5.

  The ECUs 20 and 40 of the plurality of ECUs are connected to the communication line 5, and the ECUs 35, 36, and 37 of the plurality of ECUs are connected to a communication line 6 different from the communication line 5. The ECU 30 is connected to both the communication lines 5 and 6 and functions as a relay device that relays data between the communication lines 5 and 6.

  The tester 10 and the ECUs 20, 30, and 40 communicate with each other through a communication line 5 using a CAN (Controller Area Network: registered trademark) protocol. In addition, the ECUs 30, 35, 36, and 37 communicate with each other by the LIN (Local Interconnect Network) protocol via the communication line 6.

  Each ECU 20, 30, 35, 36, 37, 40 has a function as a well-known electronic control device preset for each ECU. For example, it individually has a function of controlling components mounted on a vehicle such as an engine, a brake, an air conditioner, and a car navigation system.

  Below, the function regarding the communication about the tester 10 and several ECU20,30,35,36,37,40 is demonstrated. Note that the ECUs 35, 36, and 37 connected to the communication line 6 have a well-known configuration for performing communication by LIN, and thus the description thereof is omitted, and the ECUs 20, 30, and 40 connected to the communication line 5 and the communication are omitted. The tester 10 that can be connected to the line 5 will be described. However, since the tester 10 and the ECUs 20, 30, and 40 have the same communication functions, the ECU 20 will be described as a representative of them.

  The ECU 20 is mainly configured by a known microcomputer having a CPU 21 and a semiconductor memory (hereinafter, memory 22) such as a RAM, a ROM, and a flash memory. Various functions of the ECU 20 are realized by the CPU 21 executing a program stored in a non-transitional physical recording medium. In this example, the memory 22 corresponds to a non-transitional tangible recording medium that stores a program. Further, by executing this program, a method corresponding to the program is executed. The number of microcomputers constituting the ECU 20 may be one or plural.

  ECU20 is provided with the flame | frame production | generation part 23, the transmission part 24, the receiving part 26, and the data recognition part 27 as a structure of the function implement | achieved when CPU21 runs a program, as shown in FIG. The method of realizing these elements constituting the ECU 20 is not limited to software, and some or all of the elements may be realized using hardware that combines a logic circuit, an analog circuit, and the like.

[1-2. processing]
The frame generation unit 23 generates a data frame 60 for data to be transmitted, such as when an event occurs in the ECU 20, and sends the data frame 60 to the transmission unit 24. The data frame 60 represents all the data to be transmitted and received, and the data frame 60 includes an ID 62, a control field 64, and a data field 68 as shown in FIG.

  As the ID 62, for example, an 11-bit area is prepared, and information indicating the type of data is stored. An 8-bit area is prepared for the control field 64, and a DLC (Data Length Code) 66 indicating the data length is assigned to the lower 4 bits of the area. The data length indicates the size of data transmitted in a frame. In the DLC 66, the data length of the data field 68 is expressed by the number of bytes using 0-8 out of the numbers 0-15 that can be expressed by 4 bits.

  That is, for example, if the bit value in the DLC 66 is 1, the data field 68 has a data length of 1 byte, and if the bit value in the DLC 66 is 8, for example, it indicates that the data field 68 has a data length of 8 bytes.

  The data field 68 is an area in which actual data excluding the header portion and footer portion of the frame is stored. The actual data represents substantial data to be transmitted / received. For example, a state value such as a sensor value, a command value indicating a command for rewriting a program, a rewriting program itself, and the like are included.

  Here, the DLC 66 is set to have an invalid area where the data value is invalid when the data length is a specific value. That is, when the bit value in the DLC 66 is 8-15, in other words, when d3 that is the most significant bit among the 4 bits indicating the DLC 66 is 1, the data length is 8 bytes only with this bit value. Therefore, d2, d1, and d0, which are the lower 3 bits of the 4 bits indicating DLC 66, are meaningless in indicating the data length. That is, the lower 3 bits are an invalid area.

  Therefore, when the data length of the data field 68 is 8 bytes and the DLC 66 has an invalid area, the frame generation unit 23 converts the lower 3 bits, which are at least part of the DLC 66, into the area indicating the data type (that is, the CANID). A data frame 60 as a part of the area shown in FIG. That is, the type of data is expressed using a 14-bit area of 11 bits of ID62 and lower 3 bits of DLC66.

  In the communication system 1, data expressing the data type using only the 11-bit area of ID 62 (hereinafter, data of the type belonging to the data group A) and data using the 14-bit area of ID 62 and DLC 66 are used. Can be generated (hereinafter, data of a type belonging to the data group B).

  When the data type belongs to the data group A, the frame generation unit 23 sets an arbitrary DLC 66 value according to the size of the actual data to be transmitted. That is, the data length of the data field 68 can be set to 0-8. On the other hand, when the data type belongs to the data group B, the frame generation unit 23 sets the value of the DLC 66 to 8 regardless of the size of the actual data to be transmitted. Then, the upper 11 bits of the data indicating the data type are stored in the area of ID 62, and the lower 3 bits are stored in the lower 3 bits of DLC 66.

  In particular, the lower 3 bits in the DLC 66 area can be used as an area to specify the destination. For example, as shown in FIG. 3, in the area of ID 62, information indicating the same data type “0x1F1” is stored, and different values are stored in the lower 3 bits of DLC 66 according to the destination ECU. Specifically, if the destination is ECU [B-1] 35, “0x1” is stored. If the destination is ECU [B-2] 36, “0x2” is stored, and the destination is ECU [B −3] If “38”, “0x3” is stored.

  In the conventional configuration, as shown in FIG. 4, since it is necessary to include the data type and the destination in the area of ID62, if there are three destinations, for example, “0x1F1” “0x1F2” in the area of ID62 Three IDs of “0x1F3” were required. However, in the communication system 1 of this embodiment, since the destination is expressed by the lower 3 bits of the DLC 66, only one ID can be required in the area of ID62. In this way, the data frame 60 is generated by the frame generation unit 23.

  The transmission unit 24 transmits the data frame 60 generated by the frame generation unit 23 on the communication line. In addition, the receiving unit 26 receives the data frame 60 and sends it to the data recognition unit 27. The transmission unit 24 and the reception unit 26 can have a known configuration.

  The data recognizing unit 27 extracts the ID 62 and the DLC 66 from the data frame 60 received by the receiving unit 26, and recognizes the type of data based on the data included in the ID 62 and the DLC 66. When the DLC 66 of the received data has an invalid area, that is, when the most significant bit of the DLC 66 is 1, the data type is recognized based on the data included in the ID 62 and the lower 3 bits of the DLC 66.

  Here, the reception process executed in the data recognition unit 27 will be described with reference to the flowchart shown in FIG. The reception process is a process for recognizing the data type included in the data frame 60. The reception process is executed every time data is sent from the reception unit 26.

  In the reception process, as shown in FIG. 5, it is determined in S110 whether the value of the DLC66 area is 9 or more. If the value of the DLC 66 area is 8 or less, in S120, the data type is recognized as a normal CAN ID, and the recognized value is notified. The notification target is, for example, a part in the ECU 20 having a function of recognizing the type of data and the actual data.

  Note that the process of recognizing the data type as a normal CAN ID represents a process executed in a known CAN that does not include the DLC 66 area and recognizes the data type with only 11 bits of ID62.

If the value of the DLC66 area is 9 or more at S110, the lower 3 bits of the DLC66 area are extracted at S130. Here, the lower 3 bits are CANIDβ.
Subsequently, in S140, the value included in the ID62 area is set as CANIDα, and CANIDα and CANIDβ are combined, and the obtained value is set as CANIDγ. In S150, CANIDγ is notified as a value representing the data type.

  When such processing ends, the reception processing ends. Note that CANIDγ has only the data amount changed from 11 bits to 14 bits, and the data type has not been changed. Therefore, in this processing, general CAN software can be used without modification.

[1-3. effect]
According to the first embodiment described in detail above, the following effects can be obtained.
(1a) In the ECUs 20, 30, and 40 of the communication system 1, the frame generation unit 23 is a data frame 60 that includes an ID 62 that indicates the type of data and a DLC 66 that indicates the length of the data. A data frame 60 is generated in which at least a part is a part of an area representing the data type. Then, the transmission unit 24 transmits the data frame 60 generated by the frame generation unit 23 on the communication line.

  In the ECUs 20, 30, and 40 of the communication system 1, the receiving unit 26 is a data frame 60 including an ID 62 and a DLC 66, and at least a part of the DLC 66 is a part of an area representing a data type. The received data frame 60 is received. Further, the data recognition unit 27 extracts the ID 62 and the DLC 66 from the received data frame 60 and recognizes the data type based on the data included in the ID 62 and the DLC 66.

  According to such a communication system 1, since at least a part of the DLC 66 is used as a part of the area representing the data type, a large number of IDs 62 can be secured while suppressing a decrease in data transmission efficiency. Further, even when compared with a configuration in which a part of the data field 68 is an area representing a data type, it is possible to suppress a decrease in data transmission efficiency.

  Further, according to the communication system 1 as described above, even if the data frame 60 transmitted from another ECU includes data indicating the data type in the DLC 66, it can be recognized well.

  (1b) In the communication system 1 described above, the DLC 66 is set to have an invalid area where the data value becomes invalid when the data length is a specific value. Then, when the DLC 66 has an invalid area, the frame generation unit 23 generates data in which at least a part of the DLC 66 is a part of the ID 62. In addition, when the data recognition unit 27 has an invalid area in the DLC 66 of the received data, the data recognition unit 27 recognizes the type of data based on the data included in the ID 62 and the invalid area. Note that “invalid” indicates that a bit value in a specific bit has no meaning in the process of reading data. The data value indicates one or a plurality of bit values.

  According to such a communication system 1, since the invalid area in the DLC 66 is used as a part of the area representing the data type, the area representing the data type can be expanded without affecting the identification of the data length by the DLC 66. Can do.

(1c) In the communication system 1 described above, communication is performed using the CAN protocol, and a 4-bit DLC area is set as the DLC 66.
According to the communication system 1 as described above, since the DLC area in the CAN is used, it is possible to secure a large number of IDs while reliably suppressing a decrease in data transmission efficiency.

(1d) In the communication system 1 described above, the lower 3 bits in the DLC area are set as part of the area representing the data type.
According to such a communication system 1, since the lower 3 bits of the DLC, which is invalid when the data length is 8 bytes, is used as the ID 62, compared with the configuration using the lower 1 bit or 2 bits of the DLC, Areas representing more data types can be secured.

(1e) In the communication system 1 described above, the lower 3 bits in the DLC area are also used as an area for specifying the destination.
According to such a communication system 1, it is possible to associate more destinations even when information specifying the destination is included in the area representing the data type.

  This is particularly effective when it is desired to use more combinations of data types and destinations, such as a configuration in which an external device such as the tester 10 can be connected. For example, in the above embodiment, when the ECU 30 receives certain data via the CAN communication line 5 and relays this data to the LIN communication line 6, one specific CANID is assigned as a message. By assigning the CANID of the LIN frame relayed by the ECU 30 to the LIN bus to the lower 3 bits of the DLC area and transmitting the CANID, the exhaustion of the ID62 area can be suppressed.

  In the diagnostic communication using the tester 10, the CANID that can be used is determined in the standard as the 7xx series. For this reason, depletion of CANID used for diagnostic communication is more realistic due to the recent increase in the number of ECUs. In the diagnostic communication, there is a specification in which CANID is used as a functional address, and actions are taken simultaneously when a plurality of ECUs having the same address as medical examination targets receive functional addresses. In many cases, in this specification, there are a plurality of function addresses such as all ECU designation IDs to which all ECUs react, and group designation IDs to which a plurality of predetermined ECUs react to one ID. Are allocated and operated.

  Even in such a case, if the configuration of the above-described embodiment is used, a group (all ECUs, a specific group) can be specified by the lower 3 bits of the DLC, and the assignment as a function address can be done by one CANID.

[2. Other Embodiments]
As mentioned above, although the form for implementing this indication was demonstrated, this indication is not limited to the above-mentioned embodiment, and can carry out various modifications.

  (2a) In the above embodiment, a case has been described in which a part of the DLC 66 is a part of the area representing the data type. That is, when one or more predetermined bit values in the DLC 66 are predetermined values, the other bits in the DLC 66 are used as a part of the area indicating the data type. However, the entire DLC 66 may be part of the area representing the data type. In this case, a data length fixed in advance may be used.

  (2b) The functions of one constituent element in the above embodiment may be distributed as a plurality of constituent elements, or the functions of a plurality of constituent elements may be integrated into one constituent element. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claims are embodiments of the present disclosure.

  (2c) In addition to the communication system 1 described above, non-transitional actual recording such as a device that is a component of the communication system 1, a program for causing a computer to function as the communication system 1, and a semiconductor memory that records the program The present disclosure can also be realized in various forms such as a medium and a communication method.

  DESCRIPTION OF SYMBOLS 1 ... Communication system 5,6 ... Communication line, 10 ... Tester, 20, 30, 35, 36, 37, 40 ... ECU, 21 ... CPU, 22 ... Memory, 23 ... Frame generation part, 24 ... Transmission part, 26 ... receiving part, 27 ... data recognition part, 60 ... data frame, 64 ... control field, 68 ... data field.

Claims (7)

A communication device (20, 30, 40) for transmitting and receiving a frame (60) via a communication line,
A frame including a type area (62) indicating the type of data and a data length area (66) indicating the length of the data, wherein at least a part of the data length area is a part of the type area A frame generation unit (23) for generating a frame;
A transmission unit (24) for transmitting the frame generated by the frame generation unit on the communication line;
A communication device comprising: The communication device according to claim 1,
A receiving unit (26) for receiving a frame transmitted from another communication device;
A data recognition unit (27) that extracts the type area and the data length area from the received frame and recognizes the type of data based on data included in the type area and the data length area;
A communication device further comprising: The communication device according to claim 2,
The data length area is set to have an invalid area where the data value is invalid when the data length is a specific value,
The frame generation unit generates data having at least a part of the data length area as a part of the type area when the invalid area is included in the data length area,
The data recognition unit is a communication device that recognizes the type of data based on the type area and the data included in the invalid area when the invalid area is included in the data length area of the received data. The communication device according to any one of claims 1 to 3,
The communication device communicates with a CAN (Controller Area Network) protocol,
A communication device in which a 4-bit DLC (Data Length Code) area is set as the data length area. The communication device according to claim 4,
A communication apparatus in which the lower 3 bits in the DLC area are set as part of the type area. The communication device according to claim 4 or 5, wherein
The lower 3 bits in the DLC area are used as an area for specifying a partner. A receiving unit that receives a frame that includes a type area that indicates a type of data and a data length area that indicates the length of data, and at least a part of the data length area is part of the type area (26) and
A data recognition unit (27) for extracting the type area and the data length area from the received frame and recognizing the type of data based on data included in the type area and the data length area;
A communication device comprising: