JP2009135567A - Data transfer apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transfer apparatus capable of reducing the processing load of a microcomputer while ensuring the safety of a communication system. <P>SOLUTION: A transceiver 13 extracts frame data including a frame ID representing the kind of data from an electric signal in transit over a communication bus A, and outputs the extracted frame data to a frame control module 17 via a CAN reception-dedicated module 50. The frame control module 17 temporarily stores the inputted frame data. A CAN transmission/reception module 25 takes out the frame data temporarily stored in the frame control module 17, and outputs the frame data to the transceiver 23. The transceiver 23 converts the inputted frame data into an electric signal, and outputs the converted electric signal to a communication bus B. Of the extracted frame data, the CAN reception-dedicated module 50 selectively outputs only the frame data for which transmission is permitted by the microcomputer 30 in advance to the frame control module 17. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a data transfer apparatus.

  2. Description of the Related Art Conventionally, as a data transfer device, a microcomputer (hereinafter referred to as a microcomputer) provided in the device is provided between a plurality of networks, and transfers data received from a network to another network. In addition, a data transfer device that controls a transfer path according to a load is known (see, for example, Patent Document 1).

As another data transfer apparatus, a data transfer apparatus that performs transfer control using a dedicated circuit instead of a microcomputer is known (for example, see Patent Document 2).
JP 2006-115260 A JP 2007-124602 A

  However, the technique described above (Patent Document 1) has a problem that the processing load on the microcomputer increases as the amount of data to be transferred increases. This problem will be described with reference to FIG. FIG. 5 is a block diagram schematically showing the configuration of the data transfer apparatus 101 whose transfer is controlled by the microcomputer 130.

  A data transfer apparatus 101 shown in FIG. 5 is connected to a network that performs communication using a CAN (Controller Area Network) protocol, and transfers data between networks.

  Specifically, the data transfer apparatus 101 is connected to a communication bus A constituting a first network and a communication bus B constituting a second network, and includes a transceiver 113 and a transceiver 123, a CAN transmission / reception module 115, and A CAN transmission / reception module 125, a frame control module 117 and a frame control module 127, and a microcomputer 130 are provided. The microcomputer 130 includes a communication module 131, a CPU 133, a ROM 134, and a RAM 135.

  The operation of each component will be described. The transceiver 113 is connected to the communication bus A and the CAN transmission / reception module 115, and the bus signal (<1 ′>) input from the communication bus A is transmitted to the CAN transmission / reception module 115. Is converted into a received signal that can be handled, and this received signal is output to the CAN transceiver module 115 (<2 ′>).

  The CAN transmission / reception module 115 is connected to the transceiver 113 and the frame control module 117. When a reception signal is input from the transceiver 113, the CAN transmission / reception module 115 extracts frame data from the signal and sends the frame data to the frame control module 117. Output (<3 '>).

  The frame control module 117 is connected to the CAN transmission / reception module 115 and the communication module 131. When frame data is input from the CAN transmission / reception module 115, the frame control module 117 receives the frame data as a first-in first-out (FIFO) type. Save in the frame storage area (<4 '>). Then, the CPU 133 extracts frame data stored in the received frame storage area of the frame control module 117 via the communication module 131 (<5 ′>).

  When the CPU 133 takes out the frame data stored in the frame control module 117, the CPU 133 analyzes the frame data. Specifically, based on a program stored in advance in the ROM 134, a process for reading frame ID, transfer destination, transfer cycle, and the like from the frame data is performed.

  Then, with reference to setting information indicating whether transfer is possible for each frame ID stored in the ROM 134 in advance, if the frame ID of the read frame data is set to transfer disable, the CPU 133 Discard the data without transferring it. On the other hand, if the read frame data can be transferred, the CPU 133 transfers the frame data whose transfer destination is the communication bus B to the frame control module via the communication module 131 in accordance with the read transfer cycle. It outputs to 127 (<6 ′>). Then, the frame control module 127 stores the frame data input from the CPU 133 in the FIFO-type transmission frame storage area (<7 ′>).

  The CAN transmission / reception module 125 is connected to the frame control module 127 and the transceiver 123. The CAN transmission / reception module 125 extracts frame data stored in the transmission frame storage area of the frame control module 127 (<8 '>), and the frame data Is transmitted to the transceiver 123 (<9 ′>).

  Finally, the transceiver 123 converts the transmission signal input from the CAN transceiver module 125 into a CAN bus signal and outputs this bus signal to the communication bus B (<10 ′>).

  By the way, the above-described data transfer control is like processing from <5 ′> to <6 ′>. For example, as the transfer control, a technique for controlling (filtering) specific frame data so that the frame data is not transferred to another network by selectively transferring only data that is permitted to be transferred in advance. It has been known.

  However, if the processing capacity of the microcomputer is frequently used for transfer control, there arises a problem that other processing is hindered. Specifically, in order to save cost and space, a communication device connected to a network is rarely designed exclusively for data transfer. That is, in this type of communication apparatus, various processes other than the data transfer control are executed by the microcomputer, and the processing capability that can be allocated for the transfer control is limited.

  One technique for solving this is the technique of Patent Document 2. Since this technology does not use a microcomputer, the above-mentioned problems do not occur at all. However, since the transfer device of Patent Document 2 is configured with simple hardware, there is a possibility that a large amount of data is transmitted regardless of the state of the network. In particular, when the transfer destination network is low-speed, transferring a large amount of data increases the load on the transfer destination network, leading to data delay, which is likely to cause a failure in vehicle control.

  The present invention has been made in view of these problems. While using a microcomputer, the processing load on the microcomputer can be reduced and an appropriate amount of data can be transferred according to the network conditions. An object is to provide a data transfer device.

  The data transfer device according to claim 1, which is made to achieve the above object, includes a buffer, a reception circuit, a transmission circuit, and setting means, and transmits data from the first network to the second network. The frame data in which the frame ID indicating the type is written is transferred.

  In this data transfer device, the receiving circuit is connected to the first network, extracts frame data from a transmission signal flowing through the first network, and outputs the extracted frame data to a buffer. The buffer stores (temporarily stores) frame data input from the receiving circuit. The transmission circuit is connected to the second network, extracts frame data stored in the buffer, and outputs a transmission signal storing the extracted frame data to the second network.

  The setting unit measures the transmission amount of the transmission signal flowing through the second network per unit time. Based on the measured transmission amount, the frame ID of the frame data that is permitted to be transferred is set for the receiving circuit. The function as the setting means can be realized by a microcomputer by a program.

  Then, the reception circuit selectively outputs only the frame data in which the frame ID of the frame data permitted to be transferred by the setting unit is written out of the extracted frame data to the buffer.

  Thus, in the data transfer apparatus of the present invention, the basic part of transfer control is realized by a receiving circuit that is hardware, not a microcomputer. Therefore, according to the present invention, the processing load on the microcomputer for data transfer can be reduced.

  Also, according to the present invention, it is possible to execute data transfer with a data amount corresponding to the bus load of the transfer destination communication bus. For example, if the transfer destination bus load is small, transfer is permitted for all frame IDs, while if the transfer destination bus load is large, transfer of frame data with a low importance level is prohibited. is there. Therefore, according to the present invention, it is possible to transfer an appropriate amount of data according to network conditions.

  In addition, when a transfer of an abnormal amount of frame data is requested due to a failure of a communication device connected to the first network, if the abnormal amount of frame data is transferred as it is, the second Since the network may also be abnormal, it is more preferable that the data transfer device is configured as described in claim 2.

  In the data transfer device according to claim 2, the setting means measures the transmission amount of the transmission signal flowing through the second network per unit time, and from the first network to the second network per unit time. Estimate the amount of frame data to be transferred. Then, based on the measured transmission amount and the estimated transfer amount, a frame ID of frame data that permits transfer to the receiving circuit is set.

  According to the data transfer device configured in this way, the above abnormality can be detected early by estimating not only the bus load of the transfer destination but also the amount of frame data requested to be transferred, When there is an abnormality, it is possible to execute processing such as setting a frame ID so as not to transfer all the frame data.

  Further, the data transfer device according to claim 3 is characterized in that the setting means according to claim 2 counts the total number of frame data extracted to the receiving circuit per unit time, so that the first unit per unit time. In this configuration, the amount of frame data transferred from the network to the second network is estimated.

  According to the present invention, the estimation of the amount of data required to be transferred from the first network to the second network can be realized by counting the number of frame data extracted by the receiving circuit. When the microcomputer realizes the above function, appropriate transfer control can be realized with a simple procedure while suppressing the load on the microcomputer.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a data transfer apparatus 1 to which the present invention is applied.
As shown in FIG. 1, a data transfer apparatus 1 according to the present embodiment is provided so as to be interposed in first and second networks that transmit information by a CAN protocol, and realizes data transfer between networks. is there. Specifically, the data transfer apparatus 1 is connected to a communication bus A constituting a first network and a communication bus B constituting a second network, and includes a transceiver 13 and a transceiver 23, a CAN transmission / reception module 15 and A CAN transmission / reception module 25, a frame control module 17, a frame control module 27, and a microcomputer 30 are provided. The microcomputer 30 includes a communication module 31, a CPU 33, a ROM 34, and a RAM 35.

  Further, the data transfer apparatus 1 includes a CAN reception dedicated module 50 including a reception selection register 55 connected to the transceiver 13 on the communication bus A side, and a reception selection register 65 connected to the transceiver 23 on the communication bus B side. And a CAN reception dedicated module 60, and a communication bus load monitoring unit 37 inside the microcomputer 30. These will be described in detail later.

  The operation of each component will be described. The transceiver 13 is connected to the communication bus A and the CAN transmission / reception module 15, and the CAN transmission / reception module 15 receives the bus signal (<1>) input from the communication bus A. The received signal is converted to a handleable signal, and the received signal is output to the CAN transceiver module 15 (<2>).

  The CAN transmission / reception module 15 is connected to the transceiver 13 and the frame control module 17. When a reception signal is input from the transceiver 13, the CAN transmission / reception module 15 extracts frame data from the signal and sends the frame data to the frame control module 17. Output (<3>).

  The frame control module 17 is connected to the CAN transmission / reception module 15 and the communication module 31. When frame data is input from the CAN transmission / reception module 15, the frame control module 17 receives the frame data as a first-in first-out (FIFO) type. Save in the frame storage area (<4>). In this embodiment, the frame data stored in the frame control module 17 is used for another process without being transferred.

  On the other hand, the CAN reception dedicated module 50 is connected to the transceiver 13 and the frame control module 27. When the reception signal (<2>) is input from the transceiver 13, the frame data is extracted from the signal and the frame ID is set. Only the frame data having a frame ID that is permitted to be transferred in advance is selectively output to the transfer destination frame control module 27 (<5>). The frame ID represents what information the frame data has. When the frame data is input from the CAN reception dedicated module 50, the frame control module 27 stores the input frame data in the FIFO type transmission frame storage area (<6>).

  The CAN transmission / reception module 25 is connected to the frame control module 27 and the transceiver 23, extracts frame data stored in the transmission frame storage area of the frame control module 27 (<7>), and converts the frame data into The stored transmission signal is generated and output to the transceiver 23 (<8>).

The transceiver 23 converts the transmission signal received from the CAN transmission / reception module 25 into a CAN bus signal and outputs the bus signal to the communication bus B (<9>).
Here, the operation of the CAN reception dedicated module 50 incorporating the reception selection register 55 described above will be described in detail. Similar to the CAN transmission / reception module 15, the CAN reception dedicated module 50 extracts the frame data from the reception signal when the reception signal is input from the transceiver 13 and inputs this to the transfer destination frame control module 27. Execute, but select only frame data to which a specific frame ID is assigned from the frame data extracted from the received signal based on the frame ID information described in the frame data and the contents of the reception selection register 55 Thus, it is input to the frame control module 27.

  FIG. 2 shows the configuration of the reception selection register 55. As shown in FIG. 2, the reception selection register 55 is configured to be able to switch the binarized potential level associated with each of all the frame IDs used in the CAN based on a command from the CPU 33. If the potential level corresponding to the frame ID described in the frame data extracted from the received signal is “HIGH”, the CAN reception-dedicated module 50 uses this frame data as the transmission frame of the transfer destination frame control module 27. Output to the storage area.

  On the other hand, if the potential level corresponding to the frame ID written in the frame data extracted from the received signal is “LOW”, the CAN reception dedicated module 50 outputs this frame data to the frame control module 27 of the transfer destination. Without interrupting the transfer of the frame data from the first network to the second network. The operation described here selectively outputs only the frame data having the frame ID permitted to be transferred in advance as described in the description of the CAN reception dedicated module 60 in <5> to the frame control module 27 of the transfer destination. This is a specific explanation of the operation.

  By the way, regarding the potential level of the reception selection register 55 described above, the CPU 33 receives the number of frames per unit time input to the reception frame storage area of the frame control module 17 and the transfer destination acquired from the communication bus load monitoring unit 37. Set based on communication bus load information.

  Next, a specific procedure for setting the potential level of the reception selection register 55 will be described with reference to FIG. FIG. 3 is a flowchart showing a potential level setting process that is repeatedly executed by the CPU 33 as a main component. This processing is intended for transfer from the communication bus A to the communication bus B.

  When this process is executed, the CPU 33 counts the number of frames stored in the received frame storage area of the frame control module 17 (S110), and then erases the counted frame data from the frame control module 17. (S120). Then, it is determined whether or not the counted number of frames is equal to or less than a predetermined threshold (S130).

  If it is determined that the counted number of frames exceeds a predetermined threshold (S130: No), the potential level of the reception selection register 55 is set to “LOW” for all frame IDs (S140). That is, in S130 and S140, it is monitored whether an abnormal amount of data is about to be transferred from the first network to the second network. If an abnormal amount of data is about to be transferred, communication is performed. All the potential levels of the reception selection register 55 are set to “LOW” so that the abnormality of the bus A does not reach the communication bus B. Then, after setting the potential level, the process waits for a predetermined time Tc while maintaining the setting, and thereafter, the potential level setting process is temporarily ended, and the above-described processes are executed again from S110.

  On the other hand, if the counted number of frames is equal to or less than the predetermined threshold (S130: Yes), the communication bus load monitoring unit determines whether the communication bus load of the communication bus B is 50% or more or less than 50%. Information is obtained from 37 and determined (S150).

  Here, a method of calculating the communication bus load will be described. The communication bus load monitoring unit 37 extracts frame data from the bus signal flowing through the communication bus B, counts the number of frames flowing through the communication bus B per unit time, and transmits the data transmission amount per unit time of the communication bus B. Calculate Then, a ratio between the calculated transmission amount and a maximum transmission amount that can be flown per unit time by the communication bus B is calculated.

  For example, it is assumed that a communication system including the communication bus A and the communication bus B employs a 500 kbps CAN communication protocol, and the amount of information of CAN frame data in a standard format is 108 bits. In this case, assuming that 1000 frame data is transmitted per second, the communication bus load is [108 (bit / frame data) × 1000 (frame data / second)] / 500,000 (bit / second) = 21.1. 6%.

  When the CPU 33 determines that the communication bus load is 50% or more based on the ratio information acquired from the communication bus load monitoring unit 37 (S150: Yes), the CPU 33 sets the cut-off rate setting table (see FIG. 4) to 50% or more. A process of transmitting a command for setting the potential level of the reception selection register 55 at a predetermined cycle Ts according to the set content of the associated cutoff rate is executed for a predetermined time Tc (S160). After that, the process is temporarily ended, the process proceeds to S110, the number of frames stored in the received frame storage area of the frame control module 17 is counted, and the processes after S120 are executed again based on the information.

  The blocking rate here is a value that determines how long the control period Tc should block the transfer of frame data. For example, when the blocking rate of a certain frame ID is set to a% and the control cycle is set to Tc seconds, the CPU 33 corresponds to the frame ID for (a / 100) · Tc seconds in Tc seconds. The potential selection level is set to “LOW” and the potential selection level corresponding to the frame ID is set to “HIGH” for (1-a / 100) · Tc seconds. On the other hand, the potential level corresponding to the frame ID is set to “HIGH” or “LOW”.

  FIG. 4 shows the configuration of the cutoff rate setting table stored in the ROM 34. As shown in FIG. 4, in this embodiment, all frame IDs are divided into a plurality of groups, and the blocking rate setting table is applied in each environment where the bus load is 50% or more and less than 50%. The set value of the blocking rate to be associated is associated with each grouped frame ID of each group.

  In the present embodiment, the blocking rate of each group to be applied when the transfer destination communication bus load is less than 50% is set to 0% in advance at the design stage. This is because it is not necessary to block the transfer of frame data if the communication bus load at the transfer destination is low.

  On the other hand, when the transfer destination communication bus load is 50% or more, the block rate of frame data having a frame ID of 0x000-0x0FF is 10%, and the block rate of frame data having a frame ID of 0x100-0x4FF is 30%. The cutoff rate of frame data having a frame ID of 0x500-0x7FF is set to 50%.

  The blocking rate can be set based on the importance of frame data transmitted with each frame ID. Here, since the frame data transmitted with the frame ID of 0x000-0x0FF is the most important data, the blocking rate is set low. On the other hand, for frame data transmitted with a frame ID of 0x500-0x7FF, since the importance is the lowest rank, the blocking rate is set high.

In this embodiment, the potential level of the reception selection register 55 is set in S160 according to the setting contents of the cutoff rate in the cutoff rate setting table having such a configuration.
On the other hand, when the CPU 33 determines that the communication bus load is less than 50% based on the ratio information acquired from the communication bus load monitoring unit 37 (S150: No), it is 50% in the cutoff rate setting table (see FIG. 4). A process for transmitting a command for setting the potential level of the reception selection register 55 at a predetermined cycle Ts according to the setting content of the cutoff rate associated with less than the predetermined time Tc is executed (S160). In this embodiment, since the cutoff rate is 0%, a command for setting the potential level of the reception selection register 55 is transmitted so that the potential level of all the frame IDs is maintained at “HIGH” for a predetermined time Tc. And when predetermined time Tc passes, the said process will be once ended and the process after S110 will be performed again.

  By the way, although the operation of the CAN reception dedicated module 60 incorporating the reception selection register 65 has not been described so far, the CAN reception dedicated module 60 incorporating the reception selection register 65 receives data from the communication bus B to the communication bus A. Operates when transferred.

  The CAN reception dedicated module 60 has the same configuration as the CAN reception dedicated module 50, and the data transfer operation from the communication bus B to the communication bus A is the same as the data transfer operation from the communication bus A to the communication bus B. To be realized. That is, the data transfer operation from the communication bus B to the communication bus A is basically the same as the data transfer operation from the communication bus A to the communication bus B, and the data transfer direction is at most opposite. .

Accordingly, a detailed description of the data transfer operation from the communication bus B to the communication bus A is omitted here, but a brief description is as follows.
That is, the transceiver 23 has the same configuration as the transceiver 13, and based on the bus signal input from the communication bus B, the transceiver 23 inputs a reception signal to the CAN reception dedicated module 60 and the CAN transmission / reception module 25. Extracts frame data from the received signal and inputs it to the frame control module 27. By this operation, the frame data extracted by the CAN transmission / reception module 25 is stored in the reception frame storage area of the frame control module 27. The number of stored frame data is transferred from the communication bus B to the communication bus A. This is used for setting the potential level of the reception selection register 65 at the time. The CPU 33 determines the reception selection register 55 based on the bus load of the communication bus A measured by the communication bus load monitoring unit 37 and the number of frame data stored in the reception frame storage area of the frame control module 27. Similarly to the setting of the potential level, the potential level of the reception selection register 65 is set.

  The CA reception dedicated module 65, in the frame data extracted from the received signal input from the transceiver 23, in accordance with the potential level setting contents of the reception selection register 65 set by the CPU 33 in this way, is permitted to be transferred. Data is selectively input to the frame control module 17 so that the frame data is stored in the transmission frame storage area of the frame control module 17.

  The frame data written in the transmission frame storage area of the frame control module 17 in this way is extracted by the CAN transmission / reception module 15, further converted into a transmission signal, and input to the transceiver 13. Finally, it is output as a bus signal to the communication bus A.

  The configuration of the data transfer device 1 according to the present embodiment has been described above. According to the data transfer device 1, a function for determining whether or not to transfer frame data by the CAN reception dedicated module 50 and the CAN reception dedicated module 60 is realized. Therefore, it is not necessary for the CPU 33 to analyze the information included in the frame data, and the processing load on the CPU 33 is reduced.

  That is, the CPU 33 switches the potential level of the reception selection register 55.65 through the communication module 31 so as to correspond to the cutoff rate based on the information on the communication bus load of the transfer destination acquired from the communication bus load monitoring unit 37. Since the transfer control can be realized at a level, transfer of the number of frames according to the communication bus load at the communication destination can be executed with a load sufficient to acquire and analyze information on the communication bus load.

  In addition, the CPU 33 can prevent the transfer source abnormality from spreading to the transfer destination with a load sufficient to count the number of frames transmitted to the frame control modules 17 and 27 per unit time.

  Here, the relationship between the invention described in claim 2 and the embodiment will be described. The setting means described in claim 2 is realized by S110 to S140 of the potential level setting process. Specifically, the processing of S110 and S120, which is executed periodically, “estimates the transfer amount that is the amount of frame data transferred from the first network to the second network per unit time” It corresponds to. Further, the processing of S130 and S140 corresponds to an operation of “setting a frame ID of frame data permitted to be transferred to the receiving circuit based on the estimated transfer amount”.

  Further, the present invention is not limited to the present embodiment, and can take various forms. For example, in the blocking rate setting table, the communication bus load may be divided into three types, and the blocking rate may be set according to them. In this way, it is possible to transfer data according to the communication bus load more appropriately. Further, a CAN reception dedicated module may be added. In this way, the data transfer according to the communication bus load can be performed more appropriately as the number of CAN reception dedicated modules increases.

1 is a block diagram showing a schematic configuration of a data transfer apparatus 1 to which the present invention is applied. 5 is a detailed diagram of a configuration relating to setting of a potential level of a reception selection register 55. FIG. It is a flowchart showing the electric potential level setting process which CPU33 performs. It is explanatory drawing showing the structure of the interruption | blocking rate setting table | surface. It is a block diagram which shows schematic structure of the data transfer apparatus by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Data transfer apparatus, 13 ... Transceiver, 15 ... CAN transmission / reception module, 17 ... Frame control module, 23 ... Transceiver, 25 ... CAN transmission / reception module, 27 ... Frame control module, 30 ... Microcomputer, 31 ... Communication module, 33 ... CPU 34 ... ROM, 35 ... RAM, 37 ... communication bus load monitoring unit, 50 ... CAN reception dedicated module, 55 ... reception selection register, 60 ... CAN reception dedicated module, 65 ... reception selection register, 101 ... data transfer device, 113 ... transceiver, 115 ... CAN transmission / reception module, 117 ... frame control module, 123 ... transceiver, 125 ... CAN transmission / reception module, 127 ... frame control module, 130 ... microcomputer, 131 ... communication module, 133 ... CPU, 134 ... ROM 135 ... RAM

Claims (3)

A data transfer device connected to a first network and a second network for transferring frame data in which a frame ID indicating a type of data is written from the first network to the second network;
A buffer to save the input frame data,
A receiving circuit connected to the first network, extracting frame data from a transmission signal flowing through the first network, and outputting the extracted frame data to the buffer;
A transmission circuit connected to the second network, extracting the frame data stored in the buffer, and outputting a transmission signal storing the extracted frame data to the second network;
Setting means for measuring a transmission amount of a transmission signal flowing through the second network per unit time, and setting a frame ID of frame data permitted to be transferred to the receiving circuit based on the measured transmission amount; ,
With
The receiving circuit selectively outputs only the frame data in which the frame ID of the frame data permitted to be transferred by the setting means is included in the extracted frame data to the buffer. apparatus. The setting means measures a transmission amount of a transmission signal flowing through the second network per unit time and transfers a frame data amount transferred from the first network to the second network per unit time. The frame ID of frame data permitted to be transferred is set for the receiving circuit based on the measured transmission amount and the estimated transfer amount. Data transfer device. The setting means counts the total number of frame data extracted by the receiving circuit per unit time, thereby allowing the frame data transferred from the first network to the second network per unit time. The data transfer device according to claim 2, wherein the transfer amount is estimated.

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