JP4957569B2 - Data transfer system - Google Patents

Description

  The present invention relates to a system for transferring data.

  Conventionally, as a data transfer device constituting a data transfer system, when relaying networks between different communication protocols such as an event driven type and a time trigger type, and transferring data from one network to the other network, A device that converts data in accordance with a communication protocol is known.

  In this type of data transfer apparatus, there is a problem that data conversion is a burden on the CPU, memory, buffer, and the like. As a conventional invention aiming at solving the problem, a data transfer device configured to perform data conversion efficiently is known (for example, see Patent Documents 1 and 2).

Here, the event-driven and time-triggered communication protocols will be briefly described. An event-driven (event-driven) type communication protocol is represented by a CAN (Controller Area Network), and is a protocol that transmits a message when some event occurs. On the other hand, a time-triggered communication protocol is represented by FlexRay, and a message transmission schedule is determined in advance.
JP 2005-328119 A JP 2007-174053 A

  However, the above-described technique has a problem in that the load on the memory and buffer cannot be reduced, and a large-capacity memory and buffer are still necessary. In particular, this problem becomes prominent when data is transferred from an event-driven network to a time-triggered network. This is because the nodes constituting the event-driven network transmit data at a timing unrelated to the schedule referred to by the time-triggered communication protocol.

  That is, the data transfer device stores the transfer target data from the event-driven network until the transmission to the time-triggered network is permitted by the schedule. And must be stored in a buffer. For this reason, the conventional technique has a problem that a large capacity memory or buffer is required no matter how efficiently data is converted.

  The present invention has been made in view of the above-described problems, and provides a data transfer system that does not require a large-capacity memory when transferring data from an event-driven network to a time-triggered network. With the goal.

  The data transfer system according to claim 1 made to achieve this object comprises a data transfer apparatus and a node provided in the first network. The data transfer device is connected to a first network through which frame data is transmitted / received through an event-driven communication protocol and a second network through which frame data is transmitted / received through a time-triggered communication protocol. The transfer target frame data is transferred from the first network to the second network.

  The time-triggered communication protocol is a communication protocol determined to transmit each frame data to the second network at a specified time according to a predetermined schedule. In addition, a node provided in the first network executes transmission / reception of frame data according to the event-driven communication protocol.

  On the other hand, the data transfer device includes a first communication unit, a second communication unit, a determination unit, and a request unit. The first communication means is configured to transmit and receive frame data to the first network, and the second communication means is configured to transmit frame data to the second network.

  Further, the determination means is configured to be able to acquire information as to which frame data is the frame data transmitted through the second network among the frame data predetermined in the schedule. That is, the judging means collates the acquired information with the schedule so that the current time is a predetermined time before the transmission start time determined by the time-triggered communication protocol for the frame data to be transferred. It is determined whether it is time.

  When the requesting unit determines that the current time is a predetermined time before the transmission start time determined by the time-triggered communication protocol for the frame data to be transferred by the determining unit, The following operations are performed. The operation is to generate request frame data for requesting the frame data to be transferred and to the node in the first network capable of transmitting the frame data to be transferred to the data transfer apparatus. The generated request frame data is transmitted to the first communication means.

  In addition, when a node constituting the data transfer system provided in the first network receives the request frame data, the frame data to be transferred is transferred via the first network according to the request frame data request content. Send to device.

  Then, the second communication means transmits the frame data to be transferred received by the first communication means through the first network to the second network at a specified time according to the schedule.

  In other words, this data transfer system is configured to request transmission of frame data to be transferred from a node that communicates using an event-driven communication protocol in accordance with the schedule of the time-triggered communication protocol. .

  Therefore, in the prior art, the time from when the frame data to be transferred is received from the first network to when it is transmitted to the second network is random, but in the present invention, it can be controlled. .

Therefore, according to the present invention, naturally, the capacity of the storage medium for storing the frame data to be transferred can be reduced.
The data transfer system according to claim 1 may be configured as described in claim 2. The data transfer apparatus according to the second aspect is configured such that the determination unit and the request unit repeatedly operate, and includes a prohibition unit.

  If the first communication means does not receive the frame data to be transferred requested by the request frame data within a predetermined time after transmitting the request frame data, the prohibition means It is configured to be able to prohibit the requesting means from generating the next requested frame data for requesting the frame data to be transferred that has not been received.

  That is, this data transfer system prohibits transmission of request frame data from the next when it does not return even if request frame data is transmitted. Therefore, according to the present invention, it is possible to prevent wasteful use of the processing capacity of the data transfer apparatus when the requested node is stopped.

  The data transfer system according to claim 1 or 2 may be configured as described in claim 3. In the data transfer system according to claim 3, the requesting unit stores the waiting time information in the request frame data to be generated. When the node receives the request frame data in which the waiting time information is stored, the node is requested by the request frame data after the waiting time indicated by the request frame data has elapsed from the time when the request frame data is received. The frame data to be transferred is transmitted to the data transfer device.

  That is, according to the data transfer system of the present invention, it is possible to cause the node that has received the requested frame data to wait for transmission of the frame data to be transferred for the time indicated by the waiting time information. Accordingly, since the request frame data can be transmitted when the processing load of the data transfer apparatus is small and transmission of the frame data to be transferred can be reserved for the node, the processing load of the data transfer apparatus can be leveled. it can.

  The data transfer system according to any one of claims 1 to 3 may be configured as described in claim 4. According to a fourth aspect of the present invention, there is provided a data transfer device comprising a prediction means.

  The prediction means predicts a delay time which is a time from when the request frame data generation means generates the request frame data until the second communication means can transmit the frame data to be transferred to the second network. Then, the determination unit sets the predetermined time as the delay time predicted by the prediction unit.

  That is, according to this data transfer system, the time for transmitting the request frame data can be changed based on the delay time. Therefore, according to the present invention, there is no need to set a long delay time in advance, and the frame data to be transferred can be transmitted through the second communication unit immediately after being received through the first communication unit. The capacity of the storage medium can be further reduced.

  Note that the predicting means described in claim 4 may be specifically configured as described in claim 5. The predicting means in the data transfer system according to claim 5 comprises network load measuring means for measuring the load of the first network, and predicts the delay time based on the measurement result of the network load measuring means.

  That is, in the data transfer system of the present invention, the network load is measured by utilizing the fact that the delay time depends on the network load, and the measurement result is used for prediction of the delay time. Therefore, the request frame data can be transmitted based on the probable delay time, and the capacity of the storage medium can be further reduced.

  The data transfer system according to claim 4 or claim 5 may be specifically configured as in claim 6. A data transfer apparatus according to a sixth aspect includes a CPU and a program storage unit (memory or the like) for storing a program executed by the CPU. And this CPU implement | achieves the function as a judgment means, a request means, and a prediction means by running the program memorize | stored in the program memory means. Further, this program is configured so that the CPU can execute a process of measuring the processing load of the CPU as a process corresponding to the predicting unit and predicting the delay time based on the measurement result of the processing load.

  When all or part of the means of the data transfer apparatus is realized by software, the delay time depends on the processing load of the CPU. Therefore, in the present invention, this is used to measure the processing load on the CPU and to help estimate the delay time. Therefore, according to this data transfer system, the transmission time of the requested frame data can be determined based on a probable prediction of the delay time, and the capacity of the storage medium can be further reduced.

  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 system 1 to which the present invention is applied. The data transfer system 1 includes a plurality of nodes (nodes 111, 113, 115, ..., 121, 123, 125, ..., 211, 213, 215, ..., 221, 223, 225, ...) and a data transfer device 2. And a plurality of buses (buses B11, B12, B21, B22...).

  More specifically, the plurality of nodes are classified into two types. The first is a node configured to communicate by CAN, which is an event-driven communication protocol, and belongs to the first network (nodes 111, 113, 115, ..., 121, 123, 125, ...). ). The second is a node configured to communicate by FlexRay, which is a time-triggered communication protocol, and belongs to the second network (nodes 211, 213, 215, ..., 221, 223, 225, ...). ).

  Each of these nodes (nodes 111, 113, 115, ..., 121, 123, 125, ..., 211, 213, 215, ..., 221, 223, 225, ...) is one of the buses (buses B11, B12, B21). , B22..., And is configured to transmit / receive frame data to / from other nodes via the bus.

  In the following, among the buses described above, a set belonging to the first network is referred to as a first bus group B1, and a set belonging to the second network is referred to as a second bus group B2.

  The data transfer apparatus 2 includes a control unit 3 and a plurality of communication units (communication units 11, 12,..., 21, 22,...). Specifically, the control unit 3 is a known microcomputer including a CPU 5, a ROM 7, a RAM 8, and an NVRAM 9.

  Each communication unit (communication unit 11, 12,..., 21, 22,...) Is a well-known hardware that connects any of the buses (buses B11, B12,..., B21, B22...) And the control unit 3. Hardware (communication interface). Each of these communication units has the following functions. The function is to extract the frame data transmitted on the bus connected to itself and send it to the control unit 3, receive the frame data from the control unit 3, and output it to the connected bus, This is a function for monitoring which frame data is being transmitted.

  Each communication unit further includes a bus load measurement unit (bus load measurement units 110, 120, ..., 210, 220 ...). The bus load measuring unit has a function of monitoring the bus load of the bus connected to the communication unit to which it belongs and sending the information to the control unit 3.

  With such a configuration, the data transfer device 2 is connected to the first network and the second network, and is configured to transfer frame data transmitted and received between the first network and the second network. . Details will be described later.

  Next, the configuration of the node 111 connected to the bus B11 will be described with reference to FIG. FIG. 2 is a diagram showing the configuration of the node 111. The node 111 includes a control unit 1113 and a communication unit 1110. The control unit 1113 is a known microcomputer including a CPU 1115, a ROM 1117, and a RAM 1118. As described above, frame data is transmitted by CAN.

  The communication unit 1110 is configured by hardware (a CAN communication interface), and connects the bus B11 and the control unit 1113. Then, according to the CAN protocol, the frame data transmitted on the bus B11 is extracted and sent to the control unit 1113, or the frame data is received from the control unit 1113 and output to the bus B11.

  Incidentally, the configurations of all other nodes (nodes 111, 113, 115,..., 121, 123, 125,...) Connected to any one of the first bus group B1 are also shown in FIG. Is the same. However, the bus from which frame data is extracted and output is not limited to the bus B11, but is a bus (any one of the bus B11, the bus B12,...) Connected to each node.

  The nodes belonging to the second network are not characteristic according to the present invention, and receive frame data or transmit frame data using FlexRay according to the prior art. Therefore, here, the configuration of the nodes belonging to the second network will be briefly described.

  As is well known, FlexRay is a time-triggered communication protocol. Specifically, the communication cycle is subdivided into a plurality of time frames (time slots) in advance. Then, the subdivided time slot is allocated to each node constituting the network. In this way, it is possible to avoid overlapping transmission times of the nodes. That is, individual time slots are allocated in advance to each node constituting the second network. In the data transfer device 2, individual time slots are assigned in advance for each bus.

  Each node and the data transfer device 2 constituting the second network, when a time slot assigned to itself arrives, determines that the right to transmit is given and transmits data to be transmitted in the time slot to the second network. Is configured to output. In this way, each node and the data transfer device 2 configuring the second network transmit frame data to the second network at a specified time according to a predetermined schedule so that no communication collision occurs. Operate.

  Next, the request process will be described with reference to FIG. This request process is a process repeatedly executed mainly by the CPU 5 included in the data transfer apparatus 2. First, an outline of request processing will be described.

  In this embodiment, frame data to be transferred (hereinafter referred to as transfer frame data) is transferred from one of the first bus group B1 (any of bus B11, bus B12,...) To bus B21. When transferring by processing, it is necessary to perform the following operations.

  The operation refers to a communication unit (any of communication units 11, 12,...) Connected to the bus from any one of the first bus group B1 (any of bus B11, bus B12,...). The transfer frame data is stored in the RAM 8 until the transfer frame data is transmitted to the bus B 21 via the communication unit 21 after the transfer frame data is received.

  Incidentally, in this embodiment, it is assumed that the transfer frame data is predetermined by the designer at the design stage. Information on transfer frame data determined at the design stage is described in a schedule table to be described later.

  In the prior art, since the time for storing such transfer frame data in the RAM 8 is random without being controlled, it is necessary to increase the capacity of a storage medium such as a RAM. Therefore, in this embodiment, for the purpose of controlling the time, the request process is executed by the following processing procedure. In the present embodiment, this controls the request timing for the transfer source node of the frame data to be transferred.

  In the following description, an example in which request frame data is transmitted to transfer frame data to be transferred from the first network to the bus B21 among the buses constituting the second bus group B2 will be described. .

  This request processing will be described in detail. First, the CPU 5 connects each bus (bus B11, B12,...) From each communication unit (communication units 11, 12,...) Connected to each bus (buses B11, B12,...) Of the first bus group B1. Information on the bus load is acquired (S303). The bus load here is a value indicating how many frame data are actually transmitted per unit time to the bus with respect to the number of frame data that the bus can transmit per unit time.

  Next, the processing load of the CPU 5 itself is calculated (S307). Then, based on the bus load information acquired in S303 and the CPU processing load information calculated in S307, the delay time is estimated for each bus (buses B11, B12,...) (S310).

  Note that the delay time here refers to the request frame in the transfer process described later from the time when the request frame data is transmitted via the communication unit (any of the communication units 11, 12,...) In S350. This is the time required until the transfer frame data requested by the data can be transferred to the second network via the communication unit (any one of the communication units 21, 22,...). This delay time is affected by the bus load value of the bus to which the destination frame data destination node is connected and the processing load value of the CPU 5 itself. Therefore, in this embodiment, the delay time is estimated based on these two values.

  A specific example of the delay time estimation method will be described below. The relationship between the delay time and the bus load and its own processing load is obtained in advance by experiments and stored in the ROM 7 as a three-dimensional map. That is, through experiments, a three-dimensional map with axes of delay time, bus load, and CPU processing load as parameters (parameters) is generated and stored in the ROM 7 in advance. In S310, the delay time is estimated by determining the delay time corresponding to the current bus load and CPU processing load from the three-dimensional map stored in the ROM 7.

  Next, the monitoring information is acquired from the communication unit 21, and the monitoring information is applied to the schedule data to obtain the current time on the schedule (S320). The monitoring information is information indicating which frame data defined in the schedule is transmitted on the bus B21 and information on the elapsed time from the transmission start time of the frame data.

  FIG. 4 is a specific example of schedule data used in FlexRay. This is used only by the control unit and the control unit 3 included in the nodes (nodes 211, 213, 215,...) Connected to the bus B21. In this embodiment, it is assumed that unique schedule data is used in each bus (bus B21, bus B22,...) Of the second bus group B2.

  The same schedule data is stored in the storage medium (memory or the like) provided in each node (nodes 211, 213, 215,...) Connected to the bus B21 and the NVRAM 9 provided in the control unit 3. However, since each node (nodes 211, 213, 215,...) Connected to the bus B21 does not need transfer source information and transfer necessity information described later, these nodes (nodes 211, 213, 215,. ...) does not store transfer source information and transfer necessity information. Then, transmission of frame data to the bus B21 is performed according to this schedule data.

  The schedule data will be described in detail. The schedule data has transmission order information, a frame data name, a message slot length, transfer source information, and transmission necessity information for each frame data flowing through the bus B21. The transmission order information is information indicating the transmission order of the corresponding frame data in the bus B21, and the frame data name is identification information of the frame data used in the bus B21. The message slot length represents the time allocated for transmission of the corresponding frame data.

  The transfer source information indicates the identification code of the bus to which the transfer source node of the frame data specified by the frame data name belongs. This information is used to specify a bus to which request frame data described later is to be transmitted. For frame data whose transfer source information is empty information, this indicates that the frame data is not transfer frame data.

  The transmission necessity information is information indicating whether or not it is necessary to transmit the requested frame data for requesting the frame data to the transfer source node of the frame data specified by the frame data name. The transmission necessity information indicates a value corresponding to “necessary” or “unnecessary”. Note that the value indicated by the transmission necessity information is switched to “necessary” or “unnecessary” by the operation of the CPU 5 in S590 of the transfer process described later.

  Then, the storage medium included in each node (nodes 211, 213, 215,...) Connected to the bus B21 and the NVRAM 9 included in the data transfer device 2 determine which frame data transmission is allocated to itself by the CPU 5. Allocation information is stored in the NVRAM 9 or the like so that it can be performed.

  Next, the “current time on the schedule” obtained in S320 will be described. This time is set so that the transmission start time of the frame data of the transmission order 1 is zero seconds, and returns to zero every time the transmission order is completed. As a specific example, it is assumed that frame data B is being transmitted, and 8 ms has elapsed since the start of transmission of frame data B. At this time, the current time is 18 ms obtained by adding 8 ms to the message slot length of 10 ms of the frame data A. In this embodiment, such a time axis is determined, and the current time on the schedule is obtained.

  Return to the explanation of request processing. When the processing in S320 is completed as described above, the CPU 5 transfers the transfer frame data obtained in S310 at the current time estimated in S320 for each of the transfer frame data registered in the schedule data. It is determined whether the time obtained by adding the delay time of the bus to which the node is connected is the transmission start time of the transfer frame data (S330).

  This determination can be performed by the following procedure, for example. First, transfer frame data A having the earliest transmission order among transfer frame data registered in schedule data is targeted. According to the schedule data, the bus to which the transfer source node of the transfer frame data A is connected is the bus B11.

  Therefore, next, a time obtained by adding the delay time of the bus B11 to the current time is obtained. Then, it is determined whether this time coincides with the transmission start time of the transfer frame data A specified from the schedule data. Then, this determination is performed in the order of transmission order for all transfer frame data included in the schedule data, and it is determined whether there is a match.

However, transfer frame data in which the request frame data transmission necessity information of the schedule data is set to “unnecessary” is excluded from the processing target of S330.
In this way, the CPU 5 executes the process of S330. However, it is necessary to repeat the request process sufficiently early in order for the two times to be compared to completely match. However, if request processing is repeatedly executed at high speed, a large processing load is applied to the CPU 5. Therefore, in the present embodiment, a tolerance may be included in the delay time, and the criteria for determining whether the two times match may be relaxed. In other words, the time obtained by adding the delay time to the current time is widened, and in S330, it is determined whether or not the transmission start time is included in the time zone, so that the time obtained by adding the delay time to the current time is determined. It may be determined whether it is the transmission start time of the transfer frame data.

  In this case, it should be noted that if the tolerance of the delay time is reversed, when the transfer frame data is received, the transmission start time of the transfer frame data may pass. This is because if there is a negative tolerance, there is a possibility that a match is determined in S330 based on a time shorter than the actual delay time.

  In that case, it is necessary to store the transfer frame data in the RAM 8 for a time corresponding to approximately one communication cycle indicated by the schedule data, and the object of the present invention cannot be achieved. Therefore, the delay time tolerance is preferably set to such a size that only positive swinging can be performed and that a coincidence can be reliably determined in S330.

  Returning to the description of the request processing, if any transfer frame data is determined that the time obtained by adding the delay time to the current time is not the transmission start time of the transfer frame data (S330: No), the CPU 5 determines its own CPU. It is determined whether the processing load is equal to or less than a predetermined threshold (S335). If it is determined that the CPU processing load is not equal to or less than the predetermined threshold (S335: No), the process returns to S310. That is, the processes from S310 to S335 are repeated until it is determined Yes in S330 or S335.

  Then, when it is determined that the time obtained by adding the delay time to the current time for a certain transfer frame data is the transmission start time of the transfer frame data (S330: Yes), request frame data for requesting the transfer frame data is generated. Then (S340), the process proceeds to S350. This request frame data includes transfer frame data identification information. This transfer frame data identification information is information for identifying transfer frame data that is determined to be a time before the transmission start time. The transfer frame data identification information is transmitted to the node that has received this request frame data. Information requesting that data be transmitted to the bus to which the node is connected.

  On the other hand, when determining that the CPU processing load is equal to or less than the predetermined threshold (S335: Yes), the CPU 5 generates request frame data including information on the waiting time for the transfer frame data having the shortest waiting time ( S345), the process proceeds to S350. This request frame data includes waiting time information in addition to transfer frame data identification information. The waiting time information is set so that the node waits for the output of the transfer frame data for a predetermined time after the node receives the request frame data and outputs the transfer frame data in response to the request. This is information to be indicated and represents the waiting time.

  The waiting time is calculated for each transfer frame data as follows. That is, the waiting time is calculated as a time obtained by subtracting the current time from the transmission start time of the transfer frame data specified by the schedule data and further subtracting the delay time for the transfer frame data.

  The reason for generating the request frame data for the transfer frame data with the shortest waiting time in this way in S345 will be described below. The reason is that, when No is repeated in S330 and S335, the transfer frame data is most likely to be the transfer frame data to be determined as Yes earliest in S330.

  The purpose of the processes of S335 and S345 is to level the processing load of the CPU 5. That is, when it is determined Yes in S330, the processing load on the CPU 5 may be high. Therefore, if the current processing load is low, the request frame data requesting the transfer frame data to be transmitted next is transmitted at that time without waiting for Yes in S330. By doing so, it is not necessary to generate / transmit requested frame data when the processing load on the CPU 5 is high, and it is possible to prevent the processing load on the CPU 5 from further increasing.

  For this reason, in this embodiment, when the CPU processing load is small, the time required from the current time until it is determined Yes in S330 is calculated, and the time is stored in the request frame data as waiting time information. Like to do.

  In S350, the CPU 5 outputs the request frame data generated in S340 or S345 to a predetermined bus through the communication unit. The predetermined bus is a bus indicated by schedule data transfer source information, in other words, a node that can respond to the requested frame data (any of nodes 111, 113, 115,..., 121, 123, 125,...). Is a connected bus (any of buses B11, B12,...).

  That is, here, the request frame data is output to a communication unit (any one of the communication units 11, 12,...) Connected to the bus indicated by the schedule data transfer source information. Thereafter, the request processing is finished.

  For example, for the transfer frame data A (see FIG. 4), it can be seen from the transfer source information of the schedule data that the transfer source node is connected to the bus B11. Therefore, when request frame data requesting the transfer frame data A is output, the request frame data is output to the bus B 11 through the communication unit 11.

  As described above, the request processing described above is performed on the request frame data of the transfer frame data to be transferred to the bus B21 only for the bus B21 among the buses belonging to the second bus group B2. In accordance with the schedule, the data is transmitted to the transfer source node.

  The control unit 3 according to the present embodiment executes such request processing by the CPU 5 and also executes similar request processing for the other buses of the second bus group B2. In this way, request frame data of transfer frame data to be transferred to each of the buses B21, B22,... Is transmitted to the transfer source node in accordance with the schedule of the buses B21, B22,.

  Next, a response process repeatedly executed mainly by the CPU 1113 included in the node 111 will be described with reference to FIG. By executing the response process, the CPU 1113 receives the request frame data transmitted from the data transfer apparatus 2 by the request process described above, and returns the transfer frame data in response thereto.

  First, the CPU 1113 waits until it acquires frame data transmitted on the bus B11 via the communication unit 1110 (S410). Then, when any frame data is acquired, it is determined whether or not the frame data is request frame data addressed to itself (S420). Specifically, it is determined whether or not the acquired frame data is request frame data. If the acquired frame data is request frame data, the frame data identification information included in the request frame data is used. It is determined whether or not the transfer frame data to be generated can be generated by itself.

  The acquired frame data is the request frame data, and the acquired frame data is only obtained when the transfer frame data specified by the frame data identification information included in the request frame data can be generated by itself. It is determined that the request frame data is addressed to itself.

If it is determined that the acquired frame data is not the requested frame data addressed to itself (S420: No), the CPU 1113 ends the response process.
On the other hand, when determining that the acquired frame data is the requested frame data addressed to itself (S420: Yes), the CPU 1113 generates the transfer frame data requested by the request frame data based on the transfer frame data identification information. (S450).

  Next, the CPU 1113 determines whether or not standby time information is included in the acquired request frame data (S460). If it is determined that the request frame data includes the waiting time information (S460: Yes), the request frame data waits for the time indicated by the waiting time information (S470). Then, after the waiting time has elapsed, the generated transfer frame data is output to the bus B11 to which the communication unit 1110 is connected via the communication unit 1110 (S480).

  On the other hand, if it is determined that the request frame data does not include the waiting time information (S460: No), the CPU 1113 outputs the generated transfer frame data to the bus B11 via the communication unit 1110 immediately after the generation. (S480), and the response process ends.

  The CPU 1110 of this embodiment receives the request frame data transmitted from the data transfer apparatus 2 by the request process by executing the response process in such a procedure, and returns the transfer frame data in response thereto. .

  In this embodiment, it is a node belonging to the first network connected to any bus (any one of the buses B11, B12,...) Of the first bus group B1, and can generate and output transfer frame data. It is assumed that all the nodes are configured to be able to execute a response process similar to the response process executed by the CPU 1110 described above. However, in the description corresponding to S410 and S480, “bus B11” is replaced with the bus to which each node is connected.

  Next, the transfer process will be described with reference to FIG. This transfer process is a process repeatedly executed mainly by the CPU 5 of the data transfer apparatus 2. In the data transfer apparatus 2 of the present embodiment, the CPU 5 executes this transfer process, whereby the transfer frame data received from any of the buses of the first bus group B1 (buses B11, B12...) The data is transferred to one of the bus groups B2 (buses B21, B22,...).

  When this transfer process is started, the CPU 5 firstly selects any of the communication units (communication units 11, 12,...) Connected to the bus from any bus (bus B11, B12...) Of the first bus group B1. ) To determine whether transfer frame data has been received (S510).

  Then, transfer frame data is received from any of the buses of the first bus group B1 (buses B11, B12,...) Via a communication unit (any of the communication units 11, 12,...) Connected to the bus. If it is determined (S510: Yes), the transfer frame data format is converted from the CAN format to the FlexRay format to generate transfer frame data for second network output, and the generated transfer frame data is The data is stored in the RAM 8 (S520).

  On the other hand, when it is determined that no transfer frame data has been received from any bus (bus B11, B12...) Of the first bus group B1 via the communication unit (communication units 11, 12,...) (S510: No). ), The process of S520 is not performed, and the process proceeds to S530.

  In S530, it is determined whether transfer frame data is stored in the RAM 8. Incidentally, since this transfer process is repeatedly performed, there is a possibility that the transfer frame data is stored in the RAM 8 even if it is determined No in the immediately preceding S510.

  If it is determined that the transfer frame data is not stored in the RAM 8 (S530: No), the process proceeds to S580. On the other hand, if it is determined that the transfer frame data is stored in the RAM 8 (S530: Yes), the stored transfer frame data is transmitted to any of the buses belonging to the second bus group B2. It is specified based on the schedule data of each bus (S540).

  Then, for all the buses identified in S540, monitoring information of frame data transmitted through the bus is transmitted from the communication unit (any of the communication units 21, 22,...) Connected to the bus in the same manner as in S320. Obtaining and applying the monitoring information to the schedule data, the current time on the schedule data is obtained (S550).

  Then, based on the current time information obtained in S550, it is determined whether or not the current time is a transmission start time for any transfer frame data stored in the RAM 8 (S560). If it is determined that the current time is the transmission start time for any transfer frame data stored in the RAM 8 (S560: Yes), the transfer frame data that is determined to be the transmission start time is S540. The transfer frame data is output to the output target bus specified in step 1 via the communication unit corresponding to the bus, and the information of the transfer frame data is discarded from the RAM 8 (S570), and the process proceeds to S580. On the other hand, if it is determined that the current time is not the transmission start time of any transfer frame data (S560: No), the process proceeds to S580 without performing the process of S570.

  In step S580, the CPU 5 determines whether there is transfer frame data that could not be received by the transmission start time for each transfer frame data registered in the schedule data. Note that the processing of S580 is based on the premise described below. The premise is that, if the data transfer system 1 is operating normally, the data transfer device 2 always receives each transfer frame data from the first network by the transmission start time. . This is because the request frame data is transmitted in the request process so that all transfer frame data can be transmitted in the order determined in the schedule data. That is, in S580, whether or not such a normal operation is performed in the data transfer system 1 is indirectly determined based on the above determination.

  When it is determined that there is no transfer frame data that could not be received by the transmission start time (S580: No), the transfer process is terminated. On the other hand, if it is determined that there is transfer frame data that could not be received by the transmission start time (S580: Yes), the schedule data transmission necessity information corresponding to the transfer frame data that could not be received by the transmission start time is The value is changed from “required” to a value indicating “unnecessary” (S590), and the transfer process is completed. Incidentally, if the transmission necessity information is already “unnecessary” in S590, nothing is done here.

  The reason for performing the process of S590 is to reduce the processing load on the CPU 5 by suppressing the unnecessary transmission of the requested frame data. However, the transfer frame data may not be transmitted due to a temporary failure. Therefore, the data transfer apparatus 2 may be configured to restart the transmission of the requested frame data by resetting the transmission necessity information set to “unnecessary” to “necessary” after a predetermined time has elapsed. Further, the transmission necessity information may be changed from “required” to “unnecessary” when the reception has failed continuously for a predetermined number of times without being changed due to a single reception failure.

  As described above, in the present embodiment, the above-described object is achieved by the request processing and transfer processing executed by the CPU 5 of the data transfer device 2 and the response processing executed by the CPU of the node constituting the first network. Can reach. This is because the data transfer device 2 controls when the transfer frame data is transmitted to the nodes belonging to the first network.

  In other words, the data transfer device 2 transmits the schedule data information to the node that transmits the transfer frame data by the request frame data. Therefore, the node belonging to the first network can transmit the transfer frame data according to the schedule data used by the FlexRay while communicating by the CAN. Therefore, when transferring the transfer frame data from the CAN to the FlexRay, the control unit 3 can shorten the storage time of the transfer frame data. As a result, the capacity of the RAM 8 can be reduced.

  Another effect of the present embodiment is a reduction in the bus load of the first bus group B1. In the prior art, a large amount of transfer frame data that is not immediately transferred may be transmitted from the transfer source node, which may increase the bus load excessively. On the other hand, in this embodiment, the transfer frame data is periodically transmitted according to the schedule data from the transfer source node in an amount to be transferred, so that the bus load is excessive as in the prior art. There is no going up.

  The embodiment of the present invention is not limited to this example. The communication protocol may be another event-driven type instead of CAN. Further, instead of FlexRay, another time trigger type may be used. Further, the data transfer device 2 and each node may be configured so that each step of request processing, response processing, or transfer processing is realized by hardware. In this case, each step can be processed quickly.

  Finally, the correspondence between each means described in the claims and the embodiment will be described. However, the description of the obvious ones is omitted. The determining means is realized by S320 and S330 of request processing, and the requesting means is realized by S340 and S345 of request processing. The prohibiting means is realized by S590 of the transfer process, and the predicting means is realized by S303, S307, and S310 of the request processes.

1 is a block diagram showing a schematic configuration of a data transfer system 1 to which the present invention is applied. It is a block diagram which shows schematic structure of the node which belongs to a 1st network. 4 is a flowchart showing a request process executed by a CPU 5 of the data transfer apparatus 2. It is a figure showing schedule data. It is a flowchart showing the response process which CPU of the node which comprises a 1st network performs. 4 is a flowchart showing a transfer process executed by a CPU 5 of the data transfer apparatus 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Data transfer system, 2 ... Data transfer apparatus, 3, 1113 ... Control part, 5, 1115 ... CPU, 7, 1117 ... ROM, 8, 1118 ... RAM, 9 ... NVRAM, 11, 12, 21, 22, 1110 ... Communication unit, 111, 113, 115, 121, 123, 125, 211, 213, 215, 221, 223, 225 ... node, 110, 120, 210, 220 ... bus load measurement unit, B1 ... first bus group, B2 ... second bus group, B11, B12, B21, B22 ... bus

Claims (6)

Predetermined transfer target frame data connected to a first network that transmits and receives frame data using an event-driven communication protocol and a second network that transmits and receives frame data using a time-triggered communication protocol A data transfer device for transferring from the first network to the second network;
A node that is provided in the first network and executes transmission / reception of frame data according to the event-driven communication protocol;
A data transfer system comprising:
The time-triggered communication protocol is a communication protocol determined to transmit each frame data to the second network at a specified time according to a predetermined schedule,
The data transfer device
First communication means capable of transmitting and receiving frame data to and from the first network;
Second communication means capable of transmitting frame data to the second network;
Obtaining information as to which frame data of the frame data predetermined in the schedule is transmitted through the second network, and collating the obtained information with the schedule Determining means for determining whether or not the current time is a time before a transmission start time determined by the time-triggered communication protocol with respect to the frame data to be transferred;
When the determination unit determines that the current time is a time before a transmission start time determined by the time-triggered communication protocol with respect to the frame data to be transferred, the transfer target Request frame data for requesting the frame data, and the generated request frame data toward the node in the first network that can transmit the frame data to be transferred to the data transfer apparatus. Request means for causing the first communication means to transmit,
With
When receiving the request frame data, the node is configured to transmit the frame data to be transferred to the data transfer device via the first network in accordance with the request content of the request frame data.
The second communication means transmits the frame data to be transferred received by the first communication means through the first network to the second network at a specified time according to the schedule. system. The determination means and the request means are configured to repeatedly operate,
The data transfer device
If the first communication means does not receive the frame data to be transferred requested by the request frame data within a predetermined time after transmitting the request frame data, the first communication means 2. The data according to claim 1, further comprising prohibiting means capable of causing the requesting means to prohibit generation of the request frame data for requesting the frame data to be transferred that has not been received. Transfer system. The requesting means stores waiting time information in the request frame data to be generated,
When the node receives the request frame data in which the waiting time information is stored, the node is requested by the request frame data after the waiting time indicated by the request frame data from the time when the request frame data is received. The data transfer system according to claim 1 or 2, wherein the frame data to be transferred is transmitted to the data transfer device. The data transfer device
A delay that is a time from when the request means transmits the request frame data to when the second communication means can transmit the frame data to be transferred corresponding to the request frame data to the second network. With a prediction means to predict time,
The determination unit is configured to set the predetermined time to the delay time predicted by the prediction unit and to determine whether or not the current time is a time that is a predetermined time before the transmission start time. The data transfer system according to any one of claims 1 to 3, wherein: The said prediction means is provided with the network load measurement means which measures the load of said 1st network, and predicts the said delay time based on the measurement result of the said network load measurement means. Data transfer system. The data transfer device includes a CPU and a program storage unit that stores a program executed by the CPU.
The CPU realizes functions as the determination unit, the request unit, and the prediction unit by executing a program stored in the program storage unit,
The said program is comprised so that the said CPU can perform the process which measures the processing load of the said CPU and estimates the said delay time based on the measurement result of the said processing load. The data transfer system according to claim 4 or 5.

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