JP2014027406A - Relay device, relay system, and relay method of can data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relay device which can improve throughput in wireless communication and ensure real time performance when CAN data communicated between CAN nodes is relayed via a wireless network.SOLUTION: A relay device 21 (23) is provided corresponding to each of CAN node 11 (13) to be a transmission source and CAN node 13 (11) to be a reception destination and relays CAN data communicated between the CAN nodes 11, 13 via a wireless network 10 constructed with the other relay device 23 (21). The relay device 21 (23) stores the CAN data to be wirelessly transmitted of received CAN data in a buffer, and at a predetermined wireless transmission timing of the relay device 21 (23): transmits, when the CAN data stored in the buffer is single data, the single CAN data to the other relay device 23 (21); and aggregates, when a plurality of CAN data are stored in the buffer, the plurality of CAN data for collectively transmitting to the other relay device 23 (21).

Description

  The present invention relates to a CAN data relay apparatus, relay system, and relay method for relaying CAN data communicated between CAN nodes via a wireless network.

  A CAN (Controller Area Network) is used in control of automobiles, FA (Factory Automation), medical equipment, machine tools, and the like. The CAN is a network that connects a controller such as an EUC (electronic control unit) and each device in a communicable manner, and transmits state information of each device to the controller and a control command to each device. Used for Controllers and devices connected to the CAN are called CAN nodes. The CAN data communicated between the CAN nodes is data indicating the device state, the control command, and the like. As shown in FIG. 4, the standard format (data frame) of CAN data stores the data contents and information for identifying the transmission source node in the ID field, and the length of the data to be communicated is the control field. Data of 1 to 8 bytes that is stored in DLC (data length code) and is a communication target is stored in the data field portion. In CAN, all CAN nodes share one transmission path, and the transmission of CAN data is not controlled, and broadcast in which CAN data is transmitted to all CAN nodes is premised on communication.

  However, when changing the arrangement of CAN nodes such as controllers and devices, each CAN node is usually connected by a wired dedicated line. Therefore, it becomes necessary to replace the cable for exclusive use of the cable, which requires labor and cost.

  As one effective means for solving this problem, it is conceivable to provide each CAN node with a relay device that relays CAN data communicated between CAN nodes via a wireless network. In this case, the relay device may be configured to perform wireless communication complying with the wireless LAN communication standard IEEE802.11.

  In addition, although patent document 1 is not directly related to the said relay apparatus, there exists a suggestion of performing conversion with a radio | wireless communication protocol and a CAN protocol.

Japanese Patent No. 3754456

  However, wireless communication requires a handshake protocol that is an agreement prior to the start of communication as compared to wired communication. If the communication speed is increased, the overhead of the handshake protocol becomes significant and the throughput decreases. In particular, the CAN data has a maximum of 8 bytes and is extremely small compared to a general Ethernet (registered trademark) packet size (for example, about 64 bytes to 1500 bytes) handled in a wireless LAN. The problem is that the throughput decreases due to an increase in overhead of the handshake protocol.

  As one effective means for improving the throughput, CAN data to be transmitted wirelessly is stored in a buffer, and when a certain amount of data is accumulated, a plurality of stored CAN data is aggregated (integrated) and wirelessly transmitted. It is possible to send all at once. However, although this means improves the throughput, it accumulates CAN data, so the real-time property is impaired. As described above, since CAN is used for device control, it is necessary to appropriately ensure real-time performance.

  The present invention has been made paying attention to such problems, and its purpose is to improve wireless communication throughput and real-time performance when relaying CAN data communicated between CAN nodes via a wireless network. It is to provide a relay device, a relay system, and a relay method that satisfy both of the requirements.

  In order to achieve the object, the present invention takes the following means.

That is, the CAN data relay device of the present invention is
A CAN communication unit that communicates CAN data with a CAN node via a wire, a wireless communication unit that wirelessly communicates with another relay device at a predetermined wireless transmission timing, and a source via the CAN communication unit or the wireless communication unit CAN data transmitted from the CAN node to be received, relay control unit that relays the received CAN data to the CAN node that is the reception destination via the CAN communication unit or the wireless communication unit, and stores the CAN data And a buffer for
The relay control unit stores CAN data to be transmitted wirelessly in the received CAN data in the buffer, and when the CAN data stored in the buffer at the wireless transmission timing is single, When a plurality of CAN data accumulated in the buffer exists at the wireless transmission timing while a single CAN data is transmitted to another relay device, the plurality of CAN data are aggregated to another relay device. The apparatus is characterized in that it is configured to collectively transmit to the apparatus.

  According to this configuration, in a state where the CAN data to be transmitted wirelessly is accumulated in the buffer, the CAN data is always transmitted at the wireless communication timing. Therefore, there is no waiting until the CAN data becomes plural. Therefore, it is possible to ensure the real-time property required for CAN communication, as compared with the case of waiting for a plurality of CAN data despite the wireless communication timing. Nevertheless, when a plurality of CAN data to be transmitted wirelessly are accumulated in the buffer, the plurality of CAN data are aggregated and wirelessly transmitted collectively, thereby improving the throughput. Therefore, it is possible to achieve both improvement in the throughput of wireless communication and securing real-time performance.

  In order to ensure compatibility accurately, it is effective that the wireless communication unit is configured to perform wireless communication conforming to the IEEE802.11 standard for wireless LAN communication.

  In order to improve communication quality, the master relay device is determined when one of the relay devices belonging to the wireless network is a master relay device and the other relay device is a slave relay device. The master relay device and the slave relay device can communicate with each other only at the wireless transmission timing, and QoS (Quality) that guarantees wireless communication between the relay devices by sequentially switching the slave relay device that is the communication partner of the master relay device. of Service) control is preferably implemented.

  In order to improve throughput, the master relay device stores in advance association information between a CAN node and a relay device connected to the CAN node by wire, and the CAN data accumulated in the buffer is It is desirable to be configured to transmit wirelessly only to the relay device associated with the CAN node that is the CAN data receiving destination.

  In order to ensure the compatibility accurately, it is configured to perform QoS control using HCCA (Hybrid coordination function Controlled Channel Access) defined in the wireless LAN communication standard IEEE802.11e. It is effective.

The present invention can be specified as a CAN data relay system. That is, the CAN data relay system of the present invention includes a relay device corresponding to a CAN node as a transmission source and a relay device corresponding to a CAN node as a reception destination, and CAN data communicated between CAN nodes, A system for relaying via a wireless network constructed by both relay devices,
Each relay device
A CAN communication unit that communicates CAN data with a CAN node via a wire;
A wireless communication unit that wirelessly communicates with another relay device at a predetermined wireless transmission timing;
The CAN communication unit or the wireless communication unit receives CAN data transmitted from a CAN node as a transmission source via the CAN communication unit or the wireless communication unit, and sends the received CAN data to the CAN node as a reception destination. A relay control unit that relays via
A buffer for storing CAN data,
The relay control unit stores CAN data to be transmitted wirelessly in the received CAN data in the buffer, and when the CAN data stored in the buffer at the wireless transmission timing is single, When a plurality of CAN data accumulated in the buffer exists at the wireless transmission timing while a single CAN data is transmitted to another relay device, the plurality of CAN data are aggregated to another relay device. The apparatus is characterized in that it is configured to collectively transmit to the apparatus.

The present invention can be specified as a CAN data relay method. That is, in a system including a relay device corresponding to a CAN node as a transmission source and a relay device corresponding to a CAN node as a reception destination, the CAN data communicated between the CAN nodes is wirelessly constructed by both relay devices. A method of relaying through a network,
Of the CAN data received from the CAN node or the relay device, CAN data to be transmitted wirelessly is stored in a buffer, and when the CAN data stored in the buffer is single at a predetermined wireless transmission timing, When one piece of CAN data is transmitted wirelessly and there are a plurality of pieces of CAN data accumulated in the buffer at the wireless transmission timing, the plurality of pieces of CAN data are aggregated and wirelessly transmitted collectively. Features.

  Since the present invention has the configuration described above, the CAN data to be transmitted wirelessly is always transmitted at the wireless communication timing, and since there is no waiting until the CAN data becomes plural, real-time performance can be ensured. . In addition, when there are a plurality of CAN data to be transmitted wirelessly, the plurality of CAN data are aggregated and transmitted in a batch, thereby improving the throughput. Therefore, it is possible to provide a CAN data relay device, relay system, and relay method that can improve both the throughput of wireless communication and secure real-time performance.

The schematic block diagram of the relay system which has a CAN node and a relay apparatus. The block diagram which shows the structure of a relay apparatus typically. The figure which shows the buffer which memorize | stores CAN data. The figure which shows the format of a CAN data frame typically. The figure which shows the format of a radio | wireless data frame typically. Explanatory drawing regarding the prior operation | movement of QoS control in radio | wireless communication. Explanatory drawing regarding the operation | movement of QoS control in radio | wireless communication. The figure which shows the flow of CAN data over the whole system. Explanatory drawing which shows typically a mode that an MPDU payload is produced | generated from single CAN data. Explanatory drawing which shows a mode that an MPDU payload is produced | generated from several CAN data. The flowchart which shows the CAN reception process routine which a master relay apparatus performs. The flowchart which shows the CAN data radio | wireless transmission processing routine which a master relay apparatus performs. The flowchart which shows the CAN data radio | wireless reception process routine which a master relay apparatus performs. The flowchart which shows the CAN reception process routine which a slave relay apparatus performs. The flowchart which shows the CAN data radio | wireless transmission processing routine which a slave relay apparatus performs. The flowchart which shows the CAN data radio | wireless reception process routine which a slave relay apparatus performs. Explanatory drawing which shows the association information which the master relay apparatus which concerns on other embodiment has. Explanatory drawing which shows the association information which the master relay apparatus which concerns on other embodiment has.

  Hereinafter, a relay device and a relay system according to an embodiment of the present invention will be described with reference to the drawings.

<Overall configuration of relay system>
FIG. 1 is a diagram illustrating an example of a machine tool to which the relay device and the relay system of the present embodiment are applied. As shown in FIG. 1, the machine tool includes a first peripheral device 11 that can also be called a first CAN (Controller Area Network) node 11, a second peripheral device 12 that can also be called a second CAN node 12, And a controller 13 that can also be called a third CAN node 13 that controls the second peripheral devices 11 and 12. Corresponding first, second, and third relay devices 21, 22, and 23 are provided in the first and second peripheral devices 11 and 12 and the controller 13, respectively. Each of the relay devices 21, 22, and 23 is connected to the corresponding CAN node and CAN data so that they can communicate with each other by wire, and the wireless network 10 is constructed with other relay devices. As shown by an imaginary line 14 in the figure, the relay devices 21, 22, and 23 relay, for example, CAN data communicated between the CAN nodes 11, 12, and 13 via the wireless network 10. In other words, the machine tool includes a relay device (21) corresponding to the CAN node (11) serving as a transmission source and a relay device (23) corresponding to the CAN node (13) serving as a reception destination. It has a system that relays CAN data communicated by (11, 13) via a wireless network 10 constructed by relay devices (21, 23).

  As illustrated in FIG. 1, one relay device (third relay device 23) among a plurality of relay devices 21, 22, and 23 belonging to the wireless network 10 is a master relay device 23 that is an access point, and the other relay devices. The (first and second relay devices 21 and 22) are slave relay devices. When each relay device 21, 22, and 23 performs communication at individual timings conforming to CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) defined in the wireless LAN communication standard IEEE802.11, reliable wireless communication is achieved. Communication cannot be guaranteed. Therefore, the master relay device 23 and the slave relay devices 21 and 22 can communicate with each other only at a predetermined wireless transmission timing determined by the master relay device 23, and the slave relay devices 21 and 22 as communication partners of the master relay device 23 are sequentially connected. By switching, QoS (Quality of Service) control for guaranteeing wireless communication between the relay apparatuses 21, 22, and 23 is executed. In this embodiment, HCCA (Hybrid coordination function Controlled Channel Access) defined in IEEE802.11e is used as the QoS.

<Configuration of relay device>
As shown in FIG. 2, the relay device 21 (22, 23) is connected to the CAN communication unit 30 that communicates CAN data with the CAN node 11 (12, 13) via a wire, and another relay at a predetermined wireless transmission timing. The wireless communication unit 31 wirelessly communicates with the apparatus, a relay control unit 32a that controls relay of CAN data, and a buffer 33a that stores CAN data to be transmitted wirelessly. Since the predetermined wireless communication timing by the wireless communication unit 31 and the predetermined transmission timing by the CAN communication unit 30 are independent from each other, both timings are different.

  Specifically, each of these units 30, 31, 32a, 33a is realized by the following configuration. That is, as shown in FIG. 2, the relay devices 21, 22, and 23 include a CPU (Celtral Processing Unit) 32, an instruction memory 34, a data memory 33, a wireless communication unit 31, a boot ROM (Read Only Memory) 35, and a serial flash It has an SPI (Serial Peripheral Interface) 36 to which a memory is connected, a GPIO (General Purpose Input / Output) 37 that functions as an input / output port, and a CAN communication unit 30. These units 30 to 37 are connected via a bus switch 38. The CPU 32 executes the control program stored in the instruction memory 34, thereby realizing the relay control unit 32a that controls the operation of the relay device in cooperation with peripheral hardware resources. The CPU 32 of the master relay device 23 executes a CAN reception processing routine shown in FIG. 10, a CAN data wireless transmission processing routine shown in FIG. 11, and a CAN data wireless reception processing routine shown in FIG. The CPU 32 of the slave relay apparatuses 21 and 22 executes a CAN reception processing routine shown in FIG. 13, a CAN data wireless transmission processing routine shown in FIG. 14, and a CAN data wireless reception processing routine shown in FIG.

  As shown in FIG. 2, the boot ROM 35 stores a program for expanding a program from a serial flash memory to a data memory via the GPIO 37 when the apparatus is started. The radio communication unit 31 includes an RF (Radio Frequency) 31a connected to an antenna, an ADC (Analog Digital Converter) 31b that performs analog / digital conversion of signals between the RF 31a, a DAC (Digital Analog Converter) 31c, CAN data, It has an IEEE802.11 MAC (Media Access Control) 31 d that performs conversion processing with a radio frame (IEEE802.11 frame), and is connected to the bus switch 38 via a DMA (Direct Memory Access) 39.

  The data memory 33 stores data updated and referred to by the CPU 32. The data memory 33 has a buffer 33a for storing CAN data to be transmitted wirelessly. The buffer 33a is a buffer managed for each CAN ID. As shown in FIG. 3, the buffer 33a of the master relay device 23 is a command buffer for storing CAN data to be transmitted from the controller to each device, and for transferring CAN data received from a certain device to another device. Device information buffer. As shown in FIG. 3, each buffer stores an ID extracted from the CAN data shown in FIG. 4, a data length code (DLC) of the control field, and data of the data field.

<Explanation of CAN data>
CAN data communicated between CAN nodes will be described. FIG. 4 shows a data frame format defined by CAN. The details of the CAN data frame will be described only for the parts related to the present invention. The CAN data frame mainly includes an ID field, a control field DLC (data length code), and a data field. The ID field is used to identify the content of data. The data field part stores data to be transmitted. DLC indicates the length of data stored in the data field portion.

<Description of wireless data>
Wireless data communicated between relay devices will be described. FIG. 5 shows an IEEE 802.11 frame format defined by the wireless LAN communication standard IEEE 802.11. Details of the IEEE802.11 frame will be described only for the parts related to the present invention. The IEEE802.11 frame is composed of a PLCP preamble which is a bit string of a synchronization signal, a PLCP header having information such as a modulation method (transmission speed) and data length, a PSDU composed of an IEEE802.11 header and actual data. . PSDU is called MPDU which is a transmission unit in MAC (Media Access Control) layer, IEEE802.11 header is called MPDU header, and Frame Body is called MPDU payload.

  As shown in FIG. 5, the IEEE802.11 header includes a Frame Control field, a Duration / ID field having information such as a time required for frame transmission, information such as a destination, a transmission source, and an access point MAC address (ESSID). Adress 1, 2, 3, and 4 fields, and a Sequence Control field having information such as a sequence number of data to be transmitted.

  In particular, the Frame Control field includes information such as the type of frame, the destination of the frame, whether the transmission source is wireless or wired, and fragment information. Specifically, the Frame Control field has a Protocol Version field, a Type field, a Subtype field, and the like. The Type field and Subtype field are used in the QoS (Quality of Service) control.

<Operation of QoS control>
The operation of QoS control will be described. First, the preliminary operation shown in FIG. 6 is performed. That is, Beacon is transmitted from the master relay device 23 wirelessly. This Beacon is a signal notifying that the slave relay apparatuses 21 and 22 need to be accepted in order to belong to the wireless network. Upon receiving the Beacon, the slave relay devices 21 and 22 send out an Auth Request requesting authentication, and the master relay device 23 sends out an Auth Response that approves the authentication. When the authentication is approved, the slave relay devices 21 and 22 send an Association-Request requesting connection, and the master relay device 23 sends an Association-Response permitting the connection request. When the connection request is permitted, the slave relay devices 21 and 22 send out ADTS-Request for requesting the start of communication using a predetermined TSPEC (Traffic SPECification) parameter, and the master relay device 23 notifies the result. Send ADTS-Response. TSPEC is a parameter set in advance according to the nature of data to be communicated and the required transmission conditions.

  The preliminary operation shown in FIG. 6 is performed. As shown in FIG. 7, in the state where each slave relay device 21, 22 is connected to the wireless network centering on the master relay device 23, the master relay device 23 Based on the TSPEC parameters received from the slave relay apparatuses 21 and 22, radio transmission timings at which the slave relay apparatuses 21 and 22 can perform radio transmission are assigned. In the example illustrated in FIG. 7, first, the wireless transmission timing TD1 is assigned to the first relay device 21, and then the wireless transmission timing TD2 is assigned to the second relay device 22. The master relay device 23 gives transmission rights to the slave relay devices 21 and 22 by repeatedly transmitting the QoS CF-Poll frame according to the assigned wireless transmission timing. The QoS CF-Poll frame describes a transmission permission time (TXOP), and the slave relay apparatuses 21 and 22 can transmit data within the transmission permission time. The “QoS Data + CF-Poll” frame is a frame for transmitting a transmission right together with the CAN data to the slave relay apparatuses 21 and 22, and the “QoS + CF-Poll” frame is a transmission right to the slave relay apparatuses 21 and 22. It is a frame to be transmitted. The “QoS Data” frame is a frame in which the slave relay apparatuses 21 and 22 transmit CAN data. “CF-Ack” is an Ack for the previous frame. “QoS Data + CF-Ack” is a frame for transmitting CAN data together with Ack for the previous frame. Which of these types the frame is identified by the Type field and Subtype field in the Frame Control field.

<Flow of CAN data>
The flow of CAN data will be described. In this example, as shown in FIG. 8, CAN data (ID = 1) indicating a control command to the first CAN node 11 is sent from the third CAN node 13 (controller 13), and the first An example in which CAN data (ID = 1) indicating device status data is transmitted from the CAN node 11 will be described. For convenience of explanation, ID = 1 is a control command to the first CAN node or device information of the first CAN node, and ID = 2 is a control command to the second CAN node or the second CAN node. Device information.

  Each relay device 21, 22, 23 transmits / receives CAN data to / from wired CAN nodes 11, 12, 13 at a transmission timing defined by CAN. As shown in the period TM1 in FIG. 8, the master relay device 23 (third relay device 23) controls the control command CAN data from the controller 13 (third CAN node 13) at CAN transmission timing (for example, every time T1). (ID = 1) is received (see steps S101 and S102 in FIG. 10). Since the received control command CAN data is CAN data to be transmitted wirelessly to the other CAN nodes 11 and 12, it is stored in the area of ID = 1 in the command buffer shown in FIG. (See S103). Similarly, as shown in the period TM1 of FIG. 8, the first relay device 21 receives the device state CAN data (ID = 1) from the first peripheral device 11 (first CAN node 11) (FIG. 8). 13 processes S401 and S402). Since the received device information CAN data is CAN data to be transmitted wirelessly to the other CAN nodes 12 and 13, it is stored in a buffer (see process S403 in FIG. 13). That is, the relay control unit 32a shown in FIG. 2 receives the CAN data transmitted from the CAN nodes 11 and 13 as the transmission source via the CAN communication unit 30, and the CAN to be transmitted wirelessly among the received CAN data. A step of storing data in the buffer 33a is executed.

  When the wireless transmission timing TD1 assigned to the first relay device 21 shown in FIG. 7 has arrived, the master relay device 23 checks whether CAN data is stored in the buffer 33a every time a predetermined time T2 elapses. (See steps S201 and S202 in FIG. 11). If the CAN data is not accumulated in the buffer 33a, a CF-Poll frame for giving a transmission right to the first relay device 21 is transmitted (see process S203 in FIG. 11). In this example, since the control command CAN data is accumulated, as shown in the period TM2 in FIG. 8, the master relay device 23 grants a transmission right to the first relay device 21 together with the control command CAN data. In order to transmit the QoS Data + CF-Poll frame, the processing after processing S204 in FIG. 11 is executed. That is, as shown in FIG. 9A, when the CAN data accumulated in the command buffer and the device information buffer is single, after being stored in the work wireless transmission temporary memory (not shown), An MPDU payload is generated with the single CAN data, and is wirelessly transmitted to the first relay device 21 (see steps S204 in FIG. 11: NO, S205, and S207). On the other hand, as shown in FIG. 9B, when there are a plurality of CAN data accumulated in the command buffer and the device information buffer, the plurality of CAN data are aggregated to generate an MPDU payload. A batch transmission is performed wirelessly to the relay device 21 (see steps S204 in FIG. 11: YES, S206, S207). For the aggregate of frames, A-MSDU and A-MPDU defined in IEEE802.11n can be mentioned as a reference. Since these standards define an aggregate of Ethernet (registered trademark) frames, the MAC header of the Ethernet frame is included in the MPDU payload. However, in the present invention, since the data to be transmitted is not Ethernet frames but CAN data, the MAC header can be omitted from the MPDU payload, thereby reducing data and improving throughput. That is, the relay control unit 32a illustrated in FIG. 2 transmits the single CAN data to the other relay device 21 when the CAN data accumulated in the buffer 33a is single at the wireless communication timing. When there are a plurality of pieces of CAN data accumulated in the buffer 33a at the wireless transmission timing, a step of aggregating the plurality of pieces of CAN data and collectively transmitting to the other relay apparatuses 21 is executed.

  Next, the first relay device 21 receives wireless data from the master relay device 23 as shown in the period TM2 in FIG. 8 (see process S601 in FIG. 15). Here, since the received wireless data is QoS Data, and the CAN data is included in the wireless data, the reception processing after processing S602 in FIG. 15 is performed. When the received wireless data is data obtained by aggregating a plurality of CAN data, the wireless data is divided into individual CAN data. It is determined whether or not the received CAN data should be received (see step S603 in FIG. 15), and if it is determined that it should be received, it is stored in a temporary memory (steps S603 in FIG. 15: YES, see S605). For example, when ID = 1, it is determined that the data is to be received. If it is determined that the data should not be received, the data is discarded (see processing S603: NO, S604 in FIG. 15).

If CAN data is stored in the temporary memory of the first relay device 21 (see step S606: YES in FIG. 15), a CAN data frame is generated as shown in a period TM3 in FIG. The data is transmitted to one CAN node 11 (see process S607 in FIG. 15). That is, the relay control unit 32a illustrated in FIG. 2 executes a step of relaying the received CAN data to the CAN node 11 that is the reception destination via the CAN communication unit 30.

  Next, the first relay device 21 determines whether there is CAN data to be transmitted wirelessly in the buffer 33a (see step S608 in FIG. 15). If there is no CAN data, Ack is returned to the master relay device 23 (see step S613 in FIG. 15). Here, since the single device information CAN data is accumulated in the buffer 33a, as shown in the period TM4 in FIG. 8, an MPDU payload is generated with the CAN data and transmitted to the master relay device 23 by radio (FIG. 15). (See step S609: NO, S610, S612). When a plurality of pieces of CAN data are accumulated, the plurality of pieces of CAN data are aggregated and transmitted (refer to steps S609: YES, S611, and S612 in FIG. 15). Further, the wireless transmission process shown in FIG. 14 is also executed in parallel. That is, every time T2 elapses, it is confirmed whether or not CAN data is accumulated in the buffer 33a (see steps S501 and S502 in FIG. 14). If it is within the transmission permission time, an MPDU payload is generated and the master relay It transmits to the apparatus 23 by radio | wireless (refer process S503, S504, S505, S506, S507 of FIG. 14).

  Next, as shown by TM4 in FIG. 8, the master relay device 23 receives wireless data from the first relay device 21 (see processes S301 and S302 in FIG. 12). Here, since the wireless data is QoS Data, and the device information CAN data is included in the wireless data, the reception processing after processing S303 in FIG. 12 is performed. When the received wireless data is data obtained by aggregating a plurality of CAN data, the wireless data is divided into individual CAN data. The received CAN data is stored separately for each ID in the device information buffer shown in FIG. 3 (see process S303 in FIG. 12). Ack is returned to the first relay device 21 (see step S304 in FIG. 12). Next, the master relay device 23 generates a CAN data frame from the received CAN data and transmits it to the third CAN node 13 (controller 13) as shown in a period TM5 in FIG. 8 (processing in FIG. 12). (See S305, S306, S307, S308).

  Next, when the wireless transmission timing TD2 assigned to the second relay device 22 shown in FIG. 7 arrives, the master relay device 23 receives the device information CAN stored in the buffer 33a as shown in the period TM6 of FIG. Data (ID = 1) and control command CAN data (ID = 1) are wirelessly transmitted to the second relay device 22 (see the process of FIG. 11). When receiving this, the second relay device 22 generates a CAN frame and transmits the CAN data to the second CAN node 12 as shown in a period TM7 in FIG. 8 (see the processing in FIG. 15).

As described above, the CAN data relay device 21 (23) according to the present embodiment is provided corresponding to each of the CAN node 11 serving as a transmission source and the CAN node 13 serving as a reception destination. A device that relays CAN data to be communicated via a wireless network 10 constructed with another relay device 23 (21),
CAN communication unit 30 for communicating CAN data with CAN node 11 (13) via a wire, wireless communication unit 31 for wireless communication with another relay device 23 (21) at a predetermined wireless transmission timing, and CAN communication unit 30 Alternatively, the CAN communication unit 30 receives CAN data transmitted from the CAN node 11 (13) as a transmission source via the wireless communication unit 31, and directs the received CAN data toward the CAN node 13 (11) as a reception destination. Or a relay control unit 32a that relays via the wireless communication unit 31, and a buffer 33a for storing CAN data,
The relay control unit 32a stores CAN data to be wirelessly transmitted among the received CAN data in the buffer 33a. If the CAN data stored in the buffer 33a is single at the wireless transmission timing, the relay control unit 32a When one piece of CAN data is transmitted to the other relay device 23 (21) and there are a plurality of pieces of CAN data accumulated in the buffer 33a at the wireless transmission timing, the plurality of pieces of CAN data are aggregated and others. To the relay device 23 (21).

  With this configuration, CAN data is always transmitted at the wireless communication timing in a state where CAN data to be transmitted wirelessly is accumulated in the buffer 33a, so that there is no waiting until the CAN data becomes plural. . Therefore, it is possible to ensure the real-time property required for CAN communication, as compared with the case of waiting for a plurality of CAN data despite the wireless communication timing. If a plurality of pieces of CAN data to be transmitted wirelessly are accumulated in the buffer 33a, a plurality of CAN data are aggregated and wirelessly transmitted, so that the throughput can be improved. . Therefore, it is possible to achieve both improvement in the throughput of wireless communication and securing real-time performance.

  In particular, in the present embodiment, the wireless communication unit 31 performs wireless communication in conformity with the wireless LAN communication standard IEEE802.11, so that compatibility can be ensured accurately by using the standard.

  Further, in the present embodiment, when one relay device among the plurality of relay devices 21, 22, 23 belonging to the wireless network 10 is the master relay device 23 and the other relay devices are slave relay devices 21, 22, The master relay device 23 and the slave relay devices 21 and 22 can communicate with each other only at the wireless transmission timing determined by the master relay device 23. By sequentially switching the slave relay devices with which the master relay device 23 communicates, It is configured to execute QoS control that guarantees wireless communication of 21, 22, and 23.

  With this configuration, wireless communication between the relay apparatuses 21, 22, and 23 is guaranteed by QoS (Quality of Service) control, so that the wireless communication between the relay apparatuses 21, 22, and 23 can be avoided from colliding. Thus, communication quality can be improved.

  Furthermore, in this embodiment, since QoS control is performed using HCCA (Hybrid coordination function Controlled Channel Access) defined in the wireless LAN communication standard IEEE802.11e, compatibility is improved by using the standard. It becomes possible to ensure accurately.

This embodiment can be specified as a CAN data relay system. That is, the CAN data relay system according to the present embodiment includes a relay device 21 corresponding to the CAN node 11 serving as a transmission source and a relay device 23 corresponding to the CAN node 13 serving as a reception destination. 13 is a system that relays CAN data communicated via a wireless network 10 constructed by both relay devices 21 and 23,
Each relay device 21 (23)
A CAN communication unit 30 for communicating CAN data with the CAN node 11 (13) via a wire;
A wireless communication unit 31 that wirelessly communicates with another relay device 23 (21) at a predetermined wireless transmission timing;
The CAN communication unit 30 or the wireless communication unit 31 receives the CAN data transmitted from the CAN node 11 serving as the transmission source, and sends the received CAN data to the CAN node 13 serving as the reception destination. A relay control unit 32a relaying via the communication unit 31,
A buffer 33a for storing CAN data,
The relay control unit 32a stores CAN data to be wirelessly transmitted among the received CAN data in the buffer 33a. If the CAN data stored in the buffer 33a is single at the wireless transmission timing, the relay control unit 32a When one piece of CAN data is transmitted to the other relay device 23 (21) and there are a plurality of pieces of CAN data accumulated in the buffer 33a at the wireless transmission timing, the plurality of pieces of CAN data are aggregated and others. To the relay device 23 (21). This system can also achieve the above effects.

This embodiment can be specified as a CAN data relay method. That is, the CAN data relay method according to the present embodiment is a CAN node in a system including a relay device 21 corresponding to a CAN node 11 serving as a transmission source and a relay device 23 corresponding to a CAN node 13 serving as a reception destination. It is a method of relaying CAN data communicated with each other 11 and 13 via the wireless network 10 constructed by both the relay devices 21 and 23,
Of the CAN data received from the CAN node 11 (13) or the relay device 23 (21), the CAN data to be transmitted wirelessly is stored in the buffer 33a, and the CAN data stored in the buffer 33a at a predetermined wireless transmission timing is stored. When there is a single data, when the single CAN data is wirelessly transmitted to the CAN node that is the reception destination, there is a plurality of CAN data accumulated in the buffer 33a at the wireless transmission timing. Then, the plurality of CAN data are aggregated and wirelessly transmitted to a CAN node as a reception destination. The above effect can also be achieved by using this method.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  Further, as shown in FIG. 8, the master relay device 23 according to the present embodiment, for example, transmits the control command CAN data (ID = 1) to all CAN nodes regardless of the data contents. However, the master relay device may be configured as follows. In other words, the master relay device stores in advance association information 40 between the CAN node and the relay device connected to the CAN node by wire, and the CAN data accumulated in the buffer 33a is used as the CAN data reception destination. It is configured to transmit wirelessly only to the relay device associated with the CAN node. Specifically, as shown in FIG. 16A, the association information 40 associates the first CAN node 11 with the MAC address of the first relay device 21, and the second CAN node 12 and the second relay device 22. Is a table in which the third CAN node 13 and the MAC address of the third relay device 23 are associated with each other. In addition, as illustrated in FIG. 16B, association information 41 between a CAN ID and a CAN node that is a transmission destination is included. Then, the master relay device 23 refers to the ID of the CAN data to be transmitted wirelessly, identifies the CAN node as the transmission destination based on the association information 41, and sets the relay device corresponding to the identified CAN node in the association information 40. Identify based on. Then, the CAN data is transmitted only to the identified relay device.

  If the path control is performed according to the contents of the CAN data in this way, in the example of FIG. 8, the command data (ID = 1) is wirelessly transmitted only to the first relay device 21, and the first Since wireless transmission of CAN data to a relay apparatus that is not wirelessly transmitted to the second relay apparatus 22 and is associated with a CAN node that is not a reception destination can be omitted, throughput can be improved.

  In this embodiment, when a plurality of CAN data is aggregated, CAN data having different IDs may be included in one MPDU payload. However, all CAN data included in one MPDU payload may be included. The IDs may be the same. In this case, since the destinations of all the CAN data included in one MPDU payload are the same, it is preferable for wirelessly transmitting only to the relay apparatus associated with the CAN node as the reception destination as described above.

  Furthermore, in the present embodiment, the wireless communication unit 31 communicates the timing determined by the master relay device 23 as a predetermined wireless transmission timing on the assumption of QoS control, but is not limited thereto. For example, in an embodiment that does not presuppose QoS control, the wireless communication unit 31 may communicate a timing based on CSMA / CA as a predetermined wireless communication timing.

  In this embodiment, one CAN node is connected to one relay device by wire so that CAN communication is possible, but a plurality of CAN nodes are connected to one relay device by wire so that CAN communication is possible. May be. In this case, when a plurality of CAN nodes connected to one relay apparatus perform CAN communication, the relay apparatus does not participate in the communication.

  The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Wireless network 11, 12, 13 ... CAN node 21, 22, 23 ... Relay apparatus 23 ... Master relay apparatus 21, 22 ... Slave relay apparatus 30 ... CAN communication part 31 ... Wireless communication part 32a ... Relay control part 33a ... Buffer 40 ... Association information

Claims (7)

A CAN communication unit that communicates CAN data with a CAN node via a wire, a wireless communication unit that wirelessly communicates with another relay device at a predetermined wireless transmission timing, and a source via the CAN communication unit or the wireless communication unit CAN data transmitted from the CAN node to be received, relay control unit that relays the received CAN data to the CAN node that is the reception destination via the CAN communication unit or the wireless communication unit, and stores the CAN data And a buffer for
The relay control unit stores CAN data to be transmitted wirelessly in the received CAN data in the buffer, and when the CAN data stored in the buffer at the wireless transmission timing is single, When a plurality of CAN data accumulated in the buffer exists at the wireless transmission timing while a single CAN data is transmitted to another relay device, the plurality of CAN data are aggregated to another relay device. A CAN data relay device configured to be collectively transmitted to a device.   The CAN data relay device according to claim 1, wherein the wireless communication unit performs wireless communication conforming to a wireless LAN communication standard IEEE802.11.   The master relay device only at the wireless transmission timing determined by the master relay device when one relay device among the plurality of relay devices belonging to the wireless network is a master relay device and the other relay device is a slave relay device And the slave relay device can communicate with each other, and by sequentially switching the slave relay device that is the communication partner of the master relay device, QoS (Quality of Service) control that guarantees wireless communication between the relay devices is executed. The CAN data relay device according to claim 1, wherein the CAN data relay device is configured.   The master relay device stores in advance association information between a CAN node and a relay device connected to the CAN node by wire, and the CAN data accumulated in the buffer becomes a destination for receiving the CAN data. The CAN data relay device according to claim 3, wherein the CAN data relay device is configured to wirelessly transmit only to the relay device associated with the CAN node.   5. The CAN data relay apparatus according to claim 3, wherein QoS control is performed using HCCA (Hybrid coordination function Controlled Channel Access) defined in wireless LAN communication standard IEEE802.11e. A relay device corresponding to a CAN node as a transmission source and a relay device corresponding to a CAN node as a reception destination are provided, and CAN data communicated between CAN nodes is transmitted via a wireless network constructed by both relay devices. A relaying system,
Each relay device
A CAN communication unit that communicates CAN data with a CAN node via a wire;
A wireless communication unit that wirelessly communicates with another relay device at a predetermined wireless transmission timing;
The CAN communication unit or the wireless communication unit receives CAN data transmitted from a CAN node as a transmission source via the CAN communication unit or the wireless communication unit, and sends the received CAN data to the CAN node as a reception destination. A relay control unit that relays via
A buffer for storing CAN data,
The relay control unit stores CAN data to be transmitted wirelessly in the received CAN data in the buffer, and when the CAN data stored in the buffer at the wireless transmission timing is single, When a plurality of CAN data accumulated in the buffer exists at the wireless transmission timing while a single CAN data is transmitted to another relay device, the plurality of CAN data are aggregated to another relay device. A CAN data relay system configured to be collectively transmitted to an apparatus. In a system including a relay device corresponding to a CAN node as a transmission source and a relay device corresponding to a CAN node as a reception destination, a wireless network constructed by both relay devices is used to transmit CAN data communicated between CAN nodes. Via a relay method,
Of the CAN data received from the CAN node or the relay device, CAN data to be transmitted wirelessly is stored in a buffer, and when the CAN data stored in the buffer is single at a predetermined wireless transmission timing, When one piece of CAN data is transmitted wirelessly and there are a plurality of pieces of CAN data accumulated in the buffer at the wireless transmission timing, the plurality of pieces of CAN data are aggregated and wirelessly transmitted collectively. A CAN data relay method characterized by the above.

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