JP2006319759A - Gateway device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gateway device which can effectively relay communication frames within a limited time, even under the condition where the relayed amount of the communication frames is large. <P>SOLUTION: In the vehicle-mounted gateway device in which a plurality of networks are formed by connecting a plurality of control units using communication lines, and receiving processing, and transmitting processing of the communication frames are performed connecting the plurality of networks, the gateway device can be provided which includes a receiving means which receives the receiving frames, and stores in a communication frame buffer; an actual receiving processing time measuring means which measures the actual processing time of receiving and storing of the communication frames by the receiving means; and a transmission processing possible time calculation means which calculates transmission processing possible time, in which transmission processing is executable based on the real receiving processing time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gateway apparatus in which a plurality of networks in which a plurality of control units are connected by communication lines are formed, and the plurality of networks are connected to perform communication frame reception processing and transmission processing.

  For example, as a large number of control units that electronically control on-board equipment are adopted in a vehicle, there is an increasing demand for sharing data among the control units and performing distributed control and cooperative control in each control unit. For example, in a vehicle, each control unit is networked according to the classification of body systems such as seats and doors, power train systems such as engines and electronic throttles, and multimedia systems such as navigation devices, VICS, and ETC. Are being considered to be connected via a gateway device capable of relaying communication frames as data.

  When relaying communication frames via this gateway device, if the gateway device operates communication frame relay processing at regular intervals and the processing time is specified, the processing time based on the maximum received amount of communication frames within a unit time Is calculated, and within the time obtained by subtracting the reception processing time from the communication frame processing time, the transmittable time of the relayed communication frame is calculated to determine the communication frame relay amount.

JP 2000-124941 A

  As shown in FIG. 5, in the conventional communication frame relay processing, if the communication frame relay processing operates at a cycle of, for example, 5 msec and the communication frame transmission / reception processing time is specified to be, for example, 0.5 msec, Based on the network traffic, the communication frame reception processing times TRn and TRn + 1 are first defined as 0.3 msec, for example. The communication frame transmission processing times TSn and TSn + 1 are fixed times for the communication frame reception processing transmission processing, such as 0.2 msec obtained by subtracting the communication frame reception processing times TRn and TRn + 1 from the communication frame transmission / reception processing time 0.5 msec. A frame is assigned.

  In this case, in the communication frame transmission / reception process of the nth round, even if the communication frame reception amount is small and the actual communication frame reception processing time is as short as about 0.1 msec, the data transmission processing time TSn remains 0.2 msec. Therefore, even if the data to be transmitted is 0.2 msec or more, it is not possible to transmit all the communication frames to be transmitted within the communication frame transmission / reception process of the nth round. Communication frames that could not be transmitted must be transmitted in the next (n + 1) th communication frame transmission / reception process.

  However, even in the communication frame transmission / reception processing of the (n + 1) th round, if there are more than 0.2 msec of communication frames to be transmitted, further communication frame transmissions are left.

  In such a situation where the relay amount of the communication frame is small, it does not take a long time to receive and transmit the communication frame. However, in a situation where the amount of relay communication frame is large, the communication frame of the next cycle after receiving the communication frame In the relay process, the communication frame that could not be transmitted in the previous process must be transmitted, and the time taken from the reception to the transmission of the communication frame is increased. As a result, the gateway device and the operation of the network connected to the gateway device May also affect.

  With the above problem as a background, an object of the present invention is to provide a gateway device that can relay a communication frame efficiently within a limited time even in a situation where the communication frame relay amount is large.

Means for Solving the Problems and Effects of the Invention

  The present invention provides a gateway device for solving the above problems. That is, according to the first aspect of the present invention, in the gateway device in which a plurality of networks in which a plurality of control units are connected by communication lines are formed and the plurality of networks are connected to perform communication frame reception processing and transmission processing, Is received and stored in the communication frame buffer, the actual reception processing time measuring means for measuring the actual reception processing time of receiving and storing the communication frame by the receiving means, and the transmission processing is executed based on the actual reception processing time A transmission processable time calculating means for calculating a possible transmission processable time, and configured as a gateway device.

  In the prior art of FIG. 5, even if the actual reception processing time is 0.2 msec out of the 0.3 msec processing time allocated to the reception processing, the remaining 0.1 msec cannot be diverted to the transmission processing. However, in the configuration of the present invention, the communication frame transmission amount can be increased when the communication frame reception amount is small, and the communication frame transmission amount can be decreased when the communication frame reception amount is large, so that the communication frame can be relayed efficiently. It becomes possible.

  According to the second aspect, the reception process and the transmission process in the gateway device of the present invention can be configured to be repeatedly executed at a predetermined cycle.

  In general, the gateway apparatus often performs various processes periodically. In order to reduce the overall processing load, it is desirable that the processing time of these processes be short. Since the present invention is configured to calculate the transmission processable time during which the transmission process can be performed based on the actual reception processing time, the data can be relayed efficiently, and even if it is repeatedly executed at a predetermined cycle, the entire process An increase in processing load can be suppressed.

  According to the third aspect, it is possible to adopt a configuration in which the reception process and the transmission process in the gateway device of the present invention are repeatedly performed within a predetermined constraint time.

  From the viewpoint of the processing load of the gateway device, the reception process and the transmission process for relaying the communication frame may have to be performed within a predetermined constraint time. With the configuration of the present invention, it is possible to relay a communication frame efficiently within a limited time, so that it is possible to suppress an increase in the overall processing load even if it is repeatedly executed at a predetermined period.

  According to claim 4, the actual reception processing time measuring means in the gateway device of the present invention can be configured to calculate the actual reception processing time based on the reception and storage processing time per frame of the communication frame. .

  The reception processing time per frame of communication frames is within a certain range although it varies depending on the frame length. With the above-described configuration, it is not necessary to measure the reception processing time of all communication frames in the reception process, so that it is possible to reduce the processing load of the reception process.

  According to the fifth aspect, the transmission processable time calculating means in the gateway device of the present invention can be configured such that the transmission processable time is obtained by subtracting the actual reception processing time from the predetermined constraint time.

  With the above configuration, the communication frame transmission amount can be increased when the communication frame reception amount is small, and the communication frame transmission amount can be decreased when the communication frame reception amount is large. Is possible.

  According to claim 6, the gateway device of the present invention has map data defining the relationship between the actual reception processing time and the transmission processable time, and the transmission processable time calculating means calculates the transmission processable time from the map data. The structure to calculate can be taken.

  With the above configuration, it is possible to calculate the transmission processable time only by the map data reference process, and it is not necessary to perform an arithmetic process using a calculation formula, so the processing load of the transmission processable time calculation process can be reduced. It becomes possible.

  According to the seventh aspect, the map data in the gateway device of the present invention can take a configuration in which the relationship between the number of received communication frames and the number of transmittable communication frames is defined.

  The reception processing time and transmission processing time per frame of the communication frame are within a certain range although they vary depending on the frame length. Therefore, the actual reception processing time of all frames in the reception processing can be measured as the number of received frames instead of time. With the above configuration, it is not necessary to actually measure or convert the communication frame reception processing time, and the processing load of the communication frame reception processing can be reduced. Furthermore, since the transmission processable time can also be calculated from the map data as the number of frames that can be transmitted, it is not necessary to perform a calculation process using a calculation formula, so the processing load of the transmission processable time calculation process can be reduced. Become.

  FIG. 4 shows an example in which the reception process and the transmission process of the configuration of the present invention are repeatedly executed at a predetermined cycle of, for example, 5 msec, and are performed within a certain time, for example, a predetermined constraint time such as 0.5 msec. In the n-th round process, the actual reception processing time TRn of the reception process is about 0.22 msec. In the prior art of FIG. 5, since a fixed time frame of 0.3 msec is set for the reception process, only 0.2 msec can be assigned for the transmission process, but in the configuration of the present invention of FIG. 4, 0.28 msec is the transmission process. Since it can be assigned to TSn, more communication frames than before can be transmitted. In other words, conventionally, a communication frame exceeding 0.2 msec could not be transmitted and had to be transmitted in the next n + 1 round processing, but in the present invention, a communication frame corresponding to 0.08 msec was transmitted for the nth time. Therefore, it is possible to improve the processing efficiency of the gateway device and the network connected to the gateway device.

  In the (n + 1) -th round processing executed 5 msec after the n-th round processing, the actual reception processing time TRn + 1 of the reception processing is about 0.25 msec. 05 msec can be used and more frames can be transmitted.

  Similarly, in the (n + 2) -th round processing executed 5 msec after the (n + 1) -th round processing, since the actual reception processing time TRn + 2 of the reception processing is about 0.17 msec, the communication frame transmission processing time TSn + 2 is 0.33 msec. Can be used, and about 1.5 times as many frames as before can be transmitted.

  Note that the maximum actual reception processing time is set to 0, for example, based on physical restrictions such as the communication speed of the communication bus and the minimum / maximum length of the communication frame, and time restrictions such as a processing timing of a 5 ms cycle determined by the processing configuration of the gateway device. .3 msec can be set. The total transmission / reception processing time is set to, for example, 0.5 ms so that at least one communication frame can be transmitted by the cyclic processing even when the reception processing of the maximum time theoretically occurs continuously. Has been.

  The purpose is to provide a gateway device that can relay data efficiently within a limited time even when there is a large amount of relay data. This was realized by a configuration in which the amount of processing was dynamically variable, such as reducing the amount of data transmission at many timings.

  Hereinafter, embodiments of the present invention will be described based on an example in which the gateway device of the present invention is applied to a vehicle. The scope of application of the gateway device of the present invention is not limited to a vehicle, and can be applied to, for example, a network communication device.

  FIG. 1 is a block diagram showing the overall configuration of the gateway device and peripheral network of the present invention. Various control units that electronically control on-vehicle equipment form a network, and are connected to each other via a communication bus and further a gateway device.

  In the example of FIG. 1, a body system network is configured on the communication bus 1, and an ECU-A that controls the door lock and an ECU-B that adjusts the position of the seat are connected. In addition, a powertrain network is configured on the communication bus-2, and an ECU-C that controls the engine, an ECU-D that controls the transmission, and an ECU-E that controls the brake are connected.

  As shown in FIG. 2, the gateway device 10 includes a first communication I / F 16 and a second communication I / F 17 which are receiving means of the present invention to which the communication bus-1 and the communication bus-2 are connected, and a communication bus- 1 and the MPU 11 that controls data transmission between the communication buses 2, and the MPU 11 executes various processes performed by the gateway device 10. Connected to the MPU 11 which is a reception processing time measuring means and a transmission processable time calculating means of the present invention are a RAM 12, a flash memory 13 and a ROM 14 which store data or programs used when executing various processes including a data transmission process. Has been.

  The ROM 14 stores, for example, a main program 14p for executing various processes performed by the gateway device 10 and device identification information 14b such as a device number of the gateway device 10. The flash memory 13 stores, for example, a processing program 13p for executing various processes performed by the gateway device 10. The MPU 11 executes the main program 14p stored in the ROM 14, and reads and executes a necessary processing program 13p from the flash memory 13. The processing program stored in the flash memory 13 can be updated by the MPU 11. The update process is performed by an input operation unit (not shown) such as a switch provided on the instrument panel, for example.

  Data necessary for executing various processes is read from the RAM 12, the flash memory 13, and the ROM 14 by the MPU 11. The processing result is stored in the RAM 12 or the flash memory 13 by the MPU 11. For example, an address table including addresses of ECU-A to ECU-E is stored in the RAM 12, and a filtering policy such as a transmission source and / or a transmission destination that blocks data transfer is stored in the flash memory 13. The MPU 11 performs communication frame relay processing with reference to the address table and the filtering policy. It is also possible to use only the flash memory 13 without using the RAM 12.

  The communication protocols used in the communication bus-1 and the communication bus-2 are known token passing systems, CSMA / CD (Carrier Sense Multiple Access with Collision Detection) systems, and TDMA (Time Division Multiple Access: Various known protocols such as a time division multiple access method may be employed. It is also possible to employ different communication protocols for each network. The first communication I / F 16 and the second communication I / F 17 have a circuit configuration including known communication LSIs 16a and 17a corresponding to the communication protocols of the respective networks.

Reception of a communication frame from the communication bus 1 or 2 is performed using at least one of the following (1) or (2).
(1) The communication frame received from the communication bus 1 or 2 is stored in the buffers 16b and 17b that are included in the communication I / F 16 and the second communication I / F 17 and configured by a RAM or the like. The received communication frame is stored in each buffer by a method of directly transferring the communication frame from the communication LSIs 16a and 17a to each buffer, or by a control program operated by a CPU (not shown) that performs overall control of the communication I / Fs 16 and 17. Any method of transferring communication frames from the LSIs 16a and 17a to the buffers 16b and 17b may be used.
(2) The communication frame received from the communication bus 1 or 2 is fetched from the communication I / F 16 or the second communication I / F 17 by the communication driver program included in the main program 14p and stored in the buffer 12a whose area is secured in the RAM 12. accumulate.
When a communication frame is received from the communication bus 1 or 2, a communication frame reception flag indicating that the communication frame has been received is set. An area for the communication frame reception flag is secured for each communication frame.

  The number of communication buses to be connected is not limited, and a safety network such as a multimedia system and an air bag may be included in the configuration in addition to a power train system and a body system network. In this case, a communication I / F corresponding to the communication protocol of the added network is also added.

  As shown in FIG. 6, the communication frame has a header field and a data field, and a data body is written in the data field. The header field includes device identification information of ECU-A to ECU-E, an ID indicating the meaning of the communication frame such as the vehicle speed and the engine speed, and a data length code (DLC) indicating the length of the data body. ) And

  With the configuration as described above, the gateway device 10 stores the communication frame received from the communication bus-1 through the first communication I / F 16 in the frame buffer and transmits it to the communication bus-2 via the second communication I / F17. That is, it relays. For example, the communication frame from ECU-A is relayed to ECU-C to ECU-E. Moreover, you may relay the communication frame from ECU-A to ECU-B connected to the same communication bus-1. Conversely, the communication frame from ECU-E connected to communication bus-2 is relayed to ECU-A and ECU-B connected to communication bus-1. Similarly, the communication frame from ECU-E may be relayed to ECU-C connected to the same communication bus-1.

  FIG. 3 shows a flowchart of the main process stored in the ROM 14 of the gateway apparatus 10 and included in the main program 14p executed by the MPU 11. The main process is executed at a constant cycle such as a 5 msec cycle. When the start timing of the main process is generated by a timer or the like and the start timing of the main process is reached (S1: Yes), for example, other processes other than the communication frame transmission / reception process (S2), the communication frame reception process, etc. (S3) and communication frame transmission processing (S4) are executed in this order.

  FIG. 8 is a flowchart illustrating the details of the communication frame reception process shown in step S3 of FIG. First, a reception frame counter that counts the number of communication frames received in the current data reception process is initialized, that is, cleared to zero (S11).

  When a communication frame is received, that is, when a communication frame is accumulated in the buffers 16b, 17b or the buffer 12a (S12: Yes), a frame buffer in which an area is secured in the RAM 12 for each ID of the communication frame. (S13). Then, the corresponding communication frame reception flag is cleared. At this time, the contents of the buffers 16b and 17b or the buffer 12a may be cleared to zero.

FIG. 7 shows an example of the frame buffer. Any of the following (1) to (4) may be used for the configuration of the frame buffer.
(1) The area number of the data area corresponds to the ID of the communication frame. That is, the contents of the data body whose communication frame ID is 0 are stored in DATA0, and the contents of the data body whose communication frame ID is n are all stored in DATAn.
(2) The received communication frame is divided into bytes, for example, and stored in the data area. For example, if the data body of the communication frame is 8 bytes, m in the data area in FIG. 7 is 7, and 1 byte is stored in 0 to 7 in the data area. In this case, there may be one flag area. That is, the frame buffer has an area for each ID.
(3) The received communication frame is converted into the format of the destination communication frame and stored in the data area. You may store collectively for every ID of the communication frame to transmit, or you may divide and store 1 byte at a time.
(4) A well-known FIFO (First-In, First-Out) buffer suitable for performing relay processing in the order of reception of communication frames, instead of securing a frame buffer for each communication frame ID. Alternatively, a well-known LIFO (Last-In, First-Out) buffer suitable for performing relay processing in the reverse order of the communication frame reception order may be used. In this case, both the ID and data of the communication frame are stored.

  When the received communication frame is stored in the frame buffer, the content of the corresponding flag area is set to 1 indicating the presence of reception data, that is, the presence of a transmission request, and the reception frame counter is incremented (S14). When all the communication frames stored in the buffers 16b and 17b or the buffer 12a are extracted (S15: No), the number of communication frames that can be transmitted is calculated (S16).

  Whether or not all received communication frames are stored in the frame buffer is determined when all the communication frames stored in the buffers 16b and 17b or the buffer 12a are fetched, that is, the above-described communication frame reception flag is set. If all are cleared, it is determined that all received communication frames are stored in the frame buffer. When the contents of the buffers 16b, 17b or the buffer 12a are cleared to zero when stored in the frame buffer, all the communication frames are stored in the frame buffer as long as the contents of the buffers 16b, 17b or the buffer 12a are all cleared to zero. You may judge.

  There is a predetermined relationship between the number of received communication frames and the number of communication frames that can be transmitted, and is stored in the ROM 14, RAM 12, or flash memory 13 as map data as shown in FIG. The reception processing time per frame of the communication frame can be obtained in advance by the performance of peripheral circuits such as the MPU 11 and the communication I / Fs 16 and 17. The actual reception processing time can be obtained by multiplying the reception processing time per frame of the communication frame by the number of received communication frames. Therefore, the time during which the communication frame can be transmitted is obtained by subtracting the actual reception processing time from a predetermined constraint time such as 0.5 msec as shown in FIG. Here, since the transmission processing time per frame can also be obtained in advance by the performance of the MPU 11, the transmission processing time of the communication frame can be replaced with the number of communication frames that can be transmitted. In addition, by storing the number of received communication frames and the number of communication frames that can be transmitted as map data, it is possible to shorten the calculation processing time. Therefore, the number of communication frames that can be transmitted can be obtained from the number of communication frames received with reference to the map data.

  FIG. 9 is a flowchart for explaining details of the communication frame transmission process shown in step S4 of FIG. It is checked whether there is a transmission request by referring to the flag area of the frame buffer indicated by the pointer content, that is, the transmission request flag. When the content of the flag area is 1 and there is a transmission request (S21: Yes), the communication frame stored in the data area is transmitted (S22). Then, the contents of the flag area are cleared to zero (S23), and the number of transmittable frames is decremented (S24).

  Next, the contents of the pointer are incremented to the position of the next frame buffer (S25), and the processes from step S21 to S25 are repeated until the number of transmittable frames becomes zero. On the other hand, if there is no transmission request (S21: No), the contents of the pointer are incremented to check whether there is a transmission request for the next frame buffer (S25 → S21).

  The pointer indicates the position of the frame buffer waiting for transmission, that is, the address, of the data body or individual data indicated by the data ID stored in the frame buffer. The initial value of the pointer is the start address of the frame buffer. If the pointer is incremented when the content of the pointer is the end address of the frame buffer, the pointer returns to the start address of the frame buffer.

  When a FIFO or LIFO is used as the frame buffer, if there is no transmission request in the frame buffer indicated by the pointer, no data is stored in the subsequent frame buffer, so even if the pointer contents are returned to the start address of the frame buffer. Good.

  As a method for determining the presence or absence of a transmission request, a transmission queue described below may be used in addition to the method using the pointer described above. When a communication frame is stored in the frame buffer, instead of setting a flag indicating that there is reception data, that is, a transmission request, the position of the frame buffer indicated by the ID (1, 2,..., N,... M) The information is stored in a FIFO transmission queue whose area is secured in the RAM 12, and the transmission queue counter is incremented. The maximum value of the transmission queue counter is m. For example, when the transmission queue counter value is 1, since one transmission queue is already stored, the position information of the frame buffer is stored in the second area of the transmission queue, and the transmission queue counter value is updated to 2. The

  At the time of communication frame transmission processing, the value of the transmission queue counter is first referred to. If the value is not zero, the content at the head of the transmission queue area is referred to, and the communication frame is determined based on the stored position information of the frame buffer. Send. Then, the transmission queue counter is decremented, and the content of the transmission queue is shifted by one in the head direction of the transmission queue area. For example, if the transmission queue counter value is 3, that is, if there are three transmission queues, after transmitting a communication frame corresponding to the contents of the first area of the transmission queue, the transmission queue counter value is set to 2, and the second transmission queue counter value Is moved to the first area of the transmission queue, and the content of the third area of the transmission queue is moved to the second area of the transmission queue. At this time, the third area of the transmission queue may be cleared to zero. When the transmission queue is used, it is not necessary to check whether or not there is a transmission request for the entire frame buffer, and frame transmission can be performed efficiently.

  In addition, a known ring buffer structure or list structure may be used instead of the data structure of the transmission order FIFO such as the first and second statically as the transmission queue. In this case, the position information of the transmission queue in which the position information of the frame buffer to be transmitted next is stored as a pointer secured in a separate area from the transmission queue. If the transmission queue counter is not zero, that is, there is an unrelayed communication frame, the communication frame is transmitted based on the position information of the frame buffer stored in the transmission queue corresponding to the pointer, and then the pointer is updated. To do. At this time, if the ring buffer configuration is used, the pointer is incremented to the position of the next transmission queue. When the pointer value reaches the end of the transmission queue, that is, the ring buffer, it is set at the top buffer position. In the case of a list structure, the pointer value is a list position including the next transmission queue in the data structure. In any structure, as a fail safe, when there is no transmission queue, the pointer may be set to an initial value which is the head position of the buffer or the list.

If frame buffers without transmission requests continue, the time limit of communication frame transmission processing may be exceeded only by determining whether there is a transmission request. In this case, the processing time when there is no transmission request from step S21: No → S25 → S26 can be obtained in advance from the performance of the MPU 11, for example, “processing time when there is no transmission request × 3 = processing when there is a transmission request” Since a relationship such as “time” can be defined, the following processing may be added between step S21: No and S25.
(1) Increment the no transmission request occurrence counter.
(2) When the transmission request absence occurrence counter reaches a predetermined value such as 3, for example, the number of transmittable frames is decremented and the transmission request no occurrence counter is cleared to zero.

  The ROM 14, RAM 12 or flash memory 13 stores in advance the reception processing time per frame of communication frames, and after receiving all communication frames, the product of the reception frame counter and the reception processing time per frame is the actual reception processing. The transmission processing time may be a time obtained by subtracting the actual reception processing time from the predetermined constraint time of 0.5 msec. In the communication frame transmission process, every time one communication frame is sent, the transmission processing time per frame is subtracted from the transmission processable time, and the reduced value is larger than the value of the transmission processing time per frame. Send the next communication frame.

  Further, the relationship between the actual reception processing time and the transmission processing available time may be stored as map data, and the transmission processing available time may be obtained from the map data based on the actual reception processing time calculated as described above.

  In addition, since the MPU 11 has a built-in free run counter for generating a reference time inside the MPU 11, the communication frame reception process starts from the free run counter value at the end of the communication frame reception process (S16) (S11). ) Minus the free-run counter value may be used as the actual reception processing time. Then, the transmission processable time may be obtained by subtracting the actual reception processing time from the predetermined constraint time of 0.5 msec. In the communication frame transmission process, a value obtained by subtracting the free run counter value at the start of the communication frame transmission process from the free run counter value at the time of transmitting the communication frame is a free run corresponding to the transmission processing time per frame. If it is larger than the counter value, the next communication frame is transmitted.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

The block diagram which shows the structure of a gateway apparatus and a periphery network. The block diagram which shows the structure of a gateway apparatus. The flowchart explaining the outline of a main process. The figure which shows the time distribution of the communication frame reception process and communication frame transmission process by this invention. The figure which shows the time distribution of the communication frame reception process by the prior art, and a communication frame transmission process. The figure which shows an example of the data structure of a communication frame. The figure which shows an example of a structure of a frame buffer. The flowchart explaining a communication frame reception process. The flowchart explaining a communication frame transmission process. The figure which shows an example of a structure of map data.

Explanation of symbols

10 gateway device 11 MPU (reception processing time measuring means, transmission processing possible time calculating means)
12 RAM
13 Flash memory 14 ROM
16 1st communication I / F (reception means)
17 Second communication I / F (receiving means)

Claims (7)

In a gateway apparatus in which a plurality of networks in which a plurality of control units are connected by communication lines are formed, and the plurality of networks are connected to perform communication frame reception processing and transmission processing.
Receiving means for receiving the communication frame and storing it in a communication frame buffer;
Actual reception processing time measuring means for measuring the actual reception processing time of receiving and storing the communication frame by the receiving means;
A transmission processable time calculating means for calculating a transmission processable time during which the transmission process can be executed based on the actual reception processing time;
A gateway device comprising:   The gateway apparatus according to claim 1, wherein the reception process and the transmission process are repeatedly executed at a predetermined cycle.   The gateway apparatus according to claim 1, wherein the reception process and the transmission process are performed within a predetermined restriction time.   4. The gateway device according to claim 1, wherein the actual reception processing time measurement unit calculates the actual reception processing time based on reception and storage processing times per frame of the communication frame. 5.   5. The gateway device according to claim 1, wherein the transmission processable time calculating unit sets the transmission processable time as a value obtained by subtracting the actual reception processing time from the predetermined constraint time. 6. Having map data defining a relationship between the actual reception processing time and the transmission processable time;
The gateway apparatus according to claim 1, wherein the transmission processable time calculating unit calculates the transmission processable time from the map data. The gateway apparatus according to claim 6, wherein the map data defines a relationship between the number of received communication frames and the number of communication frames that can be transmitted.

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