WO2017006464A1

WO2017006464A1 - Communication apparatus, communication method, and communication program

Info

Publication number: WO2017006464A1
Application number: PCT/JP2015/069679
Authority: WO
Inventors: 嗣也大石
Original assignee: 三菱電機株式会社
Priority date: 2015-07-08
Filing date: 2015-07-08
Publication date: 2017-01-12
Also published as: TW201703478A

Abstract

A control apparatus (100) is included in a communication system that includes a plurality of control apparatuses and in which token passing is performed between the plurality of control apparatuses. A communication frame buffer (1003) stores a communication frame addressed to another control apparatus. A transmission-right determination unit (1002) determines a control apparatus currently having a transmission right among the plurality of control apparatuses. In the case where the control apparatus currently having the transmission right is the other control apparatus, and a communication frame addressed to a transmission-right having control apparatus that is the other control apparatus currently having the transmission right is stored in the communication frame buffer (1003), a frame transmission unit (1004) transmits, to the transmission-right having control apparatus, the communication frame stored in the communication frame buffer (1003) and addressed to the transmission-right having control apparatus.

Description

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMMUNICATION PROGRAM

The present invention relates to a communication system in which token passing is performed.

In the FA (Factor Automation) network system field, communication performed between a plurality of control devices compatible with full-duplex communication connected to a network is communication periodically performed every communication cycle (hereinafter referred to as periodic communication). ) And communication (hereinafter referred to as irregular communication) performed at each request.
As a method for controlling transmission between a plurality of control devices, there is a token passing method.

In the token passing method, tokens are sequentially delivered to each control device via the network, and only the control device that obtains the token has the transmission right of the communication frame, so that collision of communication frames can be avoided.

As an example of the FA network system using the token passing system, there is a CC-Link IE Field disclosed in Non-Patent Document 1.
In CC-Link IE Field, the amount of non-scheduled communication that can be transmitted (hereinafter referred to as the amount of non-scheduled communication) in order to realize the coexistence of scheduled and non-scheduled communication while ensuring the regularity of regular communication. Is limiting.
A link scan unit limiting method, which is one of the methods for limiting the irregular communication possible amount, will be described with reference to FIG.
The link scan unit restriction method is a method in which an irregular communication possible amount is determined while the token makes one round between the control devices (hereinafter referred to as one cycle).

FIG. 8 shows a communication sequence example between CC-Link IE Field control devices.
In the communication sequence example of FIG. 8, regular communication is performed between the control device (1) 1010 that is the master device and the control device (2) 1020, the control device (3) 1030, and the control device (4) 1040 that are slave devices. Is done.
In FIG. 8, it is assumed that the control device (3) 1030 and the control device (4) 1040 need irregular communication with the control device (2) 1020.
Further, in FIG. 8, it is assumed that the irregular communication possible amount is 1 (one communication frame).

S21: When the control device (1) 1010 holds the transmission right The control device (1) 1010 holding the transmission right communicates with the control device (2) 1020 to the control device (4) 1040 for regular communication. A periodic communication frame (request data) that is a frame is transmitted.
When the transmission of the regular communication frame is completed, the control device (1) 1010 transmits the token frame to the control device (2) 1020 to the control device (4) 1040.
The token frame is a communication frame for notifying the control device that holds the transmission right.
Here, it is assumed that the amount of irregular communication is notified in the token frame (n = 1 or n = 0 in FIG. 8).
In the token frame transmitted by the control device (1) 1010, it is notified that the control device (2) 1020 holds the transmission right.

S22: When the control device (2) 1020 holds the transmission right The control device (2) 1020 transmits a periodic communication frame (response data) to the control device (1) 1010.
The regular communication frame (response data) is a response to the regular communication frame (request data) from the control device (1) 1010.
Since each of control device (1) 1010, control device (3) 1030, and control device (4) 1040 does not hold a transmission right, it does not transmit a communication frame.
When the transmission of the regular communication frame is completed, the control device (2) transmits the token frame to the control device (1) 1010, the control device (3) 1030, and the control device (4) 1040.
In the token frame transmitted by the control device (2) 1020, it is notified that the control device (3) 1030 holds the transmission right.

S23: When the control device (3) 1030 holds the transmission right The control device (3) 1030 transmits a periodic communication frame (response data) to the control device (1) 1010.
Also, the control device (3) 1030 transmits an irregular communication frame (request data), which is a communication frame for irregular communication, to the control device (2) 1020.
Since the control device (3) 1030 transmits an irregular communication frame to the control device (2) 1020, the possible amount of irregular communication amount becomes 0 (n = 0).
Since each of control device (1) 1010, control device (2) 1020, and control device (4) 1040 does not hold a transmission right, it does not transmit a communication frame.
When the transmission of the regular communication frame and the irregular communication frame is completed, the control device (3) 1030 transmits the token frame to the control device (1) 1010, the control device (2) 1020, and the control device (4) 1040.
In the token frame transmitted by the control device (3) 1030, it is notified that the control device (4) 1040 holds the transmission right.
Further, in the token frame transmitted by the control device (3) 1030, it is notified that the irregular communication possible amount has been exhausted.

S24: When the control device (4) 1040 holds the transmission right The control device (4) 1040 transmits a periodic communication frame (response data) to the control device (1) 1010.
Since the control device (3) 1030 transmits the irregular communication frame to the control device (2) 1020 in S23, there is no remaining irregular communication possible amount, and the control device (4) 1040 transmits the irregular communication frame. I can't.
Since each of control device (1) 1010, control device (2) 1020, and control device (3) 1030 does not hold a transmission right, it does not transmit a communication frame.
When the transmission of the regular communication frame is completed, the control device (4) 1040 transmits the token frame to the control device (1) 1010, the control device (2) 1020, and the control device (3) 1030.
In the token frame transmitted by the control device (4) 1040, it is notified that the control device (1) 1010 holds the transmission right.

S25: Repeat The above-described S21 to S24 are repeated.

As described above, the non-patent document 1 defines a non-periodic communicable amount in order to realize a mixture of regular communication and irregular communication while performing regular communication by the token passing method.
Therefore, the technique of Non-Patent Document 1 has a problem that even when there is a request for irregular communication exceeding the irregular communication possible amount, irregular communication cannot be performed, and transmission efficiency of irregular communication decreases. .
Furthermore, since the control device holding the transmission right performs irregular communication when performing regular communication, the amount of communication from the control device holding the transmission right increases, and the transmission efficiency of the periodic communication also decreases. There is.

The main object of the present invention is to solve the above-mentioned problems, and it is a main object of the present invention to increase the efficiency of regular communication and irregular communication by increasing opportunities for irregular communication.

The communication device according to the present invention is
A communication device included in a communication system including a plurality of communication devices and performing token passing between the plurality of communication devices,
A communication frame buffer for storing communication frames addressed to other communication devices;
A transmission right determination unit for determining a communication device that currently holds the transmission right among the plurality of communication devices;
When the communication device that currently holds the transmission right is another communication device, and the communication frame addressed to the transmission right holding communication device that is another communication device that currently holds the transmission right is stored in the communication frame buffer, A frame transmission unit configured to transmit a communication frame addressed to the transmission right holding communication device stored in the communication frame buffer to the transmission right holding communication device.

In the present invention, when another communication device holds the transmission right, a communication frame addressed to another communication device holding the transmission right can be transmitted to the other communication device.
For this reason, according to this invention, the opportunity of irregular transmission can be increased and, therefore, the transmission efficiency of regular communication and irregular communication can be improved.

1 is a diagram illustrating a configuration example of a communication system according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a functional module configuration example of the control device according to the first embodiment. FIG. 5 is a diagram illustrating an operation example of a control device that holds a transmission right according to the first embodiment. FIG. 3 is a diagram illustrating an operation example of a control device that does not hold a transmission right according to the first embodiment. FIG. 3 is a flowchart showing an operation example of the control device according to the first embodiment. FIG. 3 is a diagram showing an example of a communication sequence between control devices according to the first embodiment. FIG. 3 is a diagram illustrating a hardware configuration example of a control device according to the first embodiment. The figure which shows the example of a communication sequence between the conventional control apparatuses.

Embodiment 1 FIG.
*** Explanation of configuration ***
FIG. 1 shows a configuration example of a communication system according to the present embodiment.

The communication system according to the present embodiment includes a star topology in which a control device (1) 101, a control device (2) 102, a control device (3) 103, and a control device (4) 104 are connected by a switching hub. Have
Control device (1) 101, control device (2) 102, control device (3) 103, and control device (4) 104 are each connected to a switching hub via a transmission line for full-duplex communication.
The control device (1) 101 is a master device.
The control device (2) 102, the control device (3) 103, and the control device (4) 104 are slave devices.
Token passing is performed between the control device (1) 101, the control device (2) 102, the control device (3) 103, and the control device (4) 104.
The control device (1) 101, the control device (2) 102, the control device (3) 103, and the control device (4) 104 each correspond to an example of a communication device.
If it is not necessary to distinguish between the control device (1) 101, the control device (2) 102, the control device (3) 103, and the control device (4) 104, the control device (1) 101 and the control device (2) 102, the control device (3) 103, and the control device (4) 104 are collectively referred to as a control device 100.

FIG. 2 shows a functional module configuration example of the control device 100 according to the present embodiment.

The frame receiving unit 1001 receives a communication frame from another control device 100.
More specifically, the frame receiving unit 1001 receives regular communication frames, non-periodic communication frames, and token frames from other control devices 100.

The transmission right determination unit 1002 analyzes the token frame received by the frame reception unit 1001 and determines a control device that holds the current transmission right among the plurality of control devices 100.
Then, when the control device that holds the transmission right is another control device, the transmission right determination unit 1002 transmits another control device that holds the transmission right (hereinafter, another control device that holds the transmission right to the transmission right). (Referred to as holding control device) is notified to a communication frame buffer 1003 described later.
The transmission right holding control device corresponds to an example of a transmission right holding communication device.
When the control apparatus that holds the transmission right is the own apparatus, the transmission right determination unit 1002 instructs the communication frame buffer 1003 to transmit the periodic communication frame.
The processing performed by the transmission right determination unit 1002 corresponds to an example of transmission right determination processing.

The communication frame buffer 1003 stores communication frames addressed to other control devices 100.
That is, the communication frame buffer 1003 stores regular communication frames and irregular communication frames addressed to other control devices 100.
Further, the communication frame buffer 1003 describes an irregular communication frame addressed to the transmission right holding control device when the irregular communication frame addressed to the transmission right holding control device notified from the transmission right determining unit 1002 is stored. The data is output to the frame transmission unit 1004.
Further, the communication frame buffer 1003 outputs the periodic communication frame to the frame transmitting unit 1004 when the transmission right determining unit 1002 is instructed to transmit the periodic communication frame.

When an irregular communication frame addressed to the transmission right holding control device is stored in the communication frame buffer 1003, the frame transmission unit 1004 stores the irregular communication frame addressed to the transmission right holding control device stored in the communication frame buffer 1003. Is transmitted to the transmission right control communication device.
That is, the frame transmission unit 1004 transmits the irregular communication frame addressed to the transmission right holding control apparatus output from the communication frame buffer 1003 to the transmission right holding control apparatus.
The frame transmitting unit 1004 transmits an irregular communication frame addressed to the transmission right holding control device to the transmission right holding control device in parallel with the transmission of the periodic communication frame based on the transmission right in the transmission right holding control device.
When a regular communication frame is output from the communication frame buffer 1003, the frame transmission unit 1004 transmits the regular communication frame to the destination of the regular communication frame.
The processing performed by the frame transmission unit 1004 corresponds to an example of frame transmission processing.

*** Explanation of operation ***
FIG. 3 shows an operation example of the control device (4) 104 when holding the transmission right.
That is, FIG. 3 shows an operation example of the control device (4) 104 when the transmission right determination unit 1002 determines that the transmission right is in the control device (4) 104 as a result of analyzing the token frame.

Since the transmission right is in the control device (4) 104, the transmission right determination unit 1002 determines to transmit the periodic communication frame, and instructs the communication frame buffer 1003 to transmit the periodic communication frame.
The communication frame buffer 1003 outputs a regular communication frame to the frame transmission unit 1004 based on an instruction from the transmission right determination unit 1002.
The frame transmission unit 1004 transmits the periodic communication frame output from the communication frame buffer 1003 to the destination of the periodic communication frame (in this case, the control device (1) 101 which is the master device).
Also, if the amount of irregular communication that can be performed in the current cycle remains and irregular communication is necessary, the transmission right determination unit 1002 instructs the communication frame buffer 1003 to transmit the irregular communication frame, and the communication frame buffer 1003. Outputs an irregular communication frame to the frame transmission unit 1004.
Then, the frame transmission unit 1004 transmits the irregular communication frame output from the communication frame buffer 1003 to the destination (in this case, the control device (2) 102 or the control device (3) 103).
As in this example, when the transmission right holding control apparatus transmits an irregular communication frame, the amount of irregular communication that can be performed in the current cycle is reduced.
Although FIG. 3 shows an operation example of the control device (4) 104, the same operation is performed in other control devices.

FIG. 4 shows an operation example of the control device (4) 104 when the transmission right is not held.
That is, FIG. 4 shows an operation example of the control device (4) 104 when it is determined that the transmission right is in a control device other than the control device (4) 104 as a result of the transmission right determination unit 1002 analyzing the token frame. .
In the following, it is assumed that the control device (2) 102 currently holds the transmission right.

Since the transmission right is in the control device (2) 102, the transmission right determination unit 1002 notifies the communication frame buffer 1003 of the control device (2) 102 as a transmission right holding control device.
The communication frame buffer 1003 outputs an irregular communication frame addressed to the control device (2) 102 to the frame transmission unit 1004 based on the notification from the transmission right determination unit 1002.
The frame transmission unit 1004 transmits the irregular communication frame addressed to the control device (2) 102 output from the communication frame buffer 1003 to the control device (2) 102.
Transmission of irregular communication frames from a control device other than the transmission right holding control device as in this example to the transmission right holding control device does not decrease the amount of irregular communication.
Although FIG. 4 shows an operation example of the control device (4) 104, the same operation is performed in other control devices.

FIG. 5 is a flowchart showing an operation procedure of the control device 100 according to the present embodiment.
The operation procedure illustrated in FIG. 5 corresponds to an example of a communication method and a communication program.

When the frame reception unit 1001 receives the token frame (YES in S101), the frame reception unit 1001 outputs the token frame to the transmission right determination unit 1002.
Then, the transmission right determination unit 1002 analyzes the token frame and determines whether or not the own apparatus holds the transmission right (S102).

When the own device holds the transmission right (YES in S102), the transmission right determination unit 1002 instructs the communication frame buffer 1003 to transmit the periodic communication frame.
The communication frame buffer 1003 outputs the regular communication frame to the frame transmission unit 1004, and the frame transmission unit 1004 transmits the regular communication frame (S103).
Further, the transmission right determination unit 1002 determines whether or not irregular communication is necessary (S104).
If irregular transmission is necessary (YES in S104), the transmission right determination unit 1002 notifies the communication frame buffer 1003 of the destination of irregular communication.
Then, the communication frame buffer 1003 outputs an irregular communication frame corresponding to the destination to the frame transmission unit 1004, and the frame transmission unit 1004 transmits the irregular communication frame to the destination (S105).
Also, the transmission right determination unit 1002 reduces the amount of irregular communication possible.
For example, the transmission right determination unit 1002 reduces the possible amount of irregular communication described in the token frame by one.
Further, the transmission right determination unit 1002 generates a token frame that grants the transmission right to the next control device 100 in the token assignment order, and the frame transmission unit 1004 transmits the token frame to all the control devices 100 (S107). .
Thereafter, the process returns to S101.

On the other hand, if the own device does not hold the transmission right in S102 (NO in S102), the transmission right determination unit 1002 notifies the communication frame buffer 1003 of the transmission right holding control device.
If an irregular communication frame addressed to the transmission right holding control device is not stored in the communication frame buffer 1003 (NO in S108), the process returns to S101.

On the other hand, if an irregular communication frame addressed to the transmission right holding control device is stored in the communication frame buffer 1003 (YES in S108), the communication frame buffer 1003 transmits an irregular communication frame addressed to the transmission right holding control device. Output to the unit 1004.
Then, the frame transmission unit 1004 transmits an irregular communication frame addressed to the transmission right holding control device to the transmission right holding control device (S109).
Thereafter, the process returns to S101.

FIG. 6 shows an example of a communication sequence between the control devices 100 according to the present embodiment.
In the control device (3) 103 and the control device (4) 104, it is assumed that irregular communication frames addressed to the control device (2) 102 are stored in the communication frame buffer 1003, respectively.

S11: When the control device (1) 101 holds the transmission right The control device (1) 101 holding the transmission right sends a periodic communication frame () to the control device (2) 102 to the control device (4) 104. Request data).
When the transmission of the regular communication frame is completed, the control device (1) 101 transmits the token frame to the control device (2) 102 to the control device (4) 104.
In the token frame transmitted by the control device (1) 101, it is notified that the control device (2) 102 holds the transmission right.

S12: When the control device (2) 102 holds the transmission right The control device (2) 102 transmits a periodic communication frame (response data) to the control device (1) 101.
The regular communication frame (response data) is a response to the regular communication frame (request data) from the control device (1) 101.
Each of the control device (1) 101, the control device (3) 103, and the control device (4) 104 determines that the control device (2) 102 holds the transmission right by analyzing the token frame.
Since the control device (3) 103 and the control device (4) 104 each have an irregular communication frame addressed to the control device (2) 102, the irregularity communication frame is transmitted to the control device (2) 102.
The switching hub performs buffering of the transmitted irregular communication frame, and sequentially transmits the irregular communication frame from the control device (3) 103 and the irregular communication frame from the control device (4) 104 to the control device (2) 102. Send to.
In this case, even if the irregular communication frame is transmitted to the control device (2) 102, the irregular amount is not reduced (n = 1 remains).
When the transmission of the regular communication frame is completed, the control device (2) 102 transmits the token frame to the control device (1) 101, the control device (3) 103, and the control device (4) 104.
In the token frame transmitted by the control device (2) 102, it is notified that the control device (3) 103 holds the transmission right.

S13: When the control device (3) 103 holds the transmission right The control device (3) 103 transmits a periodic communication frame (response data) to the control device (1) 101.
Each of the control device (1) 101, the control device (2) 102, and the control device (4) 104 determines that the control device (3) 103 holds the transmission right by analyzing the token frame.
Since there is no irregular communication frame addressed to the control device (3) 103 in any of the control devices, the irregular communication frame is not transmitted.
When the transmission of the regular communication frame is completed, the control device (3) 103 transmits the token frame to the control device (1) 101, the control device (2) 102, and the control device (4) 104.
In the token frame transmitted by the control device (3) 103, it is notified that the control device (4) 104 holds the transmission right.

S14: When the control device (4) 104 holds the transmission right The control device (4) 104 transmits a periodic communication frame (response data) to the control device (1) 101.
Each of the control device (1) 101, the control device (2) 102, and the control device (3) 103 determines that the control device (4) 104 holds the transmission right by analyzing the token frame.
Since there is no irregular communication frame addressed to the control device (4) 104 in any of the control devices, the irregular communication frame is not transmitted.
When the transmission of the regular communication frame is completed, the control device (4) 104 transmits the token frame to the control device (1) 101, the control device (2) 102, and the control device (3) 103.
In the token frame transmitted by the control device (4) 104, it is notified that the control device (1) 101 holds the transmission right.

S15: Repeat The above S11 to S14 are repeated.

*** Explanation of the effect of the embodiment ***
As described above, by taking advantage of the characteristics of full-duplex communication and performing irregular communication from other control devices to the control device that holds the transmission right, the opportunity to perform irregular communication is increased compared to conventional methods. In addition, it is possible to improve the transmission efficiency of irregular communication.
Further, since the control device holding the transmission right can perform irregular communication other than when performing the regular communication, the amount of irregular communication from the control device holding the transmission right is reduced, and the transmission of the periodic communication is performed. Efficiency is also improved.
Note that the communication method according to the present embodiment has a configuration in which control devices that do not cause frame collisions between control devices are connected in a 1: 1 manner, or a switching hub in which each control device has a frame buffering function ( It is applied to a configuration in which the topology is a star type connected to a relay device.

*** Explanation of hardware configuration example ***
Finally, a hardware configuration example of the control device 100 will be described with reference to FIG.
The control device 100 is a computer.
The control device 100 includes hardware such as a processor 901, an auxiliary storage device 902, a memory 903, a communication device 904, an input interface 905, and a display interface 906.
The processor 901 is connected to other hardware via the signal line 910, and controls these other hardware.
The input interface 905 is connected to the input device 907.
The display interface 906 is connected to the display 908.

The processor 901 is an IC (Integrated Circuit) that performs processing.
The processor 901 is, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or a GPU (Graphics Processing Unit).
The auxiliary storage device 902 is, for example, a ROM (Read Only Memory), a flash memory, or an HDD (Hard Disk Drive).
The memory 903 is, for example, a RAM (Random Access Memory).
The communication frame buffer 1003 in FIG. 2 is realized by the auxiliary storage device 902 or the memory 903.
The communication device 904 includes a receiver 9041 that receives data and a transmitter 9042 that transmits data.
The communication device 904 is, for example, a communication chip or a NIC (Network Interface Card).
The physical layers of the frame receiving unit 1001 and the frame transmitting unit 1004 in FIG. 2 are realized by the communication device 904.
The input interface 905 is a port to which the cable 911 of the input device 907 is connected.
The input interface 905 is, for example, a USB (Universal Serial Bus) terminal.
The display interface 906 is a port to which the cable 912 of the display 908 is connected.
The display interface 906 is, for example, a USB terminal or an HDMI (registered trademark) (High Definition Multimedia Interface) terminal.
The input device 907 is, for example, a mouse, a keyboard, or a touch panel.
The display 908 is, for example, an LCD (Liquid Crystal Display).

In the auxiliary storage device 902, the frame receiving unit 1001, the transmission right determining unit 1002, and the frame transmitting unit 1004 (hereinafter, the frame receiving unit 1001, the transmission right determining unit 1002, and the frame transmitting unit 1004 shown in FIG. A program that realizes the function of “denoted” is stored.
This program is loaded into the memory 903, read into the processor 901, and executed by the processor 901.
Further, the auxiliary storage device 902 also stores an OS (Operating System).
Then, at least a part of the OS is loaded into the memory 903, and the processor 901 executes a program that realizes the function of “unit” while executing the OS.
Although one processor 901 is illustrated in FIG. 7, the control device 100 may include a plurality of processors 901.
A plurality of processors 901 may execute a program for realizing the function of “unit” in cooperation with each other.
In addition, information, data, signal values, and variable values indicating the processing results of “unit” are stored in the memory 903, the auxiliary storage device 902, or a register or cache memory in the processor 901.
A program for realizing the function of “part” is stored in a storage medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD.

The “part” may be provided as “circuitry”.
Further, “part” may be read as “circuit”, “process”, “procedure”, or “processing”.
“Circuit” and “Circuitry” include not only the processor 901 but also other types of processing circuits such as a logic IC or GA (Gate Array) or ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). It is a concept to include.

100 control device, 101 control device (1), 102 control device (2), 103 control device (3), 104 control device (4), 1001 frame reception unit, 1002 transmission right discrimination unit, 1003 communication frame buffer, 1004 frame Transmitter.

Claims

A communication device included in a communication system including a plurality of communication devices and performing token passing between the plurality of communication devices,
A communication frame buffer for storing communication frames addressed to other communication devices;
A transmission right determination unit for determining a communication device that currently holds the transmission right among the plurality of communication devices;
When the communication device that currently holds the transmission right is another communication device, and the communication frame addressed to the transmission right holding communication device that is another communication device that currently holds the transmission right is stored in the communication frame buffer, A communication apparatus comprising: a frame transmission unit configured to transmit a communication frame addressed to the transmission right holding communication apparatus stored in the communication frame buffer to the transmission right holding communication apparatus.
The communication device further includes:
A frame receiving unit for receiving a token frame to which a communication device holding a transmission right is notified;
The transmission right determination unit
The communication apparatus according to claim 1, wherein each time the token frame is received by the frame reception unit, the token frame is analyzed to determine a communication apparatus that holds a current transmission right among the plurality of communication apparatuses.
The frame transmission unit includes:
The communication apparatus according to claim 1, wherein a communication frame addressed to the transmission right holding communication apparatus is transmitted to the transmission right holding communication apparatus in parallel with transmission of a communication frame based on the transmission right in the transmission right holding communication apparatus.
The transmission right determination unit
Notifying the communication frame buffer of the transmission right holding communication device,
The communication frame buffer is
When a communication frame addressed to the transmission right holding communication device notified from the transmission right determination unit is stored, a communication frame addressed to the transmission right holding communication device is output to the frame transmission unit,
The frame transmission unit includes:
The communication device according to claim 1, wherein the communication frame addressed to the transmission right holding communication device output from the communication frame buffer is transmitted to the transmission right holding communication device.
A communication device that includes a plurality of communication devices and is included in a communication system in which token passing is performed between the plurality of communication devices, and includes a communication frame buffer that stores communication frames addressed to other communication devices. The device
Determining a communication device that currently holds a transmission right among the plurality of communication devices;
When the communication device that currently holds the transmission right is another communication device, and the communication frame addressed to the transmission right holding communication device that is another communication device that currently holds the transmission right is stored in the communication frame buffer, A communication method of transmitting a communication frame addressed to the transmission right holding communication device stored in the communication frame buffer to the transmission right holding communication device.
A communication device that includes a plurality of communication devices and is included in a communication system in which token passing is performed between the plurality of communication devices, and includes a communication frame buffer that stores communication frames addressed to other communication devices. To the device,
A transmission right determination process for determining a communication apparatus that currently holds the transmission right among the plurality of communication apparatuses;
When the communication device that currently holds the transmission right is another communication device, and the communication frame addressed to the transmission right holding communication device that is another communication device that currently holds the transmission right is stored in the communication frame buffer, A communication program for executing a frame transmission process for transmitting a communication frame addressed to the transmission right holding communication device stored in the communication frame buffer to the transmission right holding communication device.