WO2013111285A1

WO2013111285A1 - Communication apparatus, communication method, and program

Info

Publication number: WO2013111285A1
Application number: PCT/JP2012/051540
Authority: WO
Inventors: 大介長川
Original assignee: 三菱電機株式会社
Priority date: 2012-01-25
Filing date: 2012-01-25
Publication date: 2013-08-01

Abstract

If new data to be transmitted occurs while a data transmitting unit (105) is transmitting data, a data arbitrating unit (106) determines whether priority is given to the data being transmitted by the data transmitting unit (105) or to the new data. If the priority is given to the new data, the data arbitration unit (106) outputs, to the data transmitting unit, a data change instruction that instructs a data change. When having received the data change instruction from the data arbitration unit (106) during the data transmission, the data transmitting unit (105) suspends the transmission of the data being transmitted and starts the transmission of the new data.

Description

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

The present invention relates to a data transmission technique.

For example, in a network including a master device and a slave device, when the slave device detects the occurrence of a failure in the network, the slave device notifies the master device of the occurrence of the failure.
In the conventional failure notification method, the slave device notifies the master device of the failure by broadcasting a failure notification frame to the entire network (for example, Patent Document 1).

JP 2003-289325 A

In the conventional failure notification method, if other communication is performed at the start of transmission of the failure notification frame, the transmission of the failure notification frame is waited until the other communication is completed. Notification is delayed.
In other words, when important data such as a failure notification frame is newly generated during transmission of certain data, until the transmission of the data being transmitted is completed in the conventional method, even if it is important data Since transmission is awaited, there is a problem that transmission of important data is delayed.

This invention is mainly intended to solve the above-described problems, and it is a main object to realize a configuration in which new data can be preferentially transmitted even during data transmission.

The communication device according to the present invention is
A data transmission unit for transmitting data;
When new data to be transmitted occurs while the data transmission unit is transmitting data, the data transmission unit determines which of the data being transmitted and the new data has priority, A data arbitration unit that outputs a data switching instruction to instruct data switching to the data transmission unit when giving priority to the new data;
The data transmitter is
When a data switching instruction is input from the data arbitration unit during data transmission, transmission of the data being transmitted is interrupted and transmission of the new data is started.

In the present invention, when the data arbitration unit determines which of the data being transmitted and the new data is prioritized by the data transmitting unit, and when giving priority to the new data, the data transmitting unit Is interrupted and transmission of new data is started.
For this reason, important data can be transmitted first, and a situation in which transmission of important data is delayed can be avoided.

1 is a diagram illustrating a configuration example of a communication system according to Embodiment 1. FIG. FIG. 3 illustrates a configuration example of a slave device according to the first embodiment. FIG. 3 shows an example of a communication frame according to the first embodiment. FIG. 3 is a flowchart showing an operation example of the slave device according to the first embodiment. FIG. 3 is a flowchart showing an operation example of the slave device according to the first embodiment. FIG. 3 is a flowchart showing an operation example of the slave device according to the first embodiment. FIG. 3 is a diagram illustrating a hardware configuration example of a slave device according to the first embodiment.

Embodiment 1 FIG.
In the present embodiment, description will be given by taking a tree topology network in which token passing is performed as an example.

FIG. 1 illustrates an example of a tree topology network according to the first embodiment.
In the present embodiment, one master device 200 and a plurality of slave devices 100 are connected via a switch 300.
The master device 200 and the slave device 100 are collectively referred to as a station or a node.
When receiving the frame, the slave device 100, the master device 200, and the switch 300 relay the received frame to all ports that are not reception ports. Thereby, it is possible to communicate even between nodes that are not adjacent to each other.
Note that the slave device 100 corresponds to an example of a communication device.

In the master device 200 and the plurality of slave devices 100, the order in which the tokens are circulated is determined in advance, and the tokens circulate between the master device 200 and the plurality of slave devices 100 according to the circulation order.
The node acquires the transmission right by acquiring the token.
The master device 200 that has acquired the token makes a request for information collection, data distribution, and the like to the slave device 100 as a master of the tree topology of FIG.
The slave device 100 that has acquired the token responds to the master device 200 with the requested data in response to the information collection request from the master device 200.
Further, the slave device 100 performs an operation based on the data distributed from the master device 200.
When a failure occurs in the network, each slave device 100 notifies the master device 200 of the failure regardless of the presence or absence of a token.

FIG. 2 shows a configuration example of the slave device 100 according to the present embodiment.
Note that the plurality of slave devices 100 shown in FIG. 1 each have the configuration shown in FIG.

In FIG. 2, the failure detection unit 101 includes, for example, the own station, the master device 200 and the slave device 100 adjacent to the own station, and the communication line between the master device 200 and the slave device 100 adjacent to the own station and the own station. A failure notification frame for notifying the occurrence of a failure is generated when a failure detection target is detected and a failure has occurred in the failure detection target.
The normal frame generation unit 102 generates a normal frame related to normal operation other than the failure notification frame transmitted from the own station.
The normal frame is a frame for making a response to an information collection request from the master device 200, for example.
The failure detection unit 101 and the normal frame generation unit 102 correspond to an example of a data generation unit.

The transmission arbitration unit 103 includes a data reception unit 104, a data transmission unit 105, and a data arbitration unit 106.

The data receiving unit 104 inputs a reception frame from an adjacent other station (which may be either the master device 200 or the slave device 100).
The data receiving unit 104 may receive a normal frame or a failure notification frame.

The data transmission unit 105 transmits a frame to another station (which may be either the master device 200 or the slave device 100) adjacent to the side opposite to the input side.
The data transmission unit 105 may transmit a normal frame or a failure notification frame.
Further, when transmitting a normal frame, the data transmission unit 105 stores the normal frame to be transmitted in a retransmission frame buffer 107 described later in parallel with the transmission.

The data arbitration unit 106 receives the reception frame (normal frame, failure notification frame) received by the data reception unit 104, receives the failure notification frame generated by the failure detection unit 101, and the normal frame generated by the normal frame generation unit 102 The frame is input, and the input normal frame and failure notification frame are output to the data transmission unit 105.
Then, when a new failure notification frame occurs while the data transmission unit 105 is transmitting a normal frame (when a new failure notification frame is input from the data reception unit 104, the data arbitration unit 106 The data transmission unit 105 is instructed to transmit the failure notification frame to another station in preference to the normal frame in both cases when a failure notification frame is newly input from 101.
More specifically, the data arbitration unit 106 outputs, to the data transmission unit 105, a data switching instruction that instructs to switch from a normal frame to a failure notification frame for transmission.

The retransmission frame buffer 107 buffers the normal frame transmitted by the data transmission unit 105.
The retransmission frame buffer 107 corresponds to an example of a buffer unit.

FIG. 3 shows an example of the data structure of a communication frame 500 used as a normal frame or a failure notification frame communicated in the tree topology according to the present embodiment.

As shown in FIG. 3, a header 501 is provided in the communication frame 500.
The header 501 is a data area in the communication frame 500 for identifying a failure notification frame and a normal frame.
The data transmission unit 105 and the data arbitration unit 106 can identify the failure notification frame and the normal frame by confirming the contents of the header 501.
Hereinafter, the communication frame 500 is also simply referred to as a frame.

Next, an operation example of the slave device 100 according to the present embodiment will be described.
First, an outline of the operation of the slave device 100 according to the present embodiment will be described, and then details of the operation of the slave device 100 according to the present embodiment will be described with reference to a flowchart.
In the following, description of token transmission / reception is omitted for the sake of simplicity.

Here, it is assumed that the failure detection unit 101 detects that a failure has occurred in the failure detection object.
The detected failure includes, for example, a failure in the own station (such as a data error in the memory), a network failure between the adjacent master device 200 and the slave device 100 (cable disconnection, unreachable frame to be reached) Etc.).

The failure detection unit 101 generates a failure notification frame and outputs it to the transmission arbitration unit 103.
In addition, the normal frame generation unit 102 generates a normal frame to be transmitted from the own station and outputs the normal frame to the transmission arbitration unit 103.
In the transmission arbitration unit 103, the data arbitration unit 106 receives the failure notification frame from the failure detection unit 101 and the normal frame from the normal frame generation unit 102.

The data reception unit 104 in the transmission arbitration unit 103 receives a frame (a failure notification frame and a normal frame are mixed) from another station, and outputs the received frame to the data arbitration unit 106.
The data arbitration unit 106 and the data transmission unit 105 can classify the input frame into a failure notification frame and a normal frame based on the difference in the header 501.
Then, the data arbitration unit 106 and the data transmission unit 105 transmit the failure notification frame with priority.
Further, when transmitting a normal frame, the data transmission unit 105 stores the normal frame to be transmitted in the retransmission frame buffer 107 in parallel with the transmission.
Here, if the data arbitration unit 106 receives a failure notification frame from the failure detection unit 101 or the data reception unit 104 while the data transmission unit 105 is transmitting a normal frame to another station, the data arbitration unit 106 The unit 105 causes the transmission of the normal frame to be interrupted and starts the transmission of the failure notification frame.
Then, when the transmission of the failure notification frame is completed, the data transmission unit 105 reads the normal frame whose transmission is interrupted from the retransmission frame buffer 107, and resumes the transmission of the normal frame.

4, 5, and 6 are flowcharts illustrating an operation example of the slave device 100 according to the present embodiment.
The operation of slave device 100 according to the present embodiment will be described below according to the flowchart.

First, in S101, the data arbitration unit 106 confirms whether or not the data transmission unit 105 is transmitting a frame.
For example, a flag indicating whether or not the data transmission unit 105 is transmitting a frame (hereinafter referred to as a transmission flag) is provided in a predetermined memory in the slave device 100, and the data transmission unit 105 transmits a frame. The transmission flag is set to ON when it starts, and the transmission flag is set to OFF when frame transmission is completed.
Then, the data arbitration unit 106 refers to the transmission flag and determines whether the data transmission unit 105 is transmitting a frame.

If YES in S101, in S102, the data arbitration unit 106 checks whether the frame being transmitted by the data transmission unit 105 is a received frame (a failure notification frame from another station or a normal frame from another station). .
For example, in addition to the above-described frame transmission flag, a flag (hereinafter referred to as a reception frame flag) indicating whether or not the frame being transmitted by the data transmission unit 105 is a reception frame is provided. If the middle frame is a received frame, the received frame flag is turned on. If the frame being transmitted is not a received frame, the received frame flag is turned off.
Then, the data arbitration unit 106 refers to the reception frame flag to determine whether or not the frame being transmitted by the data transmission unit 105 is a reception frame.
The data transmission unit 105 can determine whether the transmission source of the frame is another station or the own station by referring to the transmission source address in the header 501 of the frame.

If YES in S102, in S103, the failure detection unit 101 confirms whether or not to generate a failure notification frame.

In the case of YES in S <b> 103, in S <b> 104, the failure detection unit 101 generates a failure notification frame and outputs it to the transmission arbitration unit 103.
In the transmission arbitration unit 103, the data arbitration unit 106 inputs a failure notification frame.

Next, in S105, the data arbitration unit 106 confirms whether the frame being transmitted is a received frame and is a normal frame.
For example, in addition to the above-described frame transmission flag and reception frame flag, a flag (hereinafter referred to as a frame type flag) indicating whether the frame being transmitted by the data transmission unit 105 is a normal frame is provided, and the data transmission unit 105, the frame type flag is turned on when the frame being transmitted is a normal frame, and the frame type flag is turned off when the frame being transmitted is a failure notification frame.
Then, the data arbitration unit 106 refers to the frame type flag to determine whether or not the received frame being transmitted by the data transmission unit 105 is a normal frame.
As described above, the data transmission unit 105 can determine whether the frame is a normal frame or a failure notification frame by referring to the frame header 501.

If YES in S105, in S106, the data arbitration unit 106 determines to prioritize transmission of the failure notification frame, and the data arbitration unit 106 outputs a data switching instruction and a failure notification frame to the data transmission unit 105. .
That is, the data arbitration unit 106 interrupts transmission of a normal frame that is a received frame, and transmits the failure notification frame generated by the failure detection unit 101 of the local station to the master device 200 via another station. To instruct.
Then, the data transmission unit 105 interrupts transmission of the normal frame being transmitted, and starts transmitting the failure notification frame generated by the failure detection unit 101 of the local station (S106).
The data transmission unit 105 interrupts transmission of the normal frame being transmitted, but continues to store the normal frame in the retransmission frame buffer 107, and stores the normal frame in the retransmission frame buffer 107 and the failure notification frame. Send in parallel.
Thereafter, after the transmission of the failure notification frame is completed, the data transmission unit 105 reads the normal frame whose transmission is interrupted from the retransmission frame buffer 107 and transmits the read normal frame to another adjacent station (S106).

4, 5, and 6, the failure notification frame generated by the failure detection unit 101 of the local station is referred to as a failure notification frame (transmission), and the normal frame generated by the normal frame generation unit 102 of the local station is represented. The normal frame (transmission) is denoted, the failure notification frame received from another station is denoted as a failure notification frame (reception), and the normal frame received from another station is denoted as a normal frame (reception).

If NO in S105, the received frame being transmitted by the data transmission unit 105 is a failure notification frame. Therefore, in S107, the data arbitration unit 106 sends the failure detection frame input from the failure detection unit 101 to the data transmission unit 105. The data transmission unit 105 outputs the failure notification frame received from the other station, and then transmits the failure notification frame generated by the failure detection unit 101 of the local station to the master device 200 via the adjacent other station.

If NO in S103, the normal frame generation unit 102 confirms whether or not to generate a normal frame in S108. If YES, the normal frame generation unit 102 transmits the generated normal frame in S109. Output to the arbitration unit 103.

The data arbitration unit 106 inputs the normal frame from the normal frame generation unit 102 and outputs the input normal frame to the data transmission unit 105.
The data transmission unit 105 transmits the normal frame generated by the normal frame generation unit 102 of the local station after completing the transmission of the received frame (failure notification frame from the other station or normal frame from the other station) (S110). .

In the case of NO in S102, in S111, the transmission arbitration unit 103 confirms whether or not a received frame has been detected.
That is, the data arbitration unit 106 confirms whether or not a reception frame is input from the data reception unit 104.

In the case of YES in S111, in S112, the data arbitration unit 106 checks whether or not the frame being transmitted by the data transmission unit 105 is a normal frame.
For example, the data arbitration unit 106 refers to the above-described frame type flag to determine whether or not the frame being transmitted by the data transmission unit 105 is a normal frame.

In the case of YES in S112, in S113, the data arbitration unit 106 checks whether the received frame input from the data receiving unit 104 is a failure notification frame.
Specifically, the data arbitration unit 106 confirms the header 501 of the received frame and confirms whether or not the received frame is a failure notification frame.

If YES in S113, the data arbitration unit 106 determines to give priority to the transmission of the failure notification frame. In S114, the data arbitration unit 106 instructs the data transmission unit 105 to perform a data switching instruction and a failure notification from another station. Frame and output.
That is, the data arbitration unit 106 interrupts transmission of the normal frame generated by the normal frame generation unit 102 of the local station, and transmits the failure notification frame from the other station to the master device 200 via the other station. To instruct.
Then, the data transmission unit 105 interrupts transmission of the normal frame being transmitted and starts transmission of a failure notification frame from another station (S114).
The data transmission unit 105 interrupts transmission of the normal frame being transmitted, but continues to store the normal frame in the retransmission frame buffer 107, and stores the normal frame in the retransmission frame buffer 107 and the failure notification frame. Send in parallel.
Thereafter, after the transmission of the failure notification frame is completed, the data transmission unit 105 reads the normal frame whose transmission is interrupted from the retransmission frame buffer 107 and transmits the read normal frame to another adjacent station (S106).

In the case of NO in S113, in S115, the data arbitration unit 106 outputs the normal frame from the other station to the data transmission unit 105, and the data transmission unit 105 generates the normal frame generated by the normal frame generation unit 102 of its own station. After the frame is transmitted, a received frame (a normal frame from another station) is transmitted.
At this time, the data transmission unit 105 stores the normal frame to be transmitted in the retransmission frame buffer 107 in parallel with the transmission.

In the case of NO in S112, in S116, the data arbitration unit 106 checks whether the received frame input from the data receiving unit 104 is a failure notification frame.
Specifically, the data arbitration unit 106 confirms the header 501 of the received frame and confirms whether or not the received frame is a failure notification frame.

If YES in S116, in S117, the data arbitration unit 106 outputs the failure notification frame from the other station to the data transmission unit 105, and the data transmission unit 105 transmits the failure notification frame of the local station to the other station. A failure notification frame from is transmitted.

In the case of NO in S116, in S118, the data arbitration unit 106 outputs the normal frame from the other station to the data transmission unit 105, and the data transmission unit 105 receives the failure notification frame of the local station from the other station. The normal frame is transmitted.
At this time, the data transmission unit 105 stores the normal frame to be transmitted in the retransmission frame buffer 107 in parallel with the transmission.

In the case of NO in S101, in S119, the transmission arbitration unit 103 confirms whether or not a received frame has been detected.
That is, the data arbitration unit 106 confirms whether or not a reception frame is input from the data reception unit 104.

In the case where S119 is YES, in S120, the data arbitration unit 106 confirms whether or not the received frame input from the data receiving unit 104 is a failure notification frame.
Specifically, the data arbitration unit 106 confirms the header 501 of the received frame and confirms whether or not the received frame is a failure notification frame.

In the case of YES in S120, in S121, the data arbitration unit 106 outputs the failure notification frame from the other station to the data transmission unit 105, and the data transmission unit 105 receives the failure notification frame from the other station as an adjacent station. To the master device 200.

In the case of NO in S120, in S122, the data arbitration unit 106 outputs the normal frame from the other station to the data transmission unit 105, and the data transmission unit 105 sends the normal frame from the other station to the adjacent other station. Send.
Further, the data transmission unit 105 stores normal frames from other stations in the retransmission frame buffer 107 in parallel with the transmission.

If NO in S119, in S123, the failure detection unit 101 confirms whether or not to generate a failure notification frame.

If YES in S123, the failure detection unit 101 generates a failure notification frame and outputs it to the transmission arbitration unit 103 in S124.

The data arbitration unit 106 receives the failure detection frame from the failure detection unit 101 and outputs the input failure detection frame to the data transmission unit 105.
In S125, the data transmission unit 105 transmits the failure notification frame generated by the failure detection unit 101 of the local station to the master device 200 via the adjacent station.

If NO in S123, the normal frame generation unit 102 confirms whether or not to generate a normal frame in S126. If YES, the normal frame generation unit 102 transmits the generated normal frame in S127. Output to the arbitration unit 103.

The data arbitration unit 106 inputs the normal frame from the normal frame generation unit 102 and outputs the input normal frame to the data transmission unit 105.
In S128, the data transmission unit 105 transmits the normal frame generated by the normal frame generation unit 102 of the local station to another station.
At this time, the data transmission unit 105 stores the normal frame to be transmitted in the retransmission frame buffer 107 in parallel with the transmission.

As described above, in the present embodiment, even when a normal frame is being transmitted, the failure notification frame is transmitted by overtaking the normal frame. Therefore, the failure notification is not delayed due to the transmission of the normal frame.
As a result, the master device that has received the failure notification can quickly stop the operation of each station, thereby preventing the influence (malfunction of the device, physical harm to the human body, etc.) due to the malfunction of the device.

In the above, an example has been described in which when a failure notification frame is newly generated during transmission of a normal frame, transmission of the normal frame is interrupted and transmission of the failure notification frame is started.
However, the data handled by the data transmission unit 105 and the data arbitration unit 106 is not limited to the combination of the normal frame and the failure notification frame, and may be any data.
That is, when new data to be transmitted occurs while the data transmission unit 105 is transmitting any data, the data arbitration unit 106 determines whether the data transmission unit 105 transmits the data being transmitted to the new data. When it is determined which is prioritized and new data is prioritized, a data switching instruction for instructing data switching is output to the data transmission unit 105.
When the data transmission unit 105 receives a data switching instruction from the data arbitration unit 106 during data transmission, the data transmission unit 105 interrupts transmission of the data being transmitted and starts transmission of new data.

In the above description, the description is given for a network in which token passing is performed. However, a CSMA / CD (Carrier Sense Multiple Access Collision Detection) type network may be targeted.

As described above, in the present embodiment, the communication device including the following means has been described.
(A) means for identifying the type of frame;
(B) means for buffering the frame being transmitted;
(C) Means for interrupting frame transmission and starting transmission of another frame.

Finally, a hardware configuration example of the slave device 100 according to the present embodiment will be described.
FIG. 7 is a diagram illustrating an example of hardware resources of the slave device 100 illustrated in the present embodiment.
The configuration in FIG. 7 is merely an example of the hardware configuration of the slave device 100, and the hardware configuration of the slave device 100 is not limited to the configuration illustrated in FIG. .

In FIG. 7, the slave device 100 includes a CPU 911 (also referred to as a central processing unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, and a processor) that executes a program.
The CPU 911 is connected to, for example, a ROM (Read Only Memory) 913, a RAM (Random Access Memory) 914, a communication board 915, a display device 901, a keyboard 902, a mouse 903, and a magnetic disk device 920 via a bus 912. Control hardware devices.
Further, the CPU 911 may be connected to an FDD 904 (Flexible Disk Drive), a compact disk device 905 (CDD), a printer device 906, and a scanner device 907. Further, instead of the magnetic disk device 920, a storage device such as an SSD (Solid State Drive), an optical disk device, or a memory card (registered trademark) read / write device may be used.
The RAM 914 is an example of a volatile memory. The storage media of the ROM 913, the FDD 904, the CDD 905, and the magnetic disk device 920 are an example of a nonvolatile memory. These are examples of the storage device.
The “retransmission frame buffer 107” described in the present embodiment is realized by the RAM 914, the magnetic disk device 920, and the like.
A communication board 915, a keyboard 902, a mouse 903, a scanner device 907, and the like are examples of input devices.
The communication board 915, the display device 901, the printer device 906, and the like are examples of output devices.

As shown in FIG. 1, the communication board 915 is connected to a network.
For example, the communication board 915 is connected to a LAN (local area network), the Internet, a WAN (wide area network), a SAN (storage area network), and the like.

The magnetic disk device 920 stores an operating system 921 (OS), a window system 922, a program group 923, and a file group 924.
The programs in the program group 923 are executed by the CPU 911 using the operating system 921 and the window system 922.

The RAM 914 temporarily stores at least part of the operating system 921 program and application programs to be executed by the CPU 911.
The RAM 914 stores various data necessary for processing by the CPU 911.

The ROM 913 stores a BIOS (Basic Input Output System) program, and the magnetic disk device 920 stores a boot program.
When the slave device 100 is activated, the BIOS program in the ROM 913 and the boot program in the magnetic disk device 920 are executed, and the operating system 921 is activated by the BIOS program and the boot program.

The program group 923 stores programs that execute the functions described as “˜units” in the description of the present embodiment.
The program is read and executed by the CPU 911.

In the description of the present embodiment, the file group 924 includes “determination of”, “detection of”, “determination of”, “evaluation of”, “determination of”, “selection of”, Information, data, signal values, variable values, encryption keys / decryption keys, random values and parameters indicating the results of the processing described as “input of”, “output of”, etc. It is stored as each item of “Database”.
The “˜file” and “˜database” are stored in a storage medium such as a disk or memory.
Information, data, signal values, variable values, and parameters stored in a storage medium such as a disk or memory are read out to the main memory or cache memory by the CPU 911 via a read / write circuit.
The read information, data, signal value, variable value, and parameter are used for CPU operations such as extraction, search, reference, comparison, calculation, calculation, processing, editing, output, printing, and display.
Information, data, signal values, variable values, and parameters are stored in the main memory, registers, cache memory, and buffers during the CPU operations of extraction, search, reference, comparison, calculation, processing, editing, output, printing, and display. It is temporarily stored in a memory or the like.
In addition, the arrows in the flowchart described in this embodiment mainly indicate input / output of data and signals.
Data and signal values are recorded in a storage medium such as a memory of the RAM 914, a flexible disk of the FDD 904, a compact disk of the CDD 905, a magnetic disk of the magnetic disk device 920, other optical disks, mini disks, and DVDs.
Data and signals are transmitted online via a bus 912, signal lines, cables, or other transmission media.

In the description of the present embodiment, what is described as “to part” and “to means” may be “to circuit”, “to device”, and “to device”. It may be “step”, “˜procedure”, “˜processing”.
That is, the “communication method” according to the present invention can be realized by the steps, procedures, and processes shown in the flowchart described in the present embodiment.
Further, what is described as “˜unit” and “˜means” may be realized by firmware stored in the ROM 913.
Alternatively, it may be implemented only by software, or only by hardware such as elements, devices, substrates, and wirings, by a combination of software and hardware, or by a combination of firmware.
Firmware and software are stored as programs in a storage medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, and a DVD.
The program is read by the CPU 911 and executed by the CPU 911.
In other words, the program causes the computer to function as “to part” and “to means” in the present embodiment. Alternatively, the procedures and methods of “˜unit” and “˜means” of the present embodiment are executed by a computer.

As described above, the slave device 100 described in this embodiment includes a CPU that is a processing device, a memory that is a storage device, a magnetic disk, a keyboard that is an input device, a mouse, a communication board, and a display device that is an output device, a communication board, and the like. Computer.
As described above, the functions indicated as “˜unit” and “˜means” are realized by using these processing devices, storage devices, input devices, and output devices.

100 slave device, 101 failure detection unit, 102 normal frame generation unit, 103 transmission arbitration unit, 104 data reception unit, 105 data transmission unit, 106 data arbitration unit, 107 retransmission frame buffer, 200 master device, 300 switch.

Claims

A data transmission unit for transmitting data;
When new data to be transmitted occurs while the data transmission unit is transmitting data, the data transmission unit determines which of the data being transmitted and the new data has priority, A data arbitration unit that outputs a data switching instruction to instruct data switching to the data transmission unit when giving priority to the new data;
The data transmitter is
When a data switching instruction is input from the data arbitration unit during data transmission, the communication apparatus stops transmission of data being transmitted and starts transmission of the new data.
The communication device further includes:
A buffer unit for storing data;
The data transmitter is
Sending data in parallel with storing data in the buffer unit,
When a data switching instruction is input from the data arbitration unit during data transmission, the transmission of the data being transmitted is interrupted while the data being transmitted is being stored in the buffer unit, and the new data is transmitted. The communication device according to claim 1, wherein the communication device is started.
The data transmitter is
3. The communication apparatus according to claim 2, wherein after the transmission of the new data is completed, the transmission of the data whose transmission is interrupted is started using the data stored in the buffer unit.
The communication device
A data generation unit for generating data;
The data arbitration unit
When the data generation unit generates new data to be transmitted while the data transmission unit is transmitting the data generated by the data generation unit, the data transmission unit and the data being transmitted The communication apparatus according to claim 1, wherein priority is given to which of the new data generated by the generation unit.
The communication device further includes:
A data receiving unit for receiving data;
The data arbitration unit
When the data generation unit generates new data to be transmitted while the data transmission unit is transmitting data received by the data reception unit, the data transmission unit and the data being transmitted The communication apparatus according to claim 4, wherein which of the new data generated by the generation unit is prioritized.
The data arbitration unit
When the data receiving unit receives new data to be transmitted while the data transmitting unit is transmitting the data generated by the data generating unit, the data transmitting unit and the data being transmitted 6. The communication apparatus according to claim 5, wherein the receiving unit determines which of the new data received is prioritized.
The communication device further includes:
A data receiving unit for receiving data;
The data arbitration unit
When the data transmission unit receives new data to be transmitted while the data transmission unit is transmitting data received by the data reception unit, the data transmission unit transmits the data being transmitted and the data The communication apparatus according to claim 4, wherein the receiving unit determines which of the new data received is prioritized.
The data arbitration unit
When the new data is failure notification data for notifying the occurrence of a failure in the failure detection target, and the data being transmitted by the data transmission unit is data other than the failure notification data, the new data The communication apparatus according to claim 1, wherein priority is given to the communication apparatus.
If new data to be sent occurs while sending data,
Deciding which of the data being transmitted and the new data should be prioritized, and when prioritizing the new data, interrupting the transmission of the data being transmitted and starting the transmission of the new data A communication method characterized by the above.
If new data to be sent occurs while sending data,
A process of deciding which of the data being transmitted and the new data should be prioritized, and when prioritizing the new data, interrupting the transmission of the data being transmitted and starting the transmission of the new data A program that causes a computer to execute.