WO2017126077A1 - 通信システム、通信装置及び通信方法 - Google Patents
通信システム、通信装置及び通信方法 Download PDFInfo
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- WO2017126077A1 WO2017126077A1 PCT/JP2016/051691 JP2016051691W WO2017126077A1 WO 2017126077 A1 WO2017126077 A1 WO 2017126077A1 JP 2016051691 W JP2016051691 W JP 2016051691W WO 2017126077 A1 WO2017126077 A1 WO 2017126077A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/02—Speed or phase control by the received code signals, the signals containing no special synchronisation information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/0016—Arrangements for synchronising receiver with transmitter correction of synchronization errors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0658—Clock or time synchronisation among packet nodes
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/40—Bus structure
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/403—Bus networks with centralised control, e.g. polling
- H04L12/4035—Bus networks with centralised control, e.g. polling in which slots of a TDMA packet structure are assigned based on a contention resolution carried out at a master unit
Definitions
- the present invention relates to a communication system, a communication apparatus, and a communication method that perform timing synchronization.
- timing synchronization In a system in which a plurality of devices connected to the network operate in cooperation, it is necessary to match the control timing of each device by matching the time measured by each device. Matching the control timings of a plurality of devices is called timing synchronization.
- the timing at which one device transports the material matches the timing at which the other device cuts the material, the material is being transported. Also, the desired part of the material is cut.
- a synchronization master device that is a timing synchronization master and a synchronization slave device that is a timing synchronization slave communicate with each other at a predetermined communication time interval. Accordingly, the synchronization slave device performs timing synchronization with the synchronization master device.
- the transmission time interval of the transmission data of the synchronization master device may fluctuate and the timing synchronization accuracy may decrease.
- the cause of the fluctuation of the transmission time interval is exemplified by a failure of the synchronization master device or a disturbance from a device other than the synchronization master device.
- Patent Document 1 describes a reference time transmitted from a corresponding time master device among a plurality of time master devices that transmit a reference time indicating a reference time, and a propagation delay from the time master device.
- a plurality of estimated time calculation units for calculating the estimated time of the corresponding time master device based on the time, and a current time indicating the current time based on the plurality of estimated times calculated by the plurality of estimated time calculation units.
- a time synchronization device comprising: a current time calculation unit for calculating, wherein the estimated time calculation unit discards a reference time at which a reception interval of a reference time transmitted from a corresponding time master device is equal to or greater than a threshold value (Claim 5).
- the time synchronizer described in Patent Document 1 compares the reference time reception interval with a threshold value, and discards the reference time having a long reception interval, which is considered to have caused a collision between frames. Has improved.
- the present invention has been made in view of the above, and an object of the present invention is to obtain a communication system capable of improving the accuracy of timing synchronization.
- the present invention includes a first communication device that transmits a plurality of frames at a transmission time interval shorter than the time required for transmitting the minimum frame.
- the present invention also includes a second communication device that performs timing synchronization with the first communication device based on the plurality of frames when the reception time intervals of the received frames match the transmission time interval.
- the second communication device can detect that the reception time interval of the received frames is shorter than the transmission time interval.
- the communication system according to the present invention has the effect of improving the accuracy of timing synchronization.
- FIG. 3 is a flowchart showing processing of the synchronization master communication device of the communication system according to the first exemplary embodiment.
- FIG. 1 is a flowchart showing processing of a synchronous slave communication device of a communication system according to a first exemplary embodiment.
- FIG. 1 is a diagram illustrating a hardware configuration of a hub of a communication system according to a first embodiment.
- FIG. 1 is a diagram illustrating a configuration of a communication system according to the first embodiment.
- the communication system 1 includes a synchronization master communication device 2 that transmits a plurality of frames, a hub 3 that is connected to the synchronization master communication device 2 via a cable C1 and transfers a plurality of frames received from the synchronization master communication device 2, A synchronization slave connected to the hub 3 via the cable C2 and receiving a plurality of frames transmitted from the synchronization master communication device 2 from the hub 3 and performing timing synchronization with the synchronization master communication device 2 based on the plurality of frames Communication device 4.
- the synchronization master communication device 2 corresponds to the first communication device of the present invention.
- the synchronous slave communication device 4 corresponds to the second communication device of the present invention.
- the synchronization master communication device 2 transmits a frame in which the MAC address of the synchronization slave communication device 4 is stored in the destination MAC (Media Access Control) address field of the frame to the hub 3.
- MAC Media Access Control
- the hub 3 refers to the MAC address stored in the destination MAC address field of the frame received from the synchronization master communication device 2, determines that the frame destination is the synchronization slave communication device 4, and the synchronization master communication device The frame received from 2 is transferred to the synchronous slave communication device 4.
- the communication system 1 includes a communication device 5 connected to the hub 3 via the cable C3 and a communication device 6 connected to the hub 3 via the cable C4.
- the communication device 5 transmits to the hub 3 a frame in which the MAC address of the communication device 6 is stored in the destination MAC address field of the frame.
- the hub 3 refers to the MAC address stored in the destination MAC address field of the frame received from the communication device 5, determines that the destination of the frame is the communication device 6, and communicates the frame received from the communication device 5. Transfer to device 6.
- FIG. 2 is a functional block diagram of the synchronization master communication device of the communication system according to the first embodiment.
- the synchronization master communication device 2 includes a frame generation unit 21 that generates a plurality of frames, a transmission time interval measurement unit 22 that measures transmission time intervals between the plurality of frames, and a transmission time that is shorter than the time required to transmit the minimum frame. And a transmission unit 23 that transmits a plurality of frames to the synchronous slave communication device 4 at intervals.
- the minimum frame and the time required to transmit the minimum frame will be described later.
- the transmission time interval is a time interval between the transmission completion timing of one frame and the transmission start timing of the next frame.
- FIG. 3 is a diagram illustrating a hardware configuration of the synchronization master communication device of the communication system according to the first embodiment.
- the synchronization master communication device 2 includes a transmission unit 23, a CPU (Central Processing Unit) 24, and a storage unit 25.
- the transmission unit 23, the CPU 24, and the storage unit 25 are connected via a bus B1.
- the storage unit 25 stores a frame generation program 26 and a transmission time interval measurement program 27.
- the storage unit 25 is exemplified by a flash memory (registered trademark).
- the frame generation program 26 is a program for generating a plurality of frames.
- the frame generation unit 21 that generates a plurality of frames is realized.
- the frame generation unit 21 generates a plurality of frames such that the transmission time interval between the plurality of frames is shorter than the time required for transmitting the minimum frame.
- the transmission time interval measurement program 27 is a program for measuring transmission time intervals between a plurality of frames.
- the transmission time interval measurement unit 22 that measures the transmission time intervals between a plurality of frames is realized.
- the transmission unit 23 is a physical layer circuit that bears the physical layer that is the first layer of the OSI reference model (Open Systems Interconnection reference model, ISO (International Organization for Standardization) / IEC (International Electrotechnical Commission) 7498).
- OSI reference model Open Systems Interconnection reference model, ISO (International Organization for Standardization) / IEC (International Electrotechnical Commission) 7498.
- Ethernet registered trademark, IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 802.3).
- the transmission unit 23 is connected to the hub 3 via the cable C1.
- the transmitting unit 23 transmits a plurality of frames to the synchronous slave communication device 4 at a transmission time interval shorter than the time required for transmitting the minimum frame.
- the communication physical layer has the following characteristics.
- the physical layer of communication can be branched.
- a third device can be connected to the physical layer of communication.
- the other one is awaited. For example, when communication between the first device and the second device is in progress, the communication between the third device and the fourth device is awaited.
- the minimum frame is a frame having a minimum frame length.
- the minimum frame In Ethernet (registered trademark), the minimum frame is 64 bytes long. Therefore, in Ethernet (registered trademark), the time required to transmit the minimum frame can be defined by a value obtained by dividing 64 bytes by the communication bit rate.
- the communication bit rate is exemplified by 100 Mbps (bit per second) or 1000 Mbps.
- Ethernet (registered trademark) is an example of a physical layer of communication, and the minimum frame is not limited to 64 bytes.
- the communication delay is constant under the condition where there is no frame collision. For example, if communication does not occur between the third device and the fourth device during communication between the first device and the second device, no frame collision occurs. When no frame collision occurs, the communication delay between the first device and the second device is constant.
- FIG. 4 is a functional block diagram of the synchronous slave communication device of the communication system according to the first embodiment.
- the synchronous slave communication device 4 includes a reception unit 41 that receives a plurality of frames, a reception time interval measurement unit 42 that measures a reception time interval between the plurality of frames, and a reception time interval that matches the transmission time interval. And a synchronization unit 43 that performs timing synchronization with the synchronization master communication device 2 based on the frame.
- the reception time interval is a time interval between the reception completion timing of one frame and the reception start timing of the next frame.
- FIG. 5 is a diagram illustrating a hardware configuration of the synchronous slave communication device of the communication system according to the first embodiment.
- the synchronous slave communication device 4 includes a receiving unit 41, a CPU 44, and a storage unit 45.
- the receiving unit 41, the CPU 44, and the storage unit 45 are connected via a bus B3.
- the receiving unit 41 is a physical layer circuit that bears the physical layer that is the first layer of the OSI reference model.
- the receiver 41 is connected to the hub 3 via the cable C2.
- the storage unit 45 stores a reception time interval measurement program 46 and a synchronization program 47.
- the storage unit 45 is exemplified by a flash memory (registered trademark).
- the reception time interval measurement program 46 is a program for measuring reception time intervals between a plurality of frames.
- the reception time interval measurement unit 42 that measures reception time intervals between a plurality of frames is realized.
- the synchronization program 47 is a program for performing timing synchronization with the synchronization master communication device 2 based on a plurality of frames when the reception time interval matches the transmission time interval.
- the synchronization unit 43 that performs timing synchronization with the synchronization master communication device 2 is realized based on a plurality of frames.
- FIG. 6 is a flowchart of a process performed by the synchronization master communication device of the communication system according to the first embodiment.
- the synchronization master communication device 2 starts the process shown in FIG.
- step S100 the frame generation unit 21 generates a synchronization signal for timing synchronization.
- the synchronization signal is exemplified by a signal at the reference time of the synchronization master communication device 2 that is a reference for timing synchronization.
- the synchronization slave communication device 4 can perform timing synchronization by setting the time obtained by adding the communication delay time to the synchronization signal to the timing at which the frame is received from the synchronization master communication device 2.
- step S102 the frame generation unit 21 generates a plurality of frames F1 and frames F2.
- the frame generation unit 21 generates the frames F1 and F2 so that the transmission time interval between the frames F1 and F2 is shorter than the time required for transmission of the minimum frame in the communication physical layer.
- FIG. 7 is a diagram illustrating a format of a frame transmitted and received by the communication system according to the first embodiment.
- the frame F1 and the frame F2 include a destination MAC address field 52, a transmission source MAC address field 53, a type field 54, a data field 55, and an FCS (Frame Check Sequence) field 56.
- the destination MAC address field 52 is 6 bytes long and stores the MAC address of the synchronous slave communication device 4.
- the source MAC address field 53 is 6 bytes long, and stores the MAC address of the synchronization master communication device 2.
- the type field 54 stores a bit string that specifies a protocol higher than the physical layer of communication.
- the data field 55 has a variable length from 46 bytes to 1500 bytes, and stores data to be transmitted.
- the frame generation unit 21 stores the synchronization signal generated in step S100 in the data field 55 of the frame F1.
- the synchronization master communication device 2 may send a synchronization signal to the synchronization slave communication device 4 in advance before starting the processing shown in FIG.
- the transmission time interval T0 measured by the transmission time interval measurement unit 22 is stored.
- the FCS field 56 has a length of 4 bytes and stores a bit string for checking whether there is a transmission error in the frame F1 or the frame F2.
- a CRC Cyclic Redundancy Check
- the frame length of the frames F1 and F2 is a minimum of 64 bytes and a maximum of 1518 bytes.
- the transmission time interval measuring unit 22 measures the transmission time interval T0 between the frame F1 and the frame F2 in step S104.
- the transmission time interval measuring unit 22 stores the measured transmission time interval T0 in the data field 55 of the frame F2.
- step S106 the transmission unit 23 transmits the frame F1 and the frame F2 at the transmission time interval T0, and ends the process.
- step S ⁇ b> 106 executed by the transmission unit 23 is described after step S ⁇ b> 104 executed by the transmission time interval measurement unit 22. However, actually, the transmission time interval measurement unit 22 and the transmission unit 23 operate in parallel.
- the transmission time interval measurement unit 22 can measure the transmission time interval T0 between the frames F1 and F2 by monitoring the transmission status of the frames F1 and F2 of the transmission unit 23.
- the transmission time interval measuring unit 22 stores the measured transmission time interval T0 in the data field 55 of the frame F2.
- FIG. 8 is a flowchart of a process performed by the synchronous slave communication device of the communication system according to the first embodiment.
- the receiving unit 41 receives the frame F1 and the frame F2 from the hub 3 in step S200.
- the reception time interval measurement unit 42 measures the reception time interval T between the frame F1 and the frame F2 in step S202.
- step S204 the synchronization unit 43 determines whether the reception time interval T matches the transmission time interval T0 stored in the data field 55 of the frame F2. If the synchronization unit 43 determines that the reception time interval T matches the transmission time interval T0 (Yes in step S204), the synchronization unit 43 advances the process to step S206. If the synchronization unit 43 determines that the reception time interval T does not match the transmission time interval T0 (No in step S204), the synchronization unit 43 ends the process.
- step S206 the synchronization unit 43 performs timing synchronization with the synchronization master communication device 2 based on the frame F1 and the frame F2.
- FIG. 9 is a diagram illustrating a first timing example of communication of the communication system according to the first embodiment.
- Synchronization master communication apparatus 2 at a timing t 0, it starts transmitting to the hub 3 of the frame F1.
- Hub 3 After starting the reception of frame F1 from the synchronization master communication apparatus 2, at timing t 1, starts to transfer to the synchronous slave communication apparatus 4 of the frame F1.
- Synchronization slave communication device 4 at the timing t 2 starts receiving the frame F1 from the hub 3.
- Synchronization master communication apparatus 2 at the timing t 3, and terminates the transmission to the hub 3 of the frame F1.
- Hub 3 when finished the reception of the frame F1 from the synchronization master communication apparatus 2, at a timing t 4, and terminates the transfer to the synchronous slave communication apparatus 4 of the frame F1.
- Synchronization slave communication device 4 at the timing t 5, and terminates the reception of the frame F1 from the hub 3.
- Synchronization master communication apparatus 2 at the timing t 6 after the transmission time interval T0 from the timing t 3, begins to transmit to the hub 3 of the frame F2.
- the transmission time interval T0 is shorter than the time required for transmitting the minimum frame.
- Communication device 5 or the communication device 6 does not transmit a frame, if a collision or an interrupt is generated to the frame F1 and the frame F2, the delay in the network is constant, between the timing t 4 and time t 7 Is equal to the transmission time interval T0.
- Synchronization slave communication device 4 at the timing t 8 starts receiving a frame F2 from the hub 3.
- Communication device 5 or the communication device 6 does not transmit a frame, if a collision or an interrupt is generated to the frame F1 and the frame F2, the delay in the network is constant, between the timing t 5 and the timing t 8 Is equal to the transmission time interval T0.
- Synchronization master communication apparatus 2 at a timing t 9, and terminates the transmission to the hub 3 of the frame F2.
- Hub 3 when finished the reception of the frame F2 from the synchronization master communication apparatus 2, at a timing t 10, and terminates the transfer to the synchronous slave communication apparatus 4 of the frame F2.
- Synchronization slave communication device 4 at the timing t 11, and terminates the reception of the frame F2 from the hub 3.
- the synchronization unit 43 of the synchronization slave communication device 4 performs timing synchronization.
- the reception time interval T is between the timing t 5 and the timing t 8 is the transmission time stored in the data field 55 of the frame F2 determined to match the interval T0, based on the synchronization signals stored in the data field 55 of the communication delay time Td and the frame F1 between timing t 0 and time t 2, performs timing synchronization.
- the reference time is a synchronization signal that is stored in the data field 55 of frame F1, a time obtained by adding a communication delay time Td, at the timing t 2 Set to the time of the synchronous slave communication device 4.
- the communication device 5 or The communication device 6 does not transmit a frame, and no collision or interruption with the frames F1 and F2 occurs. Therefore, the timing t 0, the timing t 2 to synchronize the slave communication apparatus 4 starts receiving a frame F1, the communication delay time Td between a constant.
- the synchronous slave communication device 4 can perform timing synchronization with high accuracy.
- FIG. 10 is a diagram illustrating a second timing example of communication of the communication system according to the first embodiment.
- Synchronization master communication apparatus 2 at a timing t 20, starts to transmit to the hub 3 of the frame F1.
- Hub 3 at the timing t 20 is performed to forward frames C from the communication device 5 to the communication device 6. That is, a collision between the frame C and the frame F1 occurs.
- the hub 3 at the timing t 20 can not initiate a transfer to a synchronous slave communication apparatus 4 of the frame F1.
- Synchronization master communication apparatus 2 at a timing t 23, and terminates the transmission to the hub 3 of the frame F1.
- Synchronization master communication apparatus 2 at a timing t 24 after the transmission time interval T0 from the timing t 23, starts to transmit to the hub 3 of the frame F2.
- Synchronization slave communication device 4 at the timing t 26, and terminates the reception of the frame F1 from the hub 3.
- the hub 3 at the timing t 26 starts to transfer to the synchronous slave communication apparatus 4 of the frame F2.
- the timing t 25 to the hub 3 has finished the transfer of frame F1
- the transfer time interval T between the timing t 26 to the hub 3 begins forwarding a frame F2
- the transmission time interval T0 is shorter than the transmission time interval T0.
- the timing t 26 to synchronize the slave communication apparatus 4 ends the reception of the frame F1
- the timing t 27 to synchronize the slave communication apparatus 4 starts receiving a frame F2
- Synchronization master communication apparatus 2 at a timing t 28, and terminates the transmission to the hub 3 of the frame F2.
- Synchronization slave communication device 4 at the timing t 30, and terminates the reception of the frame F2 from the hub 3.
- the hub 3 is synchronous master communication apparatus 2 at the timing t 20 to start sending the frame F1, is performed to forward frames C from the communication device 5 to the communication device 6. Therefore, a timing t 20, the timing t 23 to synchronize the slave communication apparatus 4 starts receiving a frame F1, the communication delay time Td between, than the communication delay time Td of the first timing example shown in FIG. 9 It will be long.
- Impact of the hub 3 is performing the transfer of frames C from the communication device 5 at the timing t 20 to the communication device 6, and that the communication delay time Td is longer than the first timing example, the reception time interval T is shorter than in the first timing example. Therefore, in the second timing example, the synchronization slave communication device 4 cannot perform timing synchronization with high accuracy.
- the synchronization slave communication device 4 is consistent with the transmission time interval T0 of the reception time interval T is stored in the data field 55 of frame F2 between timing t 26 and timing t 27 It can be determined that the timing synchronization cannot be performed with high accuracy. Therefore, in the second timing example, the synchronous slave communication device 4 does not perform timing synchronization.
- FIG. 11 is a diagram of a third timing example of communication of the communication system according to the first embodiment.
- Synchronization master communication apparatus 2 at a timing t 40, starts to transmit to the hub 3 of the frame F1.
- Hub 3 at the timing t 40 is performed to forward frames C1 from the communication device 5 to the communication device 6. That is, a collision between the frame C1 and the frame F1 occurs.
- the hub 3 at the timing t 40 can not initiate a transfer to a synchronous slave communication apparatus 4 of the frame F1.
- Synchronization master communication apparatus 2 at a timing t 43, and terminates the transmission to the hub 3 of the frame F1.
- Synchronization master communication apparatus 2 at a timing t 45 after the transmission time interval T0 from the timing t 43, starts to transmit to the hub 3 of the frame F2.
- Synchronization slave communication device 4 at the timing t 47, and terminates the reception of the frame F1 from the hub 3.
- Hub 3 at the timing t 47, to initiate a transfer from the communication device 5 to the communication device 6 of a frame C2 received. That is, an interrupt for the frame C2 occurs between the frames F1 and F2.
- the timing t 46 to the hub 3 has finished the transfer of frame F1
- the transfer time interval T between the timing t 50 to the hub 3 begins forwarding a frame F2
- the transmission time interval T0 is longer than the transmission time interval T0.
- Synchronization master communication apparatus 2 at a timing t 48, and ends the transmission of the frame F2.
- Hub 3 at the timing t 50 starts to transfer to the synchronous slave communication apparatus 4 of the frame F2.
- Synchronization slave communication device 4 at the timing t 51 starts receiving a frame F2 from the hub 3.
- the reception time interval T between the timing t 47 when the synchronization slave communication device 4 ends the reception of the frame F1 and the timing t 51 when the synchronization slave communication device 4 starts the reception of the frame F2 is a transmission time interval. It becomes longer than T0.
- Synchronization slave communication device 4 at the timing t 53, and terminates the reception of the frame F2 from the hub 3.
- the hub 3 is synchronous master communication apparatus 2 at the timing t 40 to start sending the frame F1, is performed to forward frames C1 from the communication device 5 to the communication device 6. Therefore, a timing t 40, the timing t 44 to synchronize the slave communication apparatus 4 starts receiving a frame F1, the communication delay time Td between, than the communication delay time Td of the first timing example shown in FIG. 9 It will be long. Therefore, in the third timing example, the synchronization slave communication device 4 cannot perform timing synchronization with high accuracy.
- the reception time interval T may coincide with the transmission time interval T0.
- the synchronization master communication device 2 transmits the frames F1 and F2 at a transmission time interval T0 that is shorter than the time required for transmitting the minimum frame. Therefore, even if the frame C2 is the minimum frame, the reception time interval T is always longer than the transmission time interval T0.
- the synchronization slave communication device 4 the reception time interval T between the timing t 47 and timing t 51 matches a transmission time interval T0 stored in the data field 55 of the frame F2 By determining that it is not, it can be determined that timing synchronization cannot be performed with high accuracy. Therefore, in the third timing example, the synchronous slave communication device 4 does not perform timing synchronization.
- the communication system 1 performs timing synchronization only when the timing synchronization illustrated in the first timing example can be performed with high accuracy, and illustrated in the second and third timing examples. If timing synchronization cannot be performed with high accuracy, timing synchronization is not performed.
- the communication system 1 can improve the accuracy of timing synchronization.
- the synchronization slave communication device 4 performs timing synchronization with the synchronization master communication device 2, but the hub 3 can also perform timing synchronization with the synchronization master communication device 2.
- FIG. 12 is a diagram illustrating a hardware configuration of the hub of the communication system according to the first embodiment.
- the hub 3 includes communication units 31-1, 31-2, 31-3, and 31-4, a CPU 32, and a storage unit 33.
- the communication units 31-1, 31-2, 31-3 and 31-4, the CPU 32, and the storage unit 33 are connected via a bus B2.
- Each of the communication units 31-1, 31-2, 31-3, and 31-4 is a physical layer circuit that bears the physical layer that is the first layer of the OSI reference model.
- the communication unit 31-1 is connected to the synchronization master communication device 2 via the cable C1.
- the communication unit 31-2 is connected to the synchronous slave communication device 4 via the cable C2.
- the communication unit 31-3 is connected to the communication device 5 via the cable C3.
- the communication unit 31-4 is connected to the communication device 6 via the cable C4.
- the storage unit 33 stores a transfer program 35, a reception time interval measurement program 46, and a synchronization program 47.
- the storage unit 33 is exemplified by a flash memory (registered trademark).
- the transfer program 35 refers to the MAC address stored in the destination MAC address field of the frame received by the communication unit 31-1, 31-2, 31-3, or 31-4, and sets the received frame as the destination.
- the transfer unit 34 that transfers the frame received by the communication unit 31-1, 31-2, 31-3, or 31-4 to the destination communication device is realized.
- the reception time interval measurement unit 42 that measures reception time intervals between a plurality of frames is realized.
- the synchronization unit 43 that performs timing synchronization with the synchronization master communication device 2 is realized based on a plurality of frames.
- the hub 3 can perform timing synchronization with the synchronization master communication device 2 by the above configuration.
- the configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.
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Abstract
Description
図1は、実施の形態1にかかる通信システムの構成を示す図である。
Claims (7)
- 最小フレームの送信に要する時間よりも短い送信時間間隔で複数のフレームを送信する第1の通信装置と、
受信した前記複数のフレームの受信時間間隔が前記送信時間間隔と一致したら、前記複数のフレームに基づいて、前記第1の通信装置とのタイミング同期を行う第2の通信装置と、
を備えることを特徴とする通信システム。 - 前記送信時間間隔は、1つのフレームの送信完了タイミングと、次のフレームの送信開始タイミングと、の間の時間間隔であり、
前記受信時間間隔は、1つのフレームの受信完了タイミングと、次のフレームの受信開始タイミングと、の間の時間間隔である
ことを特徴とする請求項1に記載の通信システム。 - 前記第1の通信装置は、
前記複数のフレームを生成するフレーム生成部と、
前記送信時間間隔を測定して前記フレームに格納するフレーム間隔測定部と、
前記複数のフレームを前記送信時間間隔で送信する送信部と、
を備えることを特徴とする請求項1に記載の通信システム。 - 前記第2の通信装置は、
前記複数のフレームを受信する受信部と、
前記受信時間間隔を測定するフレーム間隔測定部と、
前記受信時間間隔が前記送信時間間隔と一致したら、前記複数のフレームに基づいて、前記第1の通信装置とのタイミング同期を行う同期部と、
を備えることを特徴とする請求項1に記載の通信システム。 - 最小フレームを送信する時間よりも短い送信時間間隔で複数のフレームを送信する他の通信装置から、前記複数のフレームを受信し、前記複数のフレームの受信時間間隔が前記送信時間間隔と一致したら、前記複数のフレームに基づいて、前記他の通信装置とのタイミング同期を行うことを特徴とする通信装置。
- 最小フレームを送信する時間よりも短い送信時間間隔で複数のフレームを他の通信装置へ送信する通信装置であって、
前記他の通信装置は、前記複数のフレームを受信し、前記複数のフレームの受信時間間隔が前記送信時間間隔と一致したら、前記複数のフレームに基づいて、前記通信装置とのタイミング同期を行うことを特徴とする通信装置。 - 第1の通信装置と、前記第1の通信装置と通信する第2の通信装置と、を備える通信システムで実行される方法であって、
前記第1の通信装置が、最小フレームの送信に要する時間よりも短い送信時間間隔で複数のフレームを送信するステップと、
前記第2の通信装置が、受信した前記複数のフレームの受信時間間隔が前記送信時間間隔と一致したら、前記複数のフレームに基づいて、前記第1の通信装置とのタイミング同期を行うステップと、
を備えることを特徴とする通信方法。
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