JP2009010852A - On-vehicle gateway device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gateway device reducing a communication load on a bus line and enabling stable communication. <P>SOLUTION: The on-vehicle gateway device has: a reception buffer temporarily storing a frame received from a first or second bus line for each kind of frame; a transmission buffer temporarily storing a frame transmitted to the second or first bus line; and a transmission means for transmitting the frame temporarily stored in the transmission buffer to the second or first bus line for a prescribed period. In this case, a plurality of kinds of frames temporarily stored in the reception buffer are rearranged in a single frame, and the single frame is stored in the transmission buffer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gateway device that relays a plurality of bus lines so that vehicle-mounted electronic control devices connected to different bus lines can communicate with each other.

  Conventionally, vehicles are equipped with various electronic control units (ECUs). These in-vehicle ECUs are connected to a common multiplex communication line to form a bus-type network and communicate information with each other. ing. In recent years, with the increase in the number of in-vehicle ECUs and the amount of information communicated between ECUs, bus lines can be grouped into several systems, such as powertrain systems and body electrical system systems. The amount of information transmitted and received on the bus line is prevented from becoming excessive.

  The grouped bus lines are connected to each other by the gateway device, so that vehicle-mounted ECUs connected to different bus lines can communicate with each other by relaying the gateway device.

  As a standard communication protocol between these in-vehicle ECUs, CAN (Controller Area Network) is known and widely used. In-vehicle gateway devices that perform information communication in units of frames within the CAN bus and relay communications between CAN buses, when receiving frames, transfer frames to other bus lines, whether they are frames transmitted or received within the same bus line. The frame is determined according to the type of the frame, and relaying is performed by blocking the frame from being transmitted to another bus line or by transferring it to another bus line.

An apparatus for relaying such a frame between bus lines is disclosed in Patent Document 1. Further, Patent Document 2 discloses a gateway device in which a network load on a bus line is measured and a transmission cycle is changed according to the load, thereby suppressing a communication load on the bus line.
JP 2000-244548 A JP 2006-287571 A

  By the way, it is considered that these types of in-vehicle ECUs and the amount of transmitted / received information will continue to increase in the future, and reduction of the communication load on the bus line is further desired. In the simplest case, if the number of control devices connected to one bus line is reduced by increasing the number of bus line systems, the communication load on each bus line is reduced. However, this method has a problem that the wiring is complicated and the cost is increased.

  In the technique of Patent Document 1, since a buffer is prepared for each type of data, data loss can be prevented, but communication load is not reduced. In the technique of Patent Document 2, the transmission cycle is adjusted according to the actual network load, so a certain effect can be expected, but the transmission cycle is changed according to the increase or decrease of the communication load, so the communication load becomes unstable. There is a demerit that it is easy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gateway device that can reduce and stabilize the communication load on the bus line.

  Therefore, in the in-vehicle gateway device according to the present invention, the first bus line and the second bus line are relayed, and the frames received from the first bus line or the second bus line are temporarily stored for each type. A reception buffer to store, a transmission buffer to temporarily store a frame to be transmitted to the second bus line or the first bus line, and a frame temporarily stored in the transmission buffer to the second bus at a predetermined cycle Transmitting means for transmitting to the line or the first bus line, and further rearranging a plurality of types of frames temporarily stored in the reception buffer into a single frame, and the single frame to the transmission buffer. Relocation means for storing. Therefore, the in-vehicle gateway device according to the present invention rearranges a plurality of frames received from the bus line into a single frame and transmits them in a predetermined cycle.

  Preferably, the rearrangement unit selects only predetermined information from the frame information stored in the reception buffer and rearranges the information in the single frame.

  Preferably, the predetermined information to be selected includes update recording means for recording whether or not each of the selected predetermined information has been updated since the last transmission frame was transmitted, and the rearrangement means records the update recording means in the record. If the predetermined information selected based on the information is not updated, information indicating that the information is not updated is added to the single frame. Accordingly, the single frame includes information indicating whether or not the information has been updated since the last transmission frame was transmitted. More specifically, the rearrangement unit indicates that the predetermined information is added to the single frame indicating that the selected predetermined information is not updated, and indicates the predetermined information in the single frame. This is realized by making the bit pattern of the area predetermined.

  Furthermore, preferably, a priority determination unit that determines a transmission priority for each of a plurality of types of frames temporarily stored in the reception buffer is provided, and the transmission unit performs recording by the priority determination unit and the update recording unit. On the basis of the above, the predetermined period may be shortened as the transmission priority of the updated frame among the plurality of types of frames temporarily stored in the reception buffer increases. If it does in this way, the vehicle-mounted gateway apparatus concerning this invention will rearrange and transmit in a short period, if a flame | frame with a high transmission priority is received.

  According to the present invention, a plurality of types of frames temporarily stored in the reception buffer are rearranged into a single frame, the single frame is stored in the transmission buffer, and transmitted to the bus line at a predetermined cycle. It is possible to reduce communication load and transmit (relay) frames stably.

(First embodiment)
FIG. 1 shows a network configuration diagram of a vehicle equipped with an in-vehicle gateway device according to an embodiment of the present invention. In this vehicle, a bus line 1 (first bus line) to which an electronic control unit (ECU) that mainly controls electrical components mounted on the vehicle body is connected, and a powertrain system ECU are mainly connected. The bus line 2 (second bus line) is connected by the gateway device 30 so as to be communicable. Specifically, an air controller ECU 11, a driving attention monitoring device ECU 12, a headlight optical axis adjusting device ECU 13, and the like are connected to the bus line 1. The bus line 2 is connected to an engine ECU 21, a transmission controller 22, an idle stop start (ISS) ECU 23, and the like, and is connected to a control device that is mainly required to have a relatively high communication speed. Each control device and gateway device 30 are each composed of a known central processing unit (CPU), electronic components such as RAM, ROM and the like.

  The network in FIG. 1 uses CAN (Controller Area Network) as a communication protocol. The ECU connected to each bus line transmits and receives information in frame units, and FIG. 2 shows an outline of the frame configuration. Since the frame structure in the CAN protocol is well known, a detailed description is omitted, but it includes an SOF indicating the start of the frame, an ID area given for each frame type, an area for data to be actually transmitted, etc. Is done.

  Each ECU that receives and transmits such a frame distinguishes the frame that it should receive by the ID number of the frame. For example, the engine ECU 21 connected to the bus line 2 transmits a frame including information such as the engine operating state on the bus line 2. Similarly, the transmission controller 22 connected to the bus line 2 reads the ID number of the frame transmitted on the bus line 2 and compares it with the ID number stored in advance as a frame to be received by the transmission controller 22. As a result, if there is a match, it is determined that the frame is to be received by itself, and if it is not, it is determined that the frame is not to be received by itself. In this way, communication is performed between ECUs that receive and transmit frames.

  On the other hand, when the gateway device 30 receives a frame, depending on the type of the gateway device 30, the gateway device 30 receives / transmits only between ECUs connected to one bus line, or receives / receives data from / to an ECU connected to another bus line. It is judged by referring to a previously stored table whether it is transmitted, and the frame is blocked or transferred.

  FIG. 3 shows a conceptual diagram of the recording area of the gateway device 30. The gateway device 30 has, as recording areas, a reception buffer 301 for temporarily storing a frame to be transferred, and an update flag recording area for checking whether or not the frame stored in the reception buffer is updated. 302 (update recording means). The reception buffer 301 is further divided in units of frames, and a storage area is determined for each frame type. For example, a frame transmitted from the engine ECU 21 is stored in a specific area 301 a in the reception buffer 301. The update flag storage area 302 is provided corresponding to the storage area provided for each type of frame, and records whether or not the corresponding frame has been updated (update recording means). In addition, the gateway device 30 includes a transmission buffer 303 that temporarily stores transmission frames, a table storage area 304 that indicates which bus line is received and transferred to which bus line for each frame type, and Is provided.

Next, functions of the gateway device 30 will be described with reference to the flowchart of FIG.
The gateway device 30 receives a frame, stores it in a reception buffer, and sets an update flag (step S100). When a frame is received, the received frame is stored in the reception buffer. As described above, since an area to be stored is determined in advance according to the type of the frame, it is stored in accordance with the determination. At this time, the corresponding flag is set in the update flag recording area 302 predetermined for each received frame. This process is repeated until a predetermined transmission cycle elapses (step S200).

  When the predetermined transmission cycle has elapsed, the gateway device 30 rearranges the reception frames temporarily stored in the reception buffer into a single frame (step S300). At this time, all the information shown in these received frames may be rearranged in a single frame, but in this embodiment, the information is selected. That is, a plurality of pieces of information are shown in one frame, but information that the gateway device 30 does not need to relay, that is, information that does not need to be transmitted to other ECUs across the bus line is also included. There may be. By omitting such information during rearrangement and selecting and rearranging only predetermined information, a plurality of frames can be rearranged into a single transmission frame, thereby reducing the communication load on the bus line. be able to.

  On the other hand, the information on the update flag is also taken into consideration in the rearrangement. That is, if the update flag is set, a new frame is received in the current transmission cycle, but if it is not set, no new frame is received in the current transmission cycle. Therefore, this information is included in a single transmission frame. Specifically, when the update flag is set, that is, when a new frame is received in the current transmission cycle, the information is used as it is. On the other hand, when the update flag is not set, that is, when a new frame is not received in the current transmission cycle, the information stored in the reception buffer is not used as it is, but a specific bit pattern is used. To form a single transmission frame.

  For example, when information selected to be included in a single transmission frame is 2-bit information, four bit patterns of “00”, “01”, “10”, and “11” can be expressed. Of these, “11” is determined in advance as a bit pattern when there is no update. By doing in this way, the data area in a transmission frame can be used effectively and the information on the presence or absence of an update can be added to a transmission frame efficiently. Of course, an area indicating the presence / absence of update may be added to a part of the transmission frame, but in that case, the data area that can be relocated in the transmission frame is reduced by that amount. The number of frames that can be rearranged is reduced, and as a result, the communication load increases.

  Then, the gateway device 30 transmits a single transmission frame stored in the transmission buffer onto the first bus line or the second bus line (step S400), and resets all the update flags 302 (step S400). S500).

  As described above, the gateway device 30 according to the present embodiment rearranges the information stored in the reception buffer for each frame type into a single frame and transmits it in a predetermined cycle. A plurality of different frames are relayed at a uniform timing. Thereby, the transmission cycle of the transmission frame relayed by the gateway apparatus 30 is stabilized, and the communication load of the entire system is stabilized. Further, since the information to be rearranged is selected, the data area of the transmission frame can be used effectively, and transmission can be performed with a single transmission frame, thereby reducing the communication load. Further, since update information is included in the transmission frame, the ECU that has received the information can distinguish whether or not the received information has been updated. That is, by rearranging a plurality of frames having different reception frequencies into a single frame at a predetermined timing, it is possible to prevent a situation in which the update of information is unknown. Since the presence or absence of the update does not become unknown, for example, a logic that determines that there is an abnormality when there is no update for a predetermined time or more can be established in the receiving ECU. Furthermore, since the predetermined transmission period can be set regardless of the reception period of the received frame, it can be set to an appropriate value in consideration of the communication load of the entire system in advance through experiments and desktop calculations, and it can be set according to the state of the vehicle. You can change it accordingly. That is, the load on the entire communication system can be stabilized by increasing the design freedom of the transmission cycle.

Although the present embodiment is configured as described above, these are merely examples, and the present invention is not necessarily limited to the contents. For example, in this embodiment, the update flag is set for each type of received frame, but may be set for each information unit selected by the rearrangement means. In this embodiment, only two bus lines are provided, but a gateway device that relays three or more bus lines may be used. In the present embodiment, only one type of single transmission frame is used. However, there may be a plurality of transmission frames in which a plurality of reception frames are rearranged into a single one. This is effective when the number of received frames and the amount of information are too large and it is difficult to rearrange all received frames into one transmission frame. In addition, various modifications can be made in consideration of technical common sense and the like without departing from the spirit of the present invention.

(Second embodiment)
The second embodiment further incorporates the concept of transmission priority in addition to the first embodiment. That is, in the first embodiment, the in-vehicle gateway device transmits a single transmission frame at a predetermined cycle, but in the second embodiment, a cycle for transmitting according to the importance of updated information is set. It is assumed to be variable.

  More specifically, in the second embodiment, only the process of step S100 in FIG. That is, in step S100 in the first embodiment, as soon as a frame is received, it is stored in the reception buffer and an update flag is set. In the second embodiment, the following processing is further performed. That is, a transmission priority is determined in advance for each received frame, for example, two types of transmission priority “medium (normal)” and “large (emergency)” are determined, and after the update flag is set, Check the frame transmission priority. That is, if the transmission priority of the received frame is “medium (normal)”, the transmission cycle is left as default, and if the transmission priority of the received frame is “high (emergency)” The transmission period is shorter than the default.

By doing so, the transmission cycle referred to in the next step S200 becomes variable, so when a frame with a high transmission priority is received, the process moves to step S300 in a shorter cycle and relays with good responsiveness. can do. Of course, it is possible to set the transmission priority to three or more levels. Even in such a case, it can be easily realized by setting the default value of the transmission cycle to the longest and shortening the transmission cycle each time a frame having a high transmission priority is received.

It is a network block diagram to which the in-vehicle gateway device of the present invention is applied. It is a block diagram of the data frame which the vehicle-mounted gateway apparatus of this invention receives / transmits. It is a conceptual diagram which shows the recording area | region of the vehicle-mounted gateway apparatus of this invention. It is a flowchart which shows the control performed in the vehicle-mounted gateway apparatus of this invention.

Explanation of symbols

30 In-vehicle gateway device 301 Reception buffer 302 Update flag 303 Transmission buffer

Claims (5)

An in-vehicle gateway device that relays between a first bus line and a second bus line,
A reception buffer for temporarily storing frames received from the first bus line or the second bus line for each type; and
A transmission buffer for temporarily storing frames to be transmitted to the second bus line or the first bus line;
Transmitting means for transmitting the frame temporarily stored in the transmission buffer to the second bus line or the first bus line at a predetermined cycle;
In-vehicle gateway device having
An in-vehicle gateway device comprising rearrangement means for rearranging a plurality of types of frames temporarily stored in the reception buffer into a single frame and storing the single frame in the transmission buffer.
The in-vehicle gateway device according to claim 1, wherein the rearrangement unit selects only predetermined information from the frame information stored in the reception buffer and rearranges the information in the single frame.
Each of the selected predetermined information includes update recording means for recording whether or not the information has been updated since the last transmission frame was transmitted,
The rearrangement unit adds information indicating that the information is not updated to the single frame when the predetermined information selected based on the record of the update recording unit is not updated. The in-vehicle gateway device according to 2.
The rearrangement means adds information indicating that the selected predetermined information has not been updated to the single frame, and sets a bit pattern of an area indicating the predetermined information in the single frame in advance. The in-vehicle gateway device according to claim 3, which is realized by making the predetermined one.
A priority determination means for determining a transmission priority for each of a plurality of types of frames temporarily stored in the reception buffer;
The transmission means, based on the recording by the priority determination means and the update recording means, among the multiple types of frames temporarily stored in the reception buffer, the higher the transmission priority of the updated frame, The in-vehicle gateway device according to claim 3 or 4, wherein the predetermined cycle is shortened.