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WO2020188703A1 - Time synchronization device, communication system, time synchronization method, and time synchronization program - Google Patents

Time synchronization device, communication system, time synchronization method, and time synchronization program Download PDF

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Publication number
WO2020188703A1
WO2020188703A1 PCT/JP2019/011215 JP2019011215W WO2020188703A1 WO 2020188703 A1 WO2020188703 A1 WO 2020188703A1 JP 2019011215 W JP2019011215 W JP 2019011215W WO 2020188703 A1 WO2020188703 A1 WO 2020188703A1
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Prior art keywords
unit
reception monitoring
message
time synchronization
request message
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PCT/JP2019/011215
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French (fr)
Japanese (ja)
Inventor
浩司 柴田
隆二 澤井
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三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to JP2019545379A priority Critical patent/JP6612006B1/en
Priority to CN201980093990.9A priority patent/CN113574827A/en
Priority to PCT/JP2019/011215 priority patent/WO2020188703A1/en
Publication of WO2020188703A1 publication Critical patent/WO2020188703A1/en

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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

Definitions

  • the present invention relates to a time synchronization device for performing time synchronization, a communication system, a time synchronization method, and a time synchronization program.
  • Non-Patent Document 1 a time synchronization technology that synchronizes the time of multiple devices on the network in a master-slave system consisting of multiple devices, such as IEEE (The Institute of Electrical and Electronics Engineers) 1588. Yes (Non-Patent Document 1).
  • IEEE1588 stipulates that the communication delay time of the propagation path between devices is measured and the time is synchronized. Each device performs measurement of the communication delay time of the propagation path at a fixed cycle.
  • the Requester which is a device requesting the delay measurement
  • the Responder which is a device that receives the DelayReq message
  • stores the time stamp at the time of receiving the DelayReq in the DelayResp message and the Requester. It is carried out by sending to.
  • IEEE Std 1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems
  • one Responder transmits a plurality of Requesters that perform propagation delay time measurement. Receives a plurality of DelayReq messages.
  • the Responder needs to hold a plurality of time stamps at the time of receiving the DelayReq message for each source, but the number of time stamps held is limited.
  • the Responder sends a DelayResp message only to the Requester who was able to retain the time stamp. Therefore, in a certain cycle, there is a problem that the DelayResp message cannot be received by the Requester and the propagation delay time measurement cannot be completed.
  • each Requester transmits a DelayReq message at regular intervals. Therefore, there is a possibility that a certain requester may not be able to receive the DelayResp message even in the next cycle in which the DelayResp message could not be received, and there is a problem that the propagation delay time measurement cannot be completed and the time cannot be synchronized.
  • the present invention has been made in view of the above, and an object of the present invention is to obtain a time synchronization device capable of time synchronization even in a communication system in which a plurality of time synchronization devices are connected to a relay device.
  • the first device has a propagation delay time with and from the second device via a relay device to which a plurality of first devices can be connected. It is a time synchronization device which is the first device for performing measurement.
  • the time synchronization device has a transmission unit that transmits a request message for measuring the propagation delay time to the second device, a reception unit that receives a response message from the second device that is a response to the request message, and a reception monitoring timer.
  • the reception monitoring timer is activated, and if the reception monitoring timer times out before the receiving unit receives the response message, the receiving monitoring unit instructs the transmitting unit to retransmit the request message. And.
  • the time-out setting value of the reception monitoring timer is tO
  • the number of connections of the time synchronization device connected to the relay device is N
  • the transmission cycle of the request message of the transmission unit is T
  • tO ⁇ T / N the transmission cycle of the request message of the transmission unit
  • the time synchronization device has an effect that time synchronization can be performed even in a communication system in which a plurality of time synchronization devices are connected to a relay device.
  • the figure which shows the configuration example of the synchronous slave which concerns on Embodiment 1. A flowchart showing a monitoring operation of the reception monitoring unit of the synchronous slave according to the first embodiment.
  • a sequence diagram showing the timing of sending and receiving messages of each device when the synchronous slave measures the propagation delay time.
  • the figure which shows the configuration example of the synchronous slave which concerns on Embodiment 2. A flowchart showing an operation in which the reception monitoring unit of the synchronous slave according to the second embodiment calculates a timeout set value.
  • FIG. 1 is a diagram showing a configuration example of a communication system 4 according to a first embodiment of the present invention.
  • the communication system 4 includes a synchronization master 1 having a reference time, a switching hub 2 that does not support IECEE1588, and synchronization slaves 3a and 3b that synchronize with the synchronization master 1.
  • the synchronization slaves 3a and 3b serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronization master 1
  • the synchronization master 1 serves as a responder.
  • the synchronization master 1 performs the same operation as the standard of IECEE1588.
  • the synchronization master 1 When the synchronization master 1 receives the DeliveryReq message for measuring the propagation delay time transmitted from the synchronization slaves 3a and 3b, the synchronization master 1 transmits a DeliveryResp message which is a response of the DeliveryReq message.
  • the switching hub 2 that does not support IECEE1588 is a relay device that performs frame transfer according to the destination address of the received frame.
  • the switching hub 2 can also be connected to three or more synchronous slaves.
  • the synchronization slaves 3a and 3b measure the propagation delay time with the synchronization master 1 via the switching hub 2.
  • the Requester may be referred to as a first device, and the Responder may be referred to as a second device. Further, the first device which is a requester may be referred to as a time synchronization device.
  • FIG. 2 is a diagram showing a configuration example of the communication system 4a according to the first embodiment.
  • the communication system 4a includes a synchronization master 1, a switching hub 2, a synchronization slave 3c, and synchronization slaves 3a and 3b that synchronize with the synchronization slave 3c.
  • the synchronous slaves 3a and 3b serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronous slave 3c
  • the synchronous slave 3c serves as a responder.
  • the synchronization slave 3c can measure the propagation delay time of the propagation path to and from the synchronization master 1 according to the procedure of IECEE1588.
  • the communication system 4 shown in FIG. 1 will be described as an example.
  • FIG. 3 is a diagram showing a configuration example of the synchronous slave 3a according to the first embodiment. Since the synchronous slaves 3a and 3b have the same configuration, the synchronous slave 3a will be described as an example.
  • the synchronization slave 3a includes a frame reception unit 31, a frame transmission unit 32, a time synchronization unit 33, and a reception monitoring unit 34.
  • the frame receiving unit 31 is a receiving unit having a frame analysis unit 310.
  • the frame analysis unit 310 analyzes the frame received from the switching hub 2. When the received frame is a message related to time synchronization, the frame analysis unit 310 outputs the received data included in the received frame to the time synchronization unit 33.
  • the frame analysis unit 310 notifies the reception monitoring unit 34 that the DeliveryResp message has been received when it receives the DeliveryResp message addressed to the synchronization slave 3a among the messages related to time synchronization.
  • the DelayResp message is a response message to the DelayReq message received by the sync master 1 which is the responder from the sync slave 3a which is the requester.
  • the DelayResp message may be referred to as a response message.
  • the DelayReq message is a message in which the synchronous slave 3a, which is the requester, requests the synchronization master 1, which is the responder, to measure the propagation delay time.
  • the DelayReq message may be referred to as a request message.
  • the frame analysis unit 310 holds the time stamp value at the time of reception when it receives the DelayReq message among the messages related to time synchronization.
  • the frame analysis unit 310 notifies the frame transmission unit 32 of the retained time stamp value, the source information of the DelayReq message indicating the requester which is the information included in the DelayReq message and is the source, and the DelayReq message. To do.
  • the frame transmission unit 32 is a transmission unit having a transmission cycle timer 320.
  • the transmission cycle timer 320 is a timer that times out in the transmission cycle T, which is the cycle in which the frame transmission unit 32 transmits the DelayReq message.
  • the frame transmission unit 32 transmits a DelayReq message to the switching hub 2 at the time-out when the transmission cycle timer 320 times out in the transmission cycle T.
  • the frame transmission unit 32 notifies the time synchronization unit 33 and the reception monitoring unit 34 that the DelayReq message has been transmitted. Further, when the frame transmission unit 32 receives an instruction to retransmit the DeliveryReq message from the reception monitoring unit 34, the frame transmission unit 32 transmits the DeliveryReq message and restarts the transmission cycle timer 320.
  • the frame transmitting unit 32 is notified by the frame receiving unit 31 that the time stamp value, the source information of the DelayReq message, and the DelayReq message have been received, and the time stamp value and the DelayReq are notified.
  • the source information of the message is stored in the DelayResp message and transmitted.
  • the time synchronization unit 33 has a time counter 330.
  • the time synchronization unit 33 records the time counter value of the time counter 330 at the time of acquisition.
  • the frame transmission unit 32 notifies that the DelayReq message has been transmitted
  • the time synchronization unit 33 records the time counter value of the time counter 330 at the time of notification.
  • the time synchronization unit 33 calculates the time of the synchronization master 1 using the recorded time counter value and the reception data acquired from the frame reception unit 31, and synchronizes the time counter 330 with the synchronization master 1.
  • the time when the frame transmission unit 32 transmits the DelayReq message is t1
  • the time when the synchronization master 1 receives the DelayReq message is t2
  • the time when the synchronization master 1 transmits the DelayResp message is t3
  • the frame reception unit 31 transmits the DelayResp message.
  • t4 be the time of reception.
  • the synchronization slave 3a can acquire the information of t2 and t3 by including the information of t2 and t3 in the DelayResp message by the synchronization master 1.
  • the time synchronization unit 33 calculates the one-way communication delay time from ((t4-t3) + (t2-t1)) / 2, and calculates the time of the synchronization master 1 using the calculated one-way communication delay time.
  • the time counter 330 is synchronized with the synchronization master 1.
  • the reception monitoring unit 34 has a reception monitoring timer 340.
  • the reception monitoring timer 340 is a timer for monitoring the reception of the DelayResp message.
  • the reception monitoring unit 34 activates the reception monitoring timer 340 when the frame transmission unit 32 transmits a DelayReq message. If the reception monitoring timer 340 times out before the frame receiving unit 31 receives the DelayResp message, the reception monitoring unit 34 instructs the frame transmitting unit 32 to retransmit the DelayReq message.
  • the set value tO is a value at which tO ⁇ T / N.
  • the user who manages the communication system 4 sets in the reception monitoring unit 34 the result of calculating a value such that tO ⁇ T / N in advance.
  • FIG. 4 is a flowchart showing a monitoring operation of the reception monitoring unit 34 of the synchronous slave 3a according to the first embodiment. Since the synchronous slaves 3a and 3b perform the same operation, the synchronous slave 3a will be described as an example.
  • the reception monitoring unit 34 confirms whether or not there is a notification that the DelayReq message has been transmitted from the frame transmission unit 32 (step S11). When there is no notification from the frame transmission unit 32 that the DelayReq message has been transmitted (step S11: No), the reception monitoring unit 34 waits until the frame transmission unit 32 notifies that the DelayReq message has been transmitted. The reception monitoring unit 34 activates the reception monitoring timer 340 (step S12) when the frame transmission unit 32 notifies that the DelayReq message has been transmitted (step S11: Yes).
  • the reception monitoring unit 34 When the reception monitoring unit 34 activates the reception monitoring timer 340, the reception monitoring unit 34 confirms the timeout of the reception monitoring timer 340 (step S13). When the reception monitoring timer 340 times out (step S13: Yes), the reception monitoring unit 34 instructs the frame transmission unit 32 to retransmit the DelayReq message (step S14).
  • the reception monitoring unit 34 confirms whether or not there is a notification that the DelayResp message has been received from the frame receiving unit 31 (step S15).
  • the reception monitoring unit 34 receives a notification from the frame receiving unit 31 that the DeliveryResp message has been received (step S15: Yes)
  • the reception monitoring unit 34 stops and resets the reception monitoring timer 340 (step S16).
  • the reception monitoring unit 34 returns to the operation of step S13 and confirms the timeout of the reception monitoring timer 340 (step S13).
  • FIG. 5 is a sequence diagram showing the timing of transmitting and receiving messages of each device when the synchronous slaves 3a and 3b measure the propagation delay time in the communication system 4 according to the first embodiment.
  • the synchronization master 1 which is a Responder can hold only one time stamp value when receiving the DelayReq message.
  • the synchronous slaves 3a and 3b which are requesters, transmit a DelayReq message in order to measure the propagation delay time.
  • the transmission cycle timer 320 and the reception monitoring timer 340 are activated (step S21).
  • the DelayReq message transmitted by the synchronous slave 3a is referred to as the DelayReq message 3a
  • the DelayReq message transmitted by the synchronous slave 3b is referred to as the DelayReq message 3b
  • the synchronous master 1 transmits to the synchronous slave 3a.
  • the DelayResp message is referred to as a DelayResp message 3a
  • the DelayResp message transmitted by the synchronization master 1 to the synchronization slave 3b is referred to as a DelayResp message 3b.
  • the synchronization master 1 which is a receiver receives the DelayReq message 3b from the synchronization slave 3b first, and retains the time stamp at the time of reception.
  • the synchronization master 1 ignores the DelayReq message 3a from the synchronization slave 3a received immediately afterwards.
  • the synchronization master 1 transmits a DelayResp message 3b to the synchronization slave 3b (step S22).
  • the synchronous slave 3b stops and resets the reception monitoring timer 340 (step S23).
  • the synchronous slave 3a retransmits the DelayReq message 3a due to the timeout of the reception monitoring timer 340, and restarts the transmission cycle timer 320 (step S24).
  • the synchronization master 1 receives the DelayReq message 3a from the synchronization slave 3a and retains the time stamp at the time of reception.
  • the synchronization master 1 transmits a DelayResp message 3a to the synchronization slave 3a (step S25).
  • the synchronous slave 3a receives the DelayResp message 3a, the synchronous slave 3a stops and resets the reception monitoring timer 340 (step S26).
  • the synchronous slave 3b transmits a DelayReq message 3b when the transmission cycle timer 320 times out.
  • the synchronous slave 3b activates the transmission cycle timer 320 and the reception monitoring timer 340 (step S27).
  • the synchronization master 1 receives the DelayReq message 3b from the synchronization slave 3b and retains the time stamp at the time of reception.
  • the synchronization master 1 transmits a DelayResp message 3b to the synchronization slave 3b (step S28).
  • the synchronous slave 3b receives the DelayResp message 3b, the synchronous slave 3b stops and resets the reception monitoring timer 340 (step S29).
  • the synchronous slave 3a transmits a DelayReq message 3a when the transmission cycle timer 320 times out.
  • the synchronous slave 3a activates the transmission cycle timer 320 and the reception monitoring timer 340 (step S30).
  • the synchronization master 1 receives the DelayReq message 3a from the synchronization slave 3a and retains the time stamp at the time of reception.
  • the synchronization master 1 transmits a DelayResp message 3a to the synchronization slave 3a (step S31).
  • the synchronous slave 3a receives the DelayResp message 3a
  • the synchronous slave 3a stops and resets the reception monitoring timer 340 (step S32).
  • the operations of steps S27 to S32 are repeated thereafter.
  • the synchronous slave 3a transmits the DelayReq message due to the timeout of the reception monitoring timer 340
  • the synchronous slave 3a can transmit the DelayReq message without overlapping the transmission timing with the synchronous slave 3b waiting for the timeout of the transmission cycle timer 320. it can. Since the synchronization slave 3a does not overlap with the synchronization slave 3b in the transmission timing of the DelayReq message, the propagation delay time measurement can be completed and the time synchronization can be performed.
  • the propagation delay time measurement is not completed by setting tO ⁇ T / N.
  • the transmission timing of the DelayReq message does not overlap with the completed synchronous slave.
  • all the synchronized slaves can complete the propagation delay time measurement, and the time synchronization can be performed.
  • FIG. 6 is a diagram showing an example of hardware that realizes the synchronous slave 3a according to the first embodiment.
  • the synchronous slave 3a can be realized by the processor 101, the storage device 102, and the communication interface 103 shown in FIG.
  • the processor 101 is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor)), system LSI (Large Scale Integration), or the like.
  • the storage device 102 includes a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), a hard disk drive, and the like.
  • the communication interface 103 is a processing circuit for the frame receiving unit 31 to receive the communication frame and the frame transmitting unit 32 to transmit the communication frame in the synchronous slave 3a, and is, for example, a network interface card.
  • the parts other than the functions realized by the communication interface 103 in the time synchronization unit 33, the reception monitoring unit 34, the frame reception unit 31 and the frame transmission unit 32 are the processors 101 for operating as each of these parts. Is realized by executing. Such a program is stored in the storage device 102 in advance. By reading and executing the above program from the storage device 102, the processor 101 performs parts other than the functions realized by the communication interface 103 in the time synchronization unit 33, the reception monitoring unit 34, the frame reception unit 31 and the frame transmission unit 32. Realize.
  • the above program may be provided to the user in a state of being stored in the storage device 102 in advance, or may be a recording medium readable by a computer or the like, for example, a CD (Compact Disc) -ROM, a DVD (Digital Versatile).
  • Disc) -It may be supplied to the user in a state of being written in a ROM or the like, and may be installed by the user in the storage device 102.
  • the synchronization slaves 3a and 3b that perform time synchronization monitor reception when transmitting the DelayReq message.
  • the timeout setting value of the reception monitoring timer 340 is tO
  • the number of connections of the synchronous slaves 3a and 3b connected to the switching hub 2 is N
  • the transmission cycle of the DelayReq message of the synchronous slaves 3a and 3b is T
  • tO ⁇ T / N the number of connections of the synchronous slaves 3a and 3b connected to the switching hub 2.
  • the synchronization slaves 3a and 3b If the synchronization slaves 3a and 3b do not receive the DelayResp message from the synchronization master 1 within the timeout set value tO, the synchronization slaves 3a and 3b retransmit the DelayReq message.
  • the propagation delay time can be measured by the transmitted DelayReq message
  • the synchronous slaves 3a and 3b will transmit the DelayReq message at intervals of the transmission cycle T from the time when the DelayReq message is retransmitted.
  • the synchronous slaves 3a and 3b can measure the propagation delay time even in the communication system 4 in which the synchronous slaves 3a and 3b, which are a plurality of requesters, are connected to the switching hub 2 which does not support the IEEE1588. Synchronization is possible.
  • Embodiment 2 the synchronous slave, which is a requester, counts the number of connections N and automatically calculates the timeout set value tO. A part different from the first embodiment will be described.
  • FIG. 7 is a diagram showing a configuration example of the communication system 4A according to the second embodiment.
  • the communication system 4A includes a synchronization master 1, a switching hub 2, and synchronization slaves 3Aa and 3Ab that synchronize with the synchronization master 1.
  • the synchronous slaves 3Aa and 3Ab serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronous master 1, and the synchronous master 1 serves as a responder.
  • FIG. 8 is a diagram showing a configuration example of the communication system 4Aa according to the second embodiment.
  • the communication system 4Aa includes a synchronization master 1, a switching hub 2, a synchronization slave 3Ac, and synchronization slaves 3Aa and 3Ab that synchronize with the synchronization slave 3Ac.
  • the synchronous slaves 3Aa and 3Ab serve as a requester for measuring the propagation delay time of the propagation path between the synchronous slaves 3Aa and 3Ab
  • the synchronous slave 3Ac serves as a responder.
  • the synchronization slave 3Ac can measure the propagation delay time of the propagation path to and from the synchronization master 1 according to the procedure of IECEE1588.
  • the communication system 4A shown in FIG. 7 will be described as an example.
  • FIG. 9 is a diagram showing a configuration example of the synchronous slave 3Aa according to the second embodiment. Since the synchronous slaves 3Aa and 3Ab have the same configuration, the synchronous slave 3Aa will be described as an example.
  • the synchronization slave 3Aa includes a frame reception unit 31A, a frame transmission unit 32, a time synchronization unit 33, and a reception monitoring unit 34A.
  • the frame receiving unit 31A is a receiving unit having a frame analysis unit 310A, a table management unit 311A, and a counter 312A.
  • the frame analysis unit 310A analyzes the frame received from the switching hub 2. When the received frame is a message related to time synchronization, the frame analysis unit 310A outputs the received data included in the received frame to the time synchronization unit 33. When the synchronous slave 3Aa is the Requester, the frame analysis unit 310A notifies the reception monitoring unit 34A that the DelayResp message has been received when it receives the DelayResp message addressed to the synchronous slave 3Aa among the messages related to time synchronization.
  • the frame analysis unit 310A When the frame analysis unit 310A receives the DelayReq message transmitted from the synchronization slave which is another requester among the messages related to time synchronization, the requester identification which is the information included in the DelayReq message and indicates the synchronization slave which is the source. Notify the information to the table management unit 311A.
  • the Requester identification information is, for example, a MAC (Media Access Control) address or the like.
  • the frame analysis unit 310A holds the time stamp value at the time of reception when it receives the DelayReq message among the messages related to time synchronization.
  • the frame analysis unit 310A notifies the frame transmission unit 32 of the retained time stamp value, the source information of the DelayReq message indicating the requester which is the information included in the DelayReq message and the source, and the fact that the DelayReq message has been received. To do.
  • the table management unit 311A registers the requester identification information notified from the frame analysis unit 310A in the requester table of the table management unit 311A.
  • the table management unit 311A counts up the counter 312A by 1 when the requester identification information is newly registered in the requester table.
  • the initial value of the counter value of the counter 312A is 1.
  • the table management unit 311A deletes the corresponding Requester identification information from the Requester table. Then, the counter 312A is counted down by one.
  • the frame analysis unit 310A or the table management unit 311A notifies the reception monitoring unit 34A of the counter value of the counter 312A.
  • the frame receiving unit 31A determines the number of connections N of the synchronous slaves that are the requesters connected to the switching hub 2 depending on the number of received DelayReq messages transmitted by the synchronous slaves that are other requesters. Count.
  • the reception monitoring unit 34A has a reception monitoring timer 340A and a timeout value setting unit 341A.
  • the timeout value setting unit 341A calculates the timeout setting value tO of the reception monitoring timer 340A by using the counter value of the counter 312A notified from the frame reception unit 31A. Specifically, the timeout value setting unit 341A calculates the timeout setting value tO of the reception monitoring timer 340A so that tO ⁇ T / N, where the counter value of the counter 312A is the number of connections N. The timeout value setting unit 341A notifies the reception monitoring timer 340A of the calculated timeout setting value tO of the reception monitoring timer 340A.
  • the reception monitoring timer 340A is a timer for monitoring the reception of the DelayResp message.
  • the timeout setting value tO of the reception monitoring timer 340A is the value notified from the timeout value setting unit 341A.
  • the reception monitoring unit 34A calculates the timeout set value tO using the number of connections N counted by the frame reception unit 31A and the transmission cycle T.
  • FIG. 10 is a flowchart showing an operation in which the reception monitoring unit 34A of the synchronous slave 3Aa according to the second embodiment calculates the timeout set value tO. Since the synchronous slaves 3Aa and 3Ab perform the same operation, the synchronous slave 3Aa will be described as an example.
  • the timeout value setting unit 341A acquires the counter value of the counter 312A from the frame reception unit 31A (step S41).
  • the timeout value setting unit 341A uses the counter value of the counter 312A as the number of connections N, the number of connections N, and the transmission cycle timer 320 of the frame transmission unit 32 uses the transmission cycle T, so that the timeout setting value is to ⁇ T / N.
  • Calculate toO step S42.
  • the timeout value setting unit 341A notifies the reception monitoring timer 340A of the calculated timeout setting value tO (step S43). Since the monitoring operation of the reception monitoring unit 34A using the timeout set value tO is the same as the monitoring operation of the reception monitoring unit 34 of the first embodiment shown in FIG. 4, detailed description thereof will be omitted.
  • the synchronous slave 3Aa is realized by the hardware configuration shown in FIG. 6, as in the synchronous slave 3a of the first embodiment.
  • the synchronous slaves 3Aa and 3Ab obtain the connection number N of the requesters connected to the switching hub 2 from the number of DelayReq messages received from the other synchronous slaves, and connect them. It was decided to calculate the timeout set value tO of the reception monitoring timer 340A using the number N. As a result, the synchronous slaves 3Aa and 3Ab can automatically calculate the timeout set value tO of the reception monitoring timer 340A. As a result, the user can easily operate the communication system 4A without calculating and changing the timeout setting value due to the difference in the configuration of the communication system 4A.
  • the configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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  • Computer Networks & Wireless Communication (AREA)
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Abstract

A time synchronization device in which a first device measures a propagation delay time, between the first device and a second device, via a relay device to which a plurality of the first device can be connected, the time synchronization device comprising: a frame transmission unit (32) for transmitting a propagation delay time measurement request message to the second device; a frame reception unit (31) for receiving a response message constituting a response to the request message; and a reception monitoring unit (34) that has a reception monitoring timer (340), starts the reception monitoring timer (340) when the frame transmission unit (32) transmits the request message, and instructs the frame transmission unit (32) to resend the request message if the reception monitoring timer (340) times out before the frame reception unit (31) receives the response message, wherein tO ≤ T/N when tO is a timeout setting value for the reception monitoring timer (340), N is the number of time synchronization devices connected to the relay device, and T is the transmission period of the request message of the frame transmission unit (32).

Description

時刻同期装置、通信システム、時刻同期方法および時刻同期プログラムTime sync device, communication system, time sync method and time sync program
　本発明は、時刻同期を行う時刻同期装置、通信システム、時刻同期方法および時刻同期プログラムに関する。 The present invention relates to a time synchronization device for performing time synchronization, a communication system, a time synchronization method, and a time synchronization program.
　従来、ネットワークで接続された複数の機器が連携して動作するシステムでは、複数の機器の制御タイミングを合わせるため、各機器の時刻を同期させることが必要である。機器間の時刻を同期させる規格として、ＩＥＥＥ（The　Institute　of　Electrical　and　Electronics　Engineers）１５８８のように、複数の機器から成るマスタスレーブシステムにおいて、ネットワーク上の複数の機器の時刻を同期させる時刻同期技術がある（非特許文献１）。 Conventionally, in a system in which a plurality of devices connected by a network operate in cooperation with each other, it is necessary to synchronize the time of each device in order to match the control timing of the plurality of devices. As a standard for synchronizing the time between devices, there is a time synchronization technology that synchronizes the time of multiple devices on the network in a master-slave system consisting of multiple devices, such as IEEE (The Institute of Electrical and Electronics Engineers) 1588. Yes (Non-Patent Document 1).
　ＩＥＥＥ１５８８では、機器間の伝搬路の通信遅延時間を計測し、時刻の同期を実施することが規定されている。伝搬路の通信遅延時間計測は、各機器が一定周期で実施する。伝搬路の通信遅延計測は、遅延計測を要求する機器であるＲｅｑｕｅｓｔｅｒが、ＤｅｌａｙＲｅｑメッセージを送信し、ＤｅｌａｙＲｅｑメッセージを受信した機器であるＲｅｓｐｏｎｄｅｒが、ＤｅｌａｙＲｅｓｐメッセージにＤｅｌａｙＲｅｑ受信時のタイムスタンプを格納してＲｅｑｕｅｓｔｅｒへ送信することなどによって実施される。 IEEE1588 stipulates that the communication delay time of the propagation path between devices is measured and the time is synchronized. Each device performs measurement of the communication delay time of the propagation path at a fixed cycle. In the communication delay measurement of the propagation path, the Requester, which is a device requesting the delay measurement, sends a DelayReq message, and the Responder, which is a device that receives the DelayReq message, stores the time stamp at the time of receiving the DelayReq in the DelayResp message and the Requester. It is carried out by sending to.
　しかしながら、ＩＥＥＥ１５８８に非対応のスイッチングハブが存在し、ＩＥＥＥ１５８８に非対応のスイッチングハブに複数のＲｅｑｕｅｓｔｅｒが接続されているシステムでは、１台のＲｅｓｐｏｎｄｅｒが、伝搬遅延時間計測を実施する複数のＲｅｑｕｅｓｔｅｒが送信するＤｅｌａｙＲｅｑメッセージを複数個受信する。Ｒｅｓｐｏｎｄｅｒは、ＤｅｌａｙＲｅｑメッセージ受信時のタイムスタンプを送信元ごとに複数個保持する必要があるが、タイムスタンプを保持する数には制限がある。Ｒｅｓｐｏｎｄｅｒは、タイムスタンプを保持することができたＲｅｑｕｅｓｔｅｒにのみＤｅｌａｙＲｅｓｐメッセージを送信する。そのため、ある周期では、ＲｅｑｕｅｓｔｅｒによってはＤｅｌａｙＲｅｓｐメッセージを受信できず、伝搬遅延時間計測を完了できない、という問題があった。また、各Ｒｅｑｕｅｓｔｅｒは、一定周期でＤｅｌａｙＲｅｑメッセージを送信する。そのため、あるＲｅｑｕｅｓｔｅｒは、ＤｅｌａｙＲｅｓｐメッセージを受信できなかった次の周期でもＤｅｌａｙＲｅｓｐメッセージを受信できない可能性があり、伝搬遅延時間計測を完了することができず時刻同期できない、という問題があった。 However, in a system in which a switching hub that does not support IECEE1588 exists and a plurality of requesters are connected to the switching hub that does not support IECEE1588, one Responder transmits a plurality of Requesters that perform propagation delay time measurement. Receives a plurality of DelayReq messages. The Responder needs to hold a plurality of time stamps at the time of receiving the DelayReq message for each source, but the number of time stamps held is limited. The Responder sends a DelayResp message only to the Requester who was able to retain the time stamp. Therefore, in a certain cycle, there is a problem that the DelayResp message cannot be received by the Requester and the propagation delay time measurement cannot be completed. In addition, each Requester transmits a DelayReq message at regular intervals. Therefore, there is a possibility that a certain requester may not be able to receive the DelayResp message even in the next cycle in which the DelayResp message could not be received, and there is a problem that the propagation delay time measurement cannot be completed and the time cannot be synchronized.
　本発明は、上記に鑑みてなされたものであって、複数の時刻同期装置が中継装置に接続された通信システムにおいても時刻同期可能な時刻同期装置を得ることを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to obtain a time synchronization device capable of time synchronization even in a communication system in which a plurality of time synchronization devices are connected to a relay device.
　上述した課題を解決し、目的を達成するために、本発明は、第１の装置が、複数の第１の装置を接続可能な中継装置を介して第２の装置との間で伝搬遅延時間計測を実施する第１の装置である時刻同期装置である。時刻同期装置は、第２の装置に伝搬遅延時間計測の要求メッセージを送信する送信部と、要求メッセージの応答である第２の装置からの応答メッセージを受信する受信部と、受信監視タイマを有し、送信部が要求メッセージを送信したときに受信監視タイマを起動し、受信部が応答メッセージを受信する前に受信監視タイマがタイムアウトした場合、送信部に要求メッセージの再送を指示する受信監視部と、を備える。受信監視タイマのタイムアウト設定値をｔＯ、中継装置に接続される時刻同期装置の接続数をＮ、送信部の要求メッセージの送信周期をＴとし、ｔＯ≦Ｔ／Ｎであることを特徴とする。 In order to solve the above-mentioned problems and achieve the object, in the present invention, the first device has a propagation delay time with and from the second device via a relay device to which a plurality of first devices can be connected. It is a time synchronization device which is the first device for performing measurement. The time synchronization device has a transmission unit that transmits a request message for measuring the propagation delay time to the second device, a reception unit that receives a response message from the second device that is a response to the request message, and a reception monitoring timer. Then, when the transmitting unit sends the request message, the reception monitoring timer is activated, and if the reception monitoring timer times out before the receiving unit receives the response message, the receiving monitoring unit instructs the transmitting unit to retransmit the request message. And. The time-out setting value of the reception monitoring timer is tO, the number of connections of the time synchronization device connected to the relay device is N, the transmission cycle of the request message of the transmission unit is T, and tO ≦ T / N.
　本発明にかかる時刻同期装置は、複数の時刻同期装置が中継装置に接続された通信システムにおいても時刻同期できる、という効果を奏する。 The time synchronization device according to the present invention has an effect that time synchronization can be performed even in a communication system in which a plurality of time synchronization devices are connected to a relay device.
実施の形態１に係る通信システムの構成例を示す図The figure which shows the configuration example of the communication system which concerns on Embodiment 1. 実施の形態１に係る通信システムの他の構成例を示す図The figure which shows the other configuration example of the communication system which concerns on Embodiment 1. 実施の形態１に係る同期スレーブの構成例を示す図The figure which shows the configuration example of the synchronous slave which concerns on Embodiment 1. 実施の形態１に係る同期スレーブの受信監視部の監視動作を示すフローチャートA flowchart showing a monitoring operation of the reception monitoring unit of the synchronous slave according to the first embodiment. 実施の形態１に係る通信システムにおいて、同期スレーブが伝搬遅延時間計測を行うときの、各装置のメッセージの送受信のタイミングを示すシーケンス図In the communication system according to the first embodiment, a sequence diagram showing the timing of sending and receiving messages of each device when the synchronous slave measures the propagation delay time. 実施の形態１に係る同期スレーブを実現するハードウェアの一例を示す図The figure which shows an example of the hardware which realizes the synchronous slave which concerns on Embodiment 1. 実施の形態２に係る通信システムの構成例を示す図The figure which shows the configuration example of the communication system which concerns on Embodiment 2. 実施の形態２に係る通信システムの他の構成例を示す図The figure which shows the other configuration example of the communication system which concerns on Embodiment 2. 実施の形態２に係る同期スレーブの構成例を示す図The figure which shows the configuration example of the synchronous slave which concerns on Embodiment 2. 実施の形態２に係る同期スレーブの受信監視部がタイムアウト設定値を算出する動作を示すフローチャートA flowchart showing an operation in which the reception monitoring unit of the synchronous slave according to the second embodiment calculates a timeout set value.
　以下に、本発明の実施の形態に係る時刻同期装置、通信システム、時刻同期方法および時刻同期プログラムを図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。 The time synchronization device, communication system, time synchronization method, and time synchronization program according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment.
実施の形態１．
　図１は、本発明の実施の形態１に係る通信システム４の構成例を示す図である。通信システム４は、基準となる時刻を持つ同期マスタ１と、ＩＥＥＥ１５８８に非対応のスイッチングハブ２と、同期マスタ１に同期する同期スレーブ３ａ，３ｂと、を備える。図１に示す通信システム４では、同期スレーブ３ａ，３ｂが同期マスタ１との間の伝搬路の伝搬遅延時間を計測するＲｅｑｕｅｓｔｅｒとなり、同期マスタ１がＲｅｓｐｏｎｄｅｒとなる。同期マスタ１は、ＩＥＥＥ１５８８の規格と同一の動作を実施する。同期マスタ１は、同期スレーブ３ａ，３ｂから送信された伝搬遅延時間計測のＤｅｌａｙＲｅｑメッセージを受信した場合、ＤｅｌａｙＲｅｑメッセージの応答であるＤｅｌａｙＲｅｓｐメッセージを送信する。ＩＥＥＥ１５８８非対応のスイッチングハブ２は、受信するフレームの宛先アドレスに従い、フレーム転送を実施する中継装置である。スイッチングハブ２は、３つ以上の同期スレーブと接続することも可能である。同期スレーブ３ａ，３ｂは、スイッチングハブ２を介して同期マスタ１との間で伝搬遅延時間計測を実施する。以降の説明において、Ｒｅｑｕｅｓｔｅｒを第１の装置と称し、Ｒｅｓｐｏｎｄｅｒを第２の装置と称することがある。また、Ｒｅｑｕｅｓｔｅｒである第１の装置を時刻同期装置と称することがある。 Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a communication system 4 according to a first embodiment of the present invention. The communication system 4 includes a synchronization master 1 having a reference time, a switching hub 2 that does not support IECEE1588, and synchronization slaves 3a and 3b that synchronize with the synchronization master 1. In the communication system 4 shown in FIG. 1, the synchronization slaves 3a and 3b serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronization master 1, and the synchronization master 1 serves as a responder. The synchronization master 1 performs the same operation as the standard of IECEE1588. When the synchronization master 1 receives the DeliveryReq message for measuring the propagation delay time transmitted from the synchronization slaves 3a and 3b, the synchronization master 1 transmits a DeliveryResp message which is a response of the DeliveryReq message. The switching hub 2 that does not support IECEE1588 is a relay device that performs frame transfer according to the destination address of the received frame. The switching hub 2 can also be connected to three or more synchronous slaves. The synchronization slaves 3a and 3b measure the propagation delay time with the synchronization master 1 via the switching hub 2. In the following description, the Requester may be referred to as a first device, and the Responder may be referred to as a second device. Further, the first device which is a requester may be referred to as a time synchronization device.
　なお、通信システムの構成によっては、同期スレーブがＲｅｓｐｏｎｄｅｒになることもある。図２は、実施の形態１に係る通信システム４ａの構成例を示す図である。通信システム４ａは、同期マスタ１と、スイッチングハブ２と、同期スレーブ３ｃと、同期スレーブ３ｃに同期する同期スレーブ３ａ，３ｂと、を備える。図２に示す通信システム４ａでは、同期スレーブ３ａ，３ｂが同期スレーブ３ｃとの間の伝搬路の伝搬遅延時間を計測するＲｅｑｕｅｓｔｅｒとなり、同期スレーブ３ｃがＲｅｓｐｏｎｄｅｒとなる。図２に示す通信システム４ａにおいて、同期スレーブ３ｃは、ＩＥＥＥ１５８８の手順に従って、同期マスタ１との間の伝搬路の伝搬遅延時間を計測することができる。本実施の形態では、図１に示す通信システム４を例にして説明する。 Depending on the configuration of the communication system, the synchronous slave may be the Responder. FIG. 2 is a diagram showing a configuration example of the communication system 4a according to the first embodiment. The communication system 4a includes a synchronization master 1, a switching hub 2, a synchronization slave 3c, and synchronization slaves 3a and 3b that synchronize with the synchronization slave 3c. In the communication system 4a shown in FIG. 2, the synchronous slaves 3a and 3b serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronous slave 3c, and the synchronous slave 3c serves as a responder. In the communication system 4a shown in FIG. 2, the synchronization slave 3c can measure the propagation delay time of the propagation path to and from the synchronization master 1 according to the procedure of IECEE1588. In the present embodiment, the communication system 4 shown in FIG. 1 will be described as an example.
　同期スレーブ３ａ，３ｂの構成について説明する。図３は、実施の形態１に係る同期スレーブ３ａの構成例を示す図である。同期スレーブ３ａ，３ｂは同様の構成のため、同期スレーブ３ａを例にして説明する。同期スレーブ３ａは、フレーム受信部３１と、フレーム送信部３２と、時刻同期部３３と、受信監視部３４と、を備える。 The configuration of the synchronous slaves 3a and 3b will be described. FIG. 3 is a diagram showing a configuration example of the synchronous slave 3a according to the first embodiment. Since the synchronous slaves 3a and 3b have the same configuration, the synchronous slave 3a will be described as an example. The synchronization slave 3a includes a frame reception unit 31, a frame transmission unit 32, a time synchronization unit 33, and a reception monitoring unit 34.
　フレーム受信部３１は、フレーム解析部３１０を有する受信部である。フレーム解析部３１０は、スイッチングハブ２から受信したフレームを解析する。フレーム解析部３１０は、受信したフレームが時刻同期に関連するメッセージの場合、受信フレームに含まれていた受信データを時刻同期部３３に出力する。同期スレーブ３ａがＲｅｑｕｅｓｔｅｒの場合、フレーム解析部３１０は、時刻同期に関連するメッセージのうち同期スレーブ３ａ宛のＤｅｌａｙＲｅｓｐメッセージを受信すると、受信監視部３４にＤｅｌａｙＲｅｓｐメッセージを受信した旨を通知する。ＤｅｌａｙＲｅｓｐメッセージは、Ｒｅｓｐｏｎｄｅｒである同期マスタ１が、Ｒｅｑｕｅｓｔｅｒである同期スレーブ３ａから受信したＤｅｌａｙＲｅｑメッセージへの応答のメッセージである。以降の説明において、ＤｅｌａｙＲｅｓｐメッセージを応答メッセージと称することがある。また、ＤｅｌａｙＲｅｑメッセージは、Ｒｅｑｕｅｓｔｅｒである同期スレーブ３ａが、Ｒｅｓｐｏｎｄｅｒである同期マスタ１に伝搬遅延時間計測を要求するメッセージである。以降の説明において、ＤｅｌａｙＲｅｑメッセージを要求メッセージと称することがある。 The frame receiving unit 31 is a receiving unit having a frame analysis unit 310. The frame analysis unit 310 analyzes the frame received from the switching hub 2. When the received frame is a message related to time synchronization, the frame analysis unit 310 outputs the received data included in the received frame to the time synchronization unit 33. When the synchronization slave 3a is the Requester, the frame analysis unit 310 notifies the reception monitoring unit 34 that the DeliveryResp message has been received when it receives the DeliveryResp message addressed to the synchronization slave 3a among the messages related to time synchronization. The DelayResp message is a response message to the DelayReq message received by the sync master 1 which is the responder from the sync slave 3a which is the requester. In the following description, the DelayResp message may be referred to as a response message. The DelayReq message is a message in which the synchronous slave 3a, which is the requester, requests the synchronization master 1, which is the responder, to measure the propagation delay time. In the following description, the DelayReq message may be referred to as a request message.
　同期スレーブ３ａがＲｅｓｐｏｎｄｅｒの場合、フレーム解析部３１０は、時刻同期に関連するメッセージのうちＤｅｌａｙＲｅｑメッセージを受信すると、受信時点のタイムスタンプ値を保持する。フレーム解析部３１０は、保持したタイムスタンプ値、ＤｅｌａｙＲｅｑメッセージに含まれる情報であって送信元であるＲｅｑｕｅｓｔｅｒを示すＤｅｌａｙＲｅｑメッセージの送信元情報、およびＤｅｌａｙＲｅｑメッセージを受信した旨を、フレーム送信部３２に通知する。 When the synchronization slave 3a is a Responder, the frame analysis unit 310 holds the time stamp value at the time of reception when it receives the DelayReq message among the messages related to time synchronization. The frame analysis unit 310 notifies the frame transmission unit 32 of the retained time stamp value, the source information of the DelayReq message indicating the requester which is the information included in the DelayReq message and is the source, and the DelayReq message. To do.
　フレーム送信部３２は、送信周期タイマ３２０を有する送信部である。送信周期タイマ３２０は、フレーム送信部３２がＤｅｌａｙＲｅｑメッセージを送信する周期である送信周期Ｔでタイムアウトするタイマである。同期スレーブ３ａがＲｅｑｕｅｓｔｅｒの場合、フレーム送信部３２は、送信周期タイマ３２０が送信周期Ｔでタイムアウトすると、タイムアウト時、スイッチングハブ２にＤｅｌａｙＲｅｑメッセージを送信する。フレーム送信部３２は、ＤｅｌａｙＲｅｑメッセージを送信すると、ＤｅｌａｙＲｅｑメッセージを送信した旨を時刻同期部３３および受信監視部３４に通知する。また、フレーム送信部３２は、受信監視部３４からＤｅｌａｙＲｅｑメッセージの再送指示を受けると、ＤｅｌａｙＲｅｑメッセージを送信し、送信周期タイマ３２０を再起動する。 The frame transmission unit 32 is a transmission unit having a transmission cycle timer 320. The transmission cycle timer 320 is a timer that times out in the transmission cycle T, which is the cycle in which the frame transmission unit 32 transmits the DelayReq message. When the synchronous slave 3a is the Requester, the frame transmission unit 32 transmits a DelayReq message to the switching hub 2 at the time-out when the transmission cycle timer 320 times out in the transmission cycle T. When the frame transmission unit 32 transmits the DelayReq message, the frame transmission unit 32 notifies the time synchronization unit 33 and the reception monitoring unit 34 that the DelayReq message has been transmitted. Further, when the frame transmission unit 32 receives an instruction to retransmit the DeliveryReq message from the reception monitoring unit 34, the frame transmission unit 32 transmits the DeliveryReq message and restarts the transmission cycle timer 320.
　同期スレーブ３ａがＲｅｓｐｏｎｄｅｒの場合、フレーム送信部３２は、フレーム受信部３１から、タイムスタンプ値、ＤｅｌａｙＲｅｑメッセージの送信元情報、およびＤｅｌａｙＲｅｑメッセージを受信した旨が通知されると、タイムスタンプ値、およびＤｅｌａｙＲｅｑメッセージの送信元情報をＤｅｌａｙＲｅｓｐメッセージに格納して送信する。 When the synchronous slave 3a is a Reader, the frame transmitting unit 32 is notified by the frame receiving unit 31 that the time stamp value, the source information of the DelayReq message, and the DelayReq message have been received, and the time stamp value and the DelayReq are notified. The source information of the message is stored in the DelayResp message and transmitted.
　時刻同期部３３は、時刻カウンタ３３０を有する。時刻同期部３３は、フレーム受信部３１から受信データを取得した場合、取得した時点の時刻カウンタ３３０の時刻カウンタ値を記録する。時刻同期部３３は、フレーム送信部３２からＤｅｌａｙＲｅｑメッセージが送信された旨が通知された場合、通知された時点の時刻カウンタ３３０の時刻カウンタ値を記録する。時刻同期部３３は、記録した時刻カウンタ値とフレーム受信部３１から取得した受信データとを用いて同期マスタ１の時刻を算出し、時刻カウンタ３３０を同期マスタ１に同期させる。 The time synchronization unit 33 has a time counter 330. When the received data is acquired from the frame receiving unit 31, the time synchronization unit 33 records the time counter value of the time counter 330 at the time of acquisition. When the frame transmission unit 32 notifies that the DelayReq message has been transmitted, the time synchronization unit 33 records the time counter value of the time counter 330 at the time of notification. The time synchronization unit 33 calculates the time of the synchronization master 1 using the recorded time counter value and the reception data acquired from the frame reception unit 31, and synchronizes the time counter 330 with the synchronization master 1.
　例えば、フレーム送信部３２がＤｅｌａｙＲｅｑメッセージを送信した時刻をｔ１、同期マスタ１がＤｅｌａｙＲｅｑメッセージを受信した時刻をｔ２、同期マスタ１がＤｅｌａｙＲｅｓｐメッセージを送信した時刻をｔ３、フレーム受信部３１がＤｅｌａｙＲｅｓｐメッセージを受信した時刻をｔ４とする。同期スレーブ３ａは、同期マスタ１がｔ２およびｔ３の情報をＤｅｌａｙＲｅｓｐメッセージに含めることで、ｔ２およびｔ３の情報を取得することができる。時刻同期部３３は、（（ｔ４－ｔ３）＋（ｔ２－ｔ１））／２から片道の通信遅延時間を算出し、算出した片道の通信遅延時間を用いて同期マスタ１の時刻を算出し、時刻カウンタ３３０を同期マスタ１に同期させる。 For example, the time when the frame transmission unit 32 transmits the DelayReq message is t1, the time when the synchronization master 1 receives the DelayReq message is t2, the time when the synchronization master 1 transmits the DelayResp message is t3, and the frame reception unit 31 transmits the DelayResp message. Let t4 be the time of reception. The synchronization slave 3a can acquire the information of t2 and t3 by including the information of t2 and t3 in the DelayResp message by the synchronization master 1. The time synchronization unit 33 calculates the one-way communication delay time from ((t4-t3) + (t2-t1)) / 2, and calculates the time of the synchronization master 1 using the calculated one-way communication delay time. The time counter 330 is synchronized with the synchronization master 1.
　受信監視部３４は、受信監視タイマ３４０を有する。受信監視タイマ３４０は、ＤｅｌａｙＲｅｓｐメッセージの受信を監視するためのタイマである。受信監視部３４は、フレーム送信部３２がＤｅｌａｙＲｅｑメッセージを送信したときに受信監視タイマ３４０を起動する。受信監視部３４は、フレーム受信部３１がＤｅｌａｙＲｅｓｐメッセージを受信する前に受信監視タイマ３４０がタイムアウトした場合、フレーム送信部３２にＤｅｌａｙＲｅｑメッセージの再送を指示する。受信監視タイマ３４０のタイムアウト設定値をｔＯ、スイッチングハブ２に接続されるＲｅｑｕｅｓｔｅｒである同期スレーブ３ａ，３ｂの接続数をＮ、フレーム送信部３２がＤｅｌａｙＲｅｑメッセージを送信する送信周期をＴとすると、タイムアウト設定値ｔＯは、ｔＯ≦Ｔ／Ｎとなる値である。タイムアウト設定値ｔＯについては、例えば、通信システム４を管理するユーザが、あらかじめｔＯ≦Ｔ／Ｎとなる値を演算した結果を受信監視部３４に設定しておく。 The reception monitoring unit 34 has a reception monitoring timer 340. The reception monitoring timer 340 is a timer for monitoring the reception of the DelayResp message. The reception monitoring unit 34 activates the reception monitoring timer 340 when the frame transmission unit 32 transmits a DelayReq message. If the reception monitoring timer 340 times out before the frame receiving unit 31 receives the DelayResp message, the reception monitoring unit 34 instructs the frame transmitting unit 32 to retransmit the DelayReq message. When the timeout setting value of the reception monitoring timer 340 is tO, the number of connections of the synchronous slaves 3a and 3b which are the requesters connected to the switching hub 2 is N, and the transmission cycle in which the frame transmission unit 32 transmits the DelayReq message is T, the timeout is set. The set value tO is a value at which tO ≦ T / N. Regarding the timeout set value tO, for example, the user who manages the communication system 4 sets in the reception monitoring unit 34 the result of calculating a value such that tO ≦ T / N in advance.
　つづいて、同期スレーブ３ａ，３ｂの動作について説明する。図４は、実施の形態１に係る同期スレーブ３ａの受信監視部３４の監視動作を示すフローチャートである。同期スレーブ３ａ，３ｂは同様の動作を行うため、同期スレーブ３ａを例にして説明する。 Next, the operation of the synchronous slaves 3a and 3b will be described. FIG. 4 is a flowchart showing a monitoring operation of the reception monitoring unit 34 of the synchronous slave 3a according to the first embodiment. Since the synchronous slaves 3a and 3b perform the same operation, the synchronous slave 3a will be described as an example.
　受信監視部３４は、フレーム送信部３２からのＤｅｌａｙＲｅｑメッセージを送信した旨の通知の有無を確認する（ステップＳ１１）。受信監視部３４は、フレーム送信部３２からＤｅｌａｙＲｅｑメッセージを送信した旨の通知が無い場合（ステップＳ１１：Ｎｏ）、フレーム送信部３２からＤｅｌａｙＲｅｑメッセージを送信した旨の通知が有るまで待機する。受信監視部３４は、フレーム送信部３２からＤｅｌａｙＲｅｑメッセージを送信した旨の通知が有った場合（ステップＳ１１：Ｙｅｓ）、受信監視タイマ３４０を起動する（ステップＳ１２）。 The reception monitoring unit 34 confirms whether or not there is a notification that the DelayReq message has been transmitted from the frame transmission unit 32 (step S11). When there is no notification from the frame transmission unit 32 that the DelayReq message has been transmitted (step S11: No), the reception monitoring unit 34 waits until the frame transmission unit 32 notifies that the DelayReq message has been transmitted. The reception monitoring unit 34 activates the reception monitoring timer 340 (step S12) when the frame transmission unit 32 notifies that the DelayReq message has been transmitted (step S11: Yes).
　受信監視部３４は、受信監視タイマ３４０を起動すると、受信監視タイマ３４０のタイムアウトを確認する（ステップＳ１３）。受信監視部３４は、受信監視タイマ３４０がタイムアウトした場合（ステップＳ１３：Ｙｅｓ）、フレーム送信部３２にＤｅｌａｙＲｅｑメッセージの再送を指示する（ステップＳ１４）。 When the reception monitoring unit 34 activates the reception monitoring timer 340, the reception monitoring unit 34 confirms the timeout of the reception monitoring timer 340 (step S13). When the reception monitoring timer 340 times out (step S13: Yes), the reception monitoring unit 34 instructs the frame transmission unit 32 to retransmit the DelayReq message (step S14).
　受信監視部３４は、受信監視タイマ３４０がタイムアウトしていない場合（ステップＳ１３：Ｎｏ）、フレーム受信部３１からのＤｅｌａｙＲｅｓｐメッセージを受信した旨の通知の有無を確認する（ステップＳ１５）。受信監視部３４は、フレーム受信部３１からＤｅｌａｙＲｅｓｐメッセージを受信した旨の通知が有った場合（ステップＳ１５：Ｙｅｓ）、受信監視タイマ３４０を停止し、リセットする（ステップＳ１６）。受信監視部３４は、フレーム受信部３１からＤｅｌａｙＲｅｓｐメッセージを受信した旨の通知が無い場合（ステップＳ１５：Ｎｏ）、ステップＳ１３の動作に戻り、受信監視タイマ３４０のタイムアウトを確認する（ステップＳ１３）。 When the reception monitoring timer 340 has not timed out (step S13: No), the reception monitoring unit 34 confirms whether or not there is a notification that the DelayResp message has been received from the frame receiving unit 31 (step S15). When the reception monitoring unit 34 receives a notification from the frame receiving unit 31 that the DeliveryResp message has been received (step S15: Yes), the reception monitoring unit 34 stops and resets the reception monitoring timer 340 (step S16). When there is no notification from the frame receiving unit 31 that the DelayResp message has been received (step S15: No), the reception monitoring unit 34 returns to the operation of step S13 and confirms the timeout of the reception monitoring timer 340 (step S13).
　同期スレーブ３ａ，３ｂが伝搬遅延時間計測を行うときの、各装置のメッセージの送受信のタイミングについて説明する。図５は、実施の形態１に係る通信システム４において、同期スレーブ３ａ，３ｂが伝搬遅延時間計測を行うときの、各装置のメッセージの送受信のタイミングを示すシーケンス図である。ここでは、Ｒｅｓｐｏｎｄｅｒである同期マスタ１は、ＤｅｌａｙＲｅｑメッセージを受信したとき、タイムスタンプ値を１つのみ保持できるものとする。 The timing of sending and receiving messages of each device when the synchronous slaves 3a and 3b measure the propagation delay time will be described. FIG. 5 is a sequence diagram showing the timing of transmitting and receiving messages of each device when the synchronous slaves 3a and 3b measure the propagation delay time in the communication system 4 according to the first embodiment. Here, it is assumed that the synchronization master 1 which is a Responder can hold only one time stamp value when receiving the DelayReq message.
　Ｒｅｑｕｅｓｔｅｒである同期スレーブ３ａ，３ｂは、伝搬遅延時間計測を実施するため、ＤｅｌａｙＲｅｑメッセージを送信する。同期スレーブ３ａ，３ｂは、ＤｅｌａｙＲｅｑメッセージを送信すると、送信周期タイマ３２０および受信監視タイマ３４０を起動する（ステップＳ２１）。 The synchronous slaves 3a and 3b, which are requesters, transmit a DelayReq message in order to measure the propagation delay time. When the synchronous slaves 3a and 3b transmit the DelayReq message, the transmission cycle timer 320 and the reception monitoring timer 340 are activated (step S21).
　図５に示すシーケンス図の以降の説明において、同期スレーブ３ａが送信するＤｅｌａｙＲｅｑメッセージをＤｅｌａｙＲｅｑメッセージ３ａとし、同期スレーブ３ｂが送信するＤｅｌａｙＲｅｑメッセージをＤｅｌａｙＲｅｑメッセージ３ｂとし、同期マスタ１が同期スレーブ３ａに送信するＤｅｌａｙＲｅｓｐメッセージをＤｅｌａｙＲｅｓｐメッセージ３ａとし、同期マスタ１が同期スレーブ３ｂに送信するＤｅｌａｙＲｅｓｐメッセージをＤｅｌａｙＲｅｓｐメッセージ３ｂとする。 In the following description of the sequence diagram shown in FIG. 5, the DelayReq message transmitted by the synchronous slave 3a is referred to as the DelayReq message 3a, the DelayReq message transmitted by the synchronous slave 3b is referred to as the DelayReq message 3b, and the synchronous master 1 transmits to the synchronous slave 3a. The DelayResp message is referred to as a DelayResp message 3a, and the DelayResp message transmitted by the synchronization master 1 to the synchronization slave 3b is referred to as a DelayResp message 3b.
　Ｒｅｓｐｏｎｄｅｒである同期マスタ１は、同期スレーブ３ｂからのＤｅｌａｙＲｅｑメッセージ３ｂを先に受信し、受信時のタイムスタンプを保持する。同期マスタ１は、直後に受信した同期スレーブ３ａからのＤｅｌａｙＲｅｑメッセージ３ａを無視する。同期マスタ１は、同期スレーブ３ｂにＤｅｌａｙＲｅｓｐメッセージ３ｂを送信する（ステップＳ２２）。同期スレーブ３ｂは、ＤｅｌａｙＲｅｓｐメッセージ３ｂを受信すると、受信監視タイマ３４０を停止し、リセットする（ステップＳ２３）。 The synchronization master 1 which is a receiver receives the DelayReq message 3b from the synchronization slave 3b first, and retains the time stamp at the time of reception. The synchronization master 1 ignores the DelayReq message 3a from the synchronization slave 3a received immediately afterwards. The synchronization master 1 transmits a DelayResp message 3b to the synchronization slave 3b (step S22). When the synchronous slave 3b receives the DelayResp message 3b, the synchronous slave 3b stops and resets the reception monitoring timer 340 (step S23).
　同期スレーブ３ａは、受信監視タイマ３４０のタイムアウトにより、ＤｅｌａｙＲｅｑメッセージ３ａを再送し、送信周期タイマ３２０を再起動する（ステップＳ２４）。同期マスタ１は、同期スレーブ３ａからのＤｅｌａｙＲｅｑメッセージ３ａを受信し、受信時のタイムスタンプを保持する。同期マスタ１は、同期スレーブ３ａにＤｅｌａｙＲｅｓｐメッセージ３ａを送信する（ステップＳ２５）。同期スレーブ３ａは、ＤｅｌａｙＲｅｓｐメッセージ３ａを受信すると、受信監視タイマ３４０を停止し、リセットする（ステップＳ２６）。 The synchronous slave 3a retransmits the DelayReq message 3a due to the timeout of the reception monitoring timer 340, and restarts the transmission cycle timer 320 (step S24). The synchronization master 1 receives the DelayReq message 3a from the synchronization slave 3a and retains the time stamp at the time of reception. The synchronization master 1 transmits a DelayResp message 3a to the synchronization slave 3a (step S25). When the synchronous slave 3a receives the DelayResp message 3a, the synchronous slave 3a stops and resets the reception monitoring timer 340 (step S26).
　同期スレーブ３ｂは、送信周期タイマ３２０がタイムアウトすると、ＤｅｌａｙＲｅｑメッセージ３ｂを送信する。同期スレーブ３ｂは、ＤｅｌａｙＲｅｑメッセージ３ｂを送信すると、送信周期タイマ３２０および受信監視タイマ３４０を起動する（ステップＳ２７）。同期マスタ１は、同期スレーブ３ｂからのＤｅｌａｙＲｅｑメッセージ３ｂを受信し、受信時のタイムスタンプを保持する。同期マスタ１は、同期スレーブ３ｂにＤｅｌａｙＲｅｓｐメッセージ３ｂを送信する（ステップＳ２８）。同期スレーブ３ｂは、ＤｅｌａｙＲｅｓｐメッセージ３ｂを受信すると、受信監視タイマ３４０を停止し、リセットする（ステップＳ２９）。 The synchronous slave 3b transmits a DelayReq message 3b when the transmission cycle timer 320 times out. When the synchronous slave 3b transmits the DelayReq message 3b, the synchronous slave 3b activates the transmission cycle timer 320 and the reception monitoring timer 340 (step S27). The synchronization master 1 receives the DelayReq message 3b from the synchronization slave 3b and retains the time stamp at the time of reception. The synchronization master 1 transmits a DelayResp message 3b to the synchronization slave 3b (step S28). When the synchronous slave 3b receives the DelayResp message 3b, the synchronous slave 3b stops and resets the reception monitoring timer 340 (step S29).
　同期スレーブ３ａは、送信周期タイマ３２０がタイムアウトすると、ＤｅｌａｙＲｅｑメッセージ３ａを送信する。同期スレーブ３ａは、ＤｅｌａｙＲｅｑメッセージ３ａを送信すると、送信周期タイマ３２０および受信監視タイマ３４０を起動する（ステップＳ３０）。同期マスタ１は、同期スレーブ３ａからのＤｅｌａｙＲｅｑメッセージ３ａを受信し、受信時のタイムスタンプを保持する。同期マスタ１は、同期スレーブ３ａにＤｅｌａｙＲｅｓｐメッセージ３ａを送信する（ステップＳ３１）。同期スレーブ３ａは、ＤｅｌａｙＲｅｓｐメッセージ３ａを受信すると、受信監視タイマ３４０を停止し、リセットする（ステップＳ３２）。 The synchronous slave 3a transmits a DelayReq message 3a when the transmission cycle timer 320 times out. When the synchronous slave 3a transmits the DelayReq message 3a, the synchronous slave 3a activates the transmission cycle timer 320 and the reception monitoring timer 340 (step S30). The synchronization master 1 receives the DelayReq message 3a from the synchronization slave 3a and retains the time stamp at the time of reception. The synchronization master 1 transmits a DelayResp message 3a to the synchronization slave 3a (step S31). When the synchronous slave 3a receives the DelayResp message 3a, the synchronous slave 3a stops and resets the reception monitoring timer 340 (step S32).
　通信システム４では、以降、ステップＳ２７からステップＳ３２の動作が繰り返される。これにより、同期スレーブ３ａは、受信監視タイマ３４０のタイムアウトによるＤｅｌａｙＲｅｑメッセージの送信時、送信周期タイマ３２０のタイムアウト待ち状態にある同期スレーブ３ｂとは送信タイミングが重なることなく、ＤｅｌａｙＲｅｑメッセージを送信することができる。同期スレーブ３ａは、ＤｅｌａｙＲｅｑメッセージの送信タイミングが同期スレーブ３ｂと重なることがないため、伝搬遅延時間計測を完了することが可能となり、時刻同期を実施することができる。 In the communication system 4, the operations of steps S27 to S32 are repeated thereafter. As a result, when the synchronous slave 3a transmits the DelayReq message due to the timeout of the reception monitoring timer 340, the synchronous slave 3a can transmit the DelayReq message without overlapping the transmission timing with the synchronous slave 3b waiting for the timeout of the transmission cycle timer 320. it can. Since the synchronization slave 3a does not overlap with the synchronization slave 3b in the transmission timing of the DelayReq message, the propagation delay time measurement can be completed and the time synchronization can be performed.
　通信システム４では、スイッチングハブ２に接続されるＲｅｑｕｅｓｔｅｒである同期スレーブの接続数Ｎが３以上の場合においても、ｔＯ≦Ｔ／Ｎとすることで、伝搬遅延時間計測を完了した同期スレーブと未完了の同期スレーブとでＤｅｌａｙＲｅｑメッセージの送信タイミングが重なることがなくなる。この結果、通信システム４では、全ての同期スレーブが伝搬遅延時間計測を完了することが可能となり、時刻同期を実施することができる。 In the communication system 4, even when the number of connections N of the synchronous slaves, which are the requesters connected to the switching hub 2, is 3 or more, the propagation delay time measurement is not completed by setting tO ≦ T / N. The transmission timing of the DelayReq message does not overlap with the completed synchronous slave. As a result, in the communication system 4, all the synchronized slaves can complete the propagation delay time measurement, and the time synchronization can be performed.
　つづいて、同期スレーブ３ａのハードウェア構成について説明する。同期スレーブ３ａ，３ｂは同様の構成のため、同期スレーブ３ａを用いて説明する。図６は、実施の形態１に係る同期スレーブ３ａを実現するハードウェアの一例を示す図である。同期スレーブ３ａは、図６に示したプロセッサ１０１、記憶装置１０２、および通信インタフェース１０３により実現することができる。 Next, the hardware configuration of the synchronous slave 3a will be described. Since the synchronous slaves 3a and 3b have the same configuration, the synchronous slave 3a will be described. FIG. 6 is a diagram showing an example of hardware that realizes the synchronous slave 3a according to the first embodiment. The synchronous slave 3a can be realized by the processor 101, the storage device 102, and the communication interface 103 shown in FIG.
　プロセッサ１０１は、ＣＰＵ（Central　Processing　Unit、中央処理装置、処理装置、演算装置、マイクロプロセッサ、マイクロコンピュータ、ＤＳＰ（Digital　Signal　Processor）ともいう）、システムＬＳＩ（Large　Scale　Integration）などである。記憶装置１０２は、ＲＡＭ（Random　Access　Memory）、ＲＯＭ（Read　Only　Memory）、ＥＰＲＯＭ（Erasable　Programmable　Read　Only　Memory）、ＥＥＰＲＯＭ（登録商標）（Electrically　Erasable　Programmable　Read　Only　Memory）、ハードディスクドライブなどである。通信インタフェース１０３は、同期スレーブ３ａにおいて、フレーム受信部３１が通信フレームを受信し、フレーム送信部３２が通信フレームを送信するための処理回路であり、例えば、ネットワークインタフェースカードである。 The processor 101 is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor)), system LSI (Large Scale Integration), or the like. The storage device 102 includes a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), a hard disk drive, and the like. The communication interface 103 is a processing circuit for the frame receiving unit 31 to receive the communication frame and the frame transmitting unit 32 to transmit the communication frame in the synchronous slave 3a, and is, for example, a network interface card.
　同期スレーブ３ａにおいて、時刻同期部３３、受信監視部３４、フレーム受信部３１およびフレーム送信部３２において通信インタフェース１０３で実現される機能以外の部分は、これらの各部として動作するためのプログラムをプロセッサ１０１が実行することにより実現される。このようなプログラムは記憶装置１０２に予め格納されている。プロセッサ１０１は、上記プログラムを記憶装置１０２から読み出して実行することにより、時刻同期部３３、受信監視部３４、フレーム受信部３１およびフレーム送信部３２において通信インタフェース１０３で実現される機能以外の部分を実現する。 In the synchronization slave 3a, the parts other than the functions realized by the communication interface 103 in the time synchronization unit 33, the reception monitoring unit 34, the frame reception unit 31 and the frame transmission unit 32 are the processors 101 for operating as each of these parts. Is realized by executing. Such a program is stored in the storage device 102 in advance. By reading and executing the above program from the storage device 102, the processor 101 performs parts other than the functions realized by the communication interface 103 in the time synchronization unit 33, the reception monitoring unit 34, the frame reception unit 31 and the frame transmission unit 32. Realize.
　上記プログラムは、記憶装置１０２に予め格納された状態でユーザに提供される形態であってもよいし、コンピュータなどで読み取り可能な記録媒体、例えば、ＣＤ（Compact　Disc）－ＲＯＭ、ＤＶＤ（Digital　Versatile　Disc）－ＲＯＭなどに書き込まれた状態でユーザに供給され、ユーザが記憶装置１０２にインストールする形態であってもよい。 The above program may be provided to the user in a state of being stored in the storage device 102 in advance, or may be a recording medium readable by a computer or the like, for example, a CD (Compact Disc) -ROM, a DVD (Digital Versatile). Disc) -It may be supplied to the user in a state of being written in a ROM or the like, and may be installed by the user in the storage device 102.
　以上説明したように、本実施の形態によれば、ＩＥＥＥ１５８８非対応のスイッチングハブ２が接続された通信システム４において、時刻同期を行う同期スレーブ３ａ，３ｂは、ＤｅｌａｙＲｅｑメッセージを送信するときに受信監視タイマ３４０を起動する。受信監視タイマ３４０のタイムアウト設定値をｔＯ、スイッチングハブ２に接続される同期スレーブ３ａ，３ｂの接続数をＮ、同期スレーブ３ａ，３ｂのＤｅｌａｙＲｅｑメッセージの送信周期をＴとし、ｔＯ≦Ｔ／Ｎとする。同期スレーブ３ａ，３ｂは、タイムアウト設定値ｔＯ内に同期マスタ１からＤｅｌａｙＲｅｓｐメッセージを受信しない場合、ＤｅｌａｙＲｅｑメッセージを再送する。同期スレーブ３ａ，３ｂは、再送したＤｅｌａｙＲｅｑメッセージで伝搬遅延時間計測ができた場合、ＤｅｌａｙＲｅｑメッセージを再送した時刻から送信周期Ｔの間隔でＤｅｌａｙＲｅｑメッセージを送信することとした。これにより、同期スレーブ３ａ，３ｂは、複数のＲｅｑｕｅｓｔｅｒである同期スレーブ３ａ，３ｂがＩＥＥＥ１５８８非対応のスイッチングハブ２が接続された通信システム４においても、伝搬遅延時間の計測をすることができ、時刻同期が可能となる。 As described above, according to the present embodiment, in the communication system 4 to which the switching hub 2 not compatible with IEEE1588 is connected, the synchronization slaves 3a and 3b that perform time synchronization monitor reception when transmitting the DelayReq message. Start the timer 340. The timeout setting value of the reception monitoring timer 340 is tO, the number of connections of the synchronous slaves 3a and 3b connected to the switching hub 2 is N, the transmission cycle of the DelayReq message of the synchronous slaves 3a and 3b is T, and tO ≦ T / N. To do. If the synchronization slaves 3a and 3b do not receive the DelayResp message from the synchronization master 1 within the timeout set value tO, the synchronization slaves 3a and 3b retransmit the DelayReq message. When the propagation delay time can be measured by the transmitted DelayReq message, the synchronous slaves 3a and 3b will transmit the DelayReq message at intervals of the transmission cycle T from the time when the DelayReq message is retransmitted. As a result, the synchronous slaves 3a and 3b can measure the propagation delay time even in the communication system 4 in which the synchronous slaves 3a and 3b, which are a plurality of requesters, are connected to the switching hub 2 which does not support the IEEE1588. Synchronization is possible.
実施の形態２．
　実施の形態２では、Ｒｅｑｕｅｓｔｅｒである同期スレーブが、接続数Ｎをカウントし、タイムアウト設定値ｔＯを自動で算出する。実施の形態１と異なる部分について説明する。 Embodiment 2.
In the second embodiment, the synchronous slave, which is a requester, counts the number of connections N and automatically calculates the timeout set value tO. A part different from the first embodiment will be described.
　図７は、実施の形態２に係る通信システム４Ａの構成例を示す図である。通信システム４Ａは、同期マスタ１と、スイッチングハブ２と、同期マスタ１に同期する同期スレーブ３Ａａ，３Ａｂと、を備える。図７に示す通信システム４Ａでは、同期スレーブ３Ａａ，３Ａｂが同期マスタ１との間の伝搬路の伝搬遅延時間を計測するＲｅｑｕｅｓｔｅｒとなり、同期マスタ１がＲｅｓｐｏｎｄｅｒとなる。 FIG. 7 is a diagram showing a configuration example of the communication system 4A according to the second embodiment. The communication system 4A includes a synchronization master 1, a switching hub 2, and synchronization slaves 3Aa and 3Ab that synchronize with the synchronization master 1. In the communication system 4A shown in FIG. 7, the synchronous slaves 3Aa and 3Ab serve as a requester for measuring the propagation delay time of the propagation path to and from the synchronous master 1, and the synchronous master 1 serves as a responder.
　なお、通信システムの構成によっては、同期スレーブがＲｅｓｐｏｎｄｅｒになることもある。図８は、実施の形態２に係る通信システム４Ａａの構成例を示す図である。通信システム４Ａａは、同期マスタ１と、スイッチングハブ２と、同期スレーブ３Ａｃと、同期スレーブ３Ａｃに同期する同期スレーブ３Ａａ，３Ａｂと、を備える。図８に示す通信システム４Ａａでは、同期スレーブ３Ａａ，３Ａｂが同期スレーブ３Ａｃとの間の伝搬路の伝搬遅延時間を計測するＲｅｑｕｅｓｔｅｒとなり、同期スレーブ３ＡｃがＲｅｓｐｏｎｄｅｒとなる。図８に示す通信システム４Ａａにおいて、同期スレーブ３Ａｃは、ＩＥＥＥ１５８８の手順に従って、同期マスタ１との間の伝搬路の伝搬遅延時間を計測することができる。本実施の形態では、図７に示す通信システム４Ａを例にして説明する。 Depending on the configuration of the communication system, the synchronous slave may be the Responder. FIG. 8 is a diagram showing a configuration example of the communication system 4Aa according to the second embodiment. The communication system 4Aa includes a synchronization master 1, a switching hub 2, a synchronization slave 3Ac, and synchronization slaves 3Aa and 3Ab that synchronize with the synchronization slave 3Ac. In the communication system 4Aa shown in FIG. 8, the synchronous slaves 3Aa and 3Ab serve as a requester for measuring the propagation delay time of the propagation path between the synchronous slaves 3Aa and 3Ab, and the synchronous slave 3Ac serves as a responder. In the communication system 4Aa shown in FIG. 8, the synchronization slave 3Ac can measure the propagation delay time of the propagation path to and from the synchronization master 1 according to the procedure of IECEE1588. In the present embodiment, the communication system 4A shown in FIG. 7 will be described as an example.
　同期スレーブ３Ａａ，３Ａｂの構成について説明する。図９は、実施の形態２に係る同期スレーブ３Ａａの構成例を示す図である。同期スレーブ３Ａａ，３Ａｂは同様の構成のため、同期スレーブ３Ａａを例にして説明する。同期スレーブ３Ａａは、フレーム受信部３１Ａと、フレーム送信部３２と、時刻同期部３３と、受信監視部３４Ａと、を備える。 The configuration of the synchronous slaves 3Aa and 3Ab will be described. FIG. 9 is a diagram showing a configuration example of the synchronous slave 3Aa according to the second embodiment. Since the synchronous slaves 3Aa and 3Ab have the same configuration, the synchronous slave 3Aa will be described as an example. The synchronization slave 3Aa includes a frame reception unit 31A, a frame transmission unit 32, a time synchronization unit 33, and a reception monitoring unit 34A.
　フレーム受信部３１Ａは、フレーム解析部３１０Ａと、テーブル管理部３１１Ａと、カウンタ３１２Ａと、を有する受信部である。 The frame receiving unit 31A is a receiving unit having a frame analysis unit 310A, a table management unit 311A, and a counter 312A.
　フレーム解析部３１０Ａは、スイッチングハブ２から受信したフレームを解析する。フレーム解析部３１０Ａは、受信したフレームが時刻同期に関連するメッセージの場合、受信フレームに含まれていた受信データを時刻同期部３３に出力する。同期スレーブ３ＡａがＲｅｑｕｅｓｔｅｒの場合、フレーム解析部３１０Ａは、時刻同期に関連するメッセージのうち同期スレーブ３Ａａ宛のＤｅｌａｙＲｅｓｐメッセージを受信すると、受信監視部３４ＡにＤｅｌａｙＲｅｓｐメッセージを受信した旨を通知する。フレーム解析部３１０Ａは、時刻同期に関連するメッセージのうち他のＲｅｑｕｅｓｔｅｒである同期スレーブから送信されたＤｅｌａｙＲｅｑメッセージを受信すると、ＤｅｌａｙＲｅｑメッセージに含まれる情報であって送信元である同期スレーブを示すＲｅｑｕｅｓｔｅｒ識別情報をテーブル管理部３１１Ａに通知する。Ｒｅｑｕｅｓｔｅｒ識別情報は、例えば、ＭＡＣ（Media　Access　Control）アドレスなどである。 The frame analysis unit 310A analyzes the frame received from the switching hub 2. When the received frame is a message related to time synchronization, the frame analysis unit 310A outputs the received data included in the received frame to the time synchronization unit 33. When the synchronous slave 3Aa is the Requester, the frame analysis unit 310A notifies the reception monitoring unit 34A that the DelayResp message has been received when it receives the DelayResp message addressed to the synchronous slave 3Aa among the messages related to time synchronization. When the frame analysis unit 310A receives the DelayReq message transmitted from the synchronization slave which is another requester among the messages related to time synchronization, the requester identification which is the information included in the DelayReq message and indicates the synchronization slave which is the source. Notify the information to the table management unit 311A. The Requester identification information is, for example, a MAC (Media Access Control) address or the like.
　同期スレーブ３ＡａがＲｅｓｐｏｎｄｅｒの場合、フレーム解析部３１０Ａは、時刻同期に関連するメッセージのうちＤｅｌａｙＲｅｑメッセージを受信すると、受信時点のタイムスタンプ値を保持する。フレーム解析部３１０Ａは、保持したタイムスタンプ値、ＤｅｌａｙＲｅｑメッセージに含まれる情報であって送信元であるＲｅｑｕｅｓｔｅｒを示すＤｅｌａｙＲｅｑメッセージの送信元情報、およびＤｅｌａｙＲｅｑメッセージを受信した旨を、フレーム送信部３２に通知する。 When the synchronization slave 3Aa is a Reader, the frame analysis unit 310A holds the time stamp value at the time of reception when it receives the DelayReq message among the messages related to time synchronization. The frame analysis unit 310A notifies the frame transmission unit 32 of the retained time stamp value, the source information of the DelayReq message indicating the requester which is the information included in the DelayReq message and the source, and the fact that the DelayReq message has been received. To do.
　テーブル管理部３１１Ａは、フレーム解析部３１０Ａから通知されたＲｅｑｕｅｓｔｅｒ識別情報を、テーブル管理部３１１Ａが有するＲｅｑｕｅｓｔｅｒテーブルに登録する。テーブル管理部３１１Ａは、Ｒｅｑｕｅｓｔｅｒ識別情報がＲｅｑｕｅｓｔｅｒテーブルに新規に登録される場合、カウンタ３１２Ａを１カウントアップする。カウンタ３１２Ａのカウンタ値の初期値は１とする。テーブル管理部３１１Ａは、Ｒｅｑｕｅｓｔｅｒテーブルに登録されたＲｅｑｕｅｓｔｅｒ識別情報について、規定された時間内にフレーム解析部３１０Ａから同一のＲｅｑｕｅｓｔｅｒ識別情報が通知されなかった場合、Ｒｅｑｕｅｓｔｅｒテーブルから該当するＲｅｑｕｅｓｔｅｒ識別情報を削除し、カウンタ３１２Ａを１カウントダウンする。 The table management unit 311A registers the requester identification information notified from the frame analysis unit 310A in the requester table of the table management unit 311A. The table management unit 311A counts up the counter 312A by 1 when the requester identification information is newly registered in the requester table. The initial value of the counter value of the counter 312A is 1. When the same Requester identification information is not notified from the frame analysis unit 310A within the specified time for the Requester identification information registered in the Requester table, the table management unit 311A deletes the corresponding Requester identification information from the Requester table. Then, the counter 312A is counted down by one.
　フレーム解析部３１０Ａまたはテーブル管理部３１１Ａは、カウンタ３１２Ａのカウンタ値を受信監視部３４Ａに通知する。このように、同期スレーブ３Ａａにおいて、フレーム受信部３１Ａは、他のＲｅｑｕｅｓｔｅｒである同期スレーブが送信するＤｅｌａｙＲｅｑメッセージを受信した数によって、スイッチングハブ２に接続されるＲｅｑｕｅｓｔｅｒである同期スレーブの接続数Ｎをカウントする。 The frame analysis unit 310A or the table management unit 311A notifies the reception monitoring unit 34A of the counter value of the counter 312A. In this way, in the synchronous slave 3Aa, the frame receiving unit 31A determines the number of connections N of the synchronous slaves that are the requesters connected to the switching hub 2 depending on the number of received DelayReq messages transmitted by the synchronous slaves that are other requesters. Count.
　受信監視部３４Ａは、受信監視タイマ３４０Ａと、タイムアウト値設定部３４１Ａと、を有する。 The reception monitoring unit 34A has a reception monitoring timer 340A and a timeout value setting unit 341A.
　タイムアウト値設定部３４１Ａは、フレーム受信部３１Ａから通知されたカウンタ３１２Ａのカウンタ値を用いて、受信監視タイマ３４０Ａのタイムアウト設定値ｔＯを算出する。具体的には、タイムアウト値設定部３４１Ａは、カウンタ３１２Ａのカウンタ値を接続数Ｎとして、ｔＯ≦Ｔ／Ｎとなるように、受信監視タイマ３４０Ａのタイムアウト設定値ｔＯを算出する。タイムアウト値設定部３４１Ａは、算出した受信監視タイマ３４０Ａのタイムアウト設定値ｔＯを受信監視タイマ３４０Ａに通知する。 The timeout value setting unit 341A calculates the timeout setting value tO of the reception monitoring timer 340A by using the counter value of the counter 312A notified from the frame reception unit 31A. Specifically, the timeout value setting unit 341A calculates the timeout setting value tO of the reception monitoring timer 340A so that tO ≦ T / N, where the counter value of the counter 312A is the number of connections N. The timeout value setting unit 341A notifies the reception monitoring timer 340A of the calculated timeout setting value tO of the reception monitoring timer 340A.
　受信監視タイマ３４０Ａは、ＤｅｌａｙＲｅｓｐメッセージの受信を監視するためのタイマである。受信監視タイマ３４０Ａのタイムアウト設定値ｔＯは、タイムアウト値設定部３４１Ａから通知された値となる。 The reception monitoring timer 340A is a timer for monitoring the reception of the DelayResp message. The timeout setting value tO of the reception monitoring timer 340A is the value notified from the timeout value setting unit 341A.
　このように、受信監視部３４Ａは、フレーム受信部３１Ａでカウントされた接続数Ｎ、および送信周期Ｔを用いて、タイムアウト設定値ｔＯを算出する。 In this way, the reception monitoring unit 34A calculates the timeout set value tO using the number of connections N counted by the frame reception unit 31A and the transmission cycle T.
　つづいて、同期スレーブ３Ａａ，３Ａｂの動作について説明する。図１０は、実施の形態２に係る同期スレーブ３Ａａの受信監視部３４Ａがタイムアウト設定値ｔＯを算出する動作を示すフローチャートである。同期スレーブ３Ａａ，３Ａｂは同様の動作を行うため、同期スレーブ３Ａａを例にして説明する。 Next, the operation of the synchronous slaves 3Aa and 3Ab will be described. FIG. 10 is a flowchart showing an operation in which the reception monitoring unit 34A of the synchronous slave 3Aa according to the second embodiment calculates the timeout set value tO. Since the synchronous slaves 3Aa and 3Ab perform the same operation, the synchronous slave 3Aa will be described as an example.
　受信監視部３４Ａにおいて、タイムアウト値設定部３４１Ａは、フレーム受信部３１Ａからカウンタ３１２Ａのカウンタ値を取得する（ステップＳ４１）。タイムアウト値設定部３４１Ａは、カウンタ３１２Ａのカウンタ値を接続数Ｎとして、接続数Ｎ、およびフレーム送信部３２の送信周期タイマ３２０が送信周期Ｔを用いて、ｔＯ≦Ｔ／Ｎとなるタイムアウト設定値ｔＯを算出する（ステップＳ４２）。タイムアウト値設定部３４１Ａは、算出したタイムアウト設定値ｔＯを受信監視タイマ３４０Ａに通知する（ステップＳ４３）。タイムアウト設定値ｔＯを用いた受信監視部３４Ａの監視動作は、図４に示す実施の形態１の受信監視部３４の監視動作と同様のため、詳細説明については省略する。 In the reception monitoring unit 34A, the timeout value setting unit 341A acquires the counter value of the counter 312A from the frame reception unit 31A (step S41). The timeout value setting unit 341A uses the counter value of the counter 312A as the number of connections N, the number of connections N, and the transmission cycle timer 320 of the frame transmission unit 32 uses the transmission cycle T, so that the timeout setting value is to ≦ T / N. Calculate toO (step S42). The timeout value setting unit 341A notifies the reception monitoring timer 340A of the calculated timeout setting value tO (step S43). Since the monitoring operation of the reception monitoring unit 34A using the timeout set value tO is the same as the monitoring operation of the reception monitoring unit 34 of the first embodiment shown in FIG. 4, detailed description thereof will be omitted.
　同期スレーブ３Ａａについては、実施の形態１の同期スレーブ３ａと同様、図６に示すハードウェア構成により実現される。 The synchronous slave 3Aa is realized by the hardware configuration shown in FIG. 6, as in the synchronous slave 3a of the first embodiment.
　以上説明したように、本実施の形態によれば、同期スレーブ３Ａａ，３Ａｂは、受信した他の同期スレーブからのＤｅｌａｙＲｅｑメッセージの数からスイッチングハブ２に接続されるＲｅｑｕｅｓｔｅｒの接続数Ｎを求め、接続数Ｎを用いて受信監視タイマ３４０Ａのタイムアウト設定値ｔＯを算出することとした。これにより、同期スレーブ３Ａａ，３Ａｂは、受信監視タイマ３４０Ａのタイムアウト設定値ｔＯを自動で算出できる。この結果、ユーザが通信システム４Ａの構成の違いによりタイムアウト設定値を算出して変更することなく、容易に通信システム４Ａを運用することができる。 As described above, according to the present embodiment, the synchronous slaves 3Aa and 3Ab obtain the connection number N of the requesters connected to the switching hub 2 from the number of DelayReq messages received from the other synchronous slaves, and connect them. It was decided to calculate the timeout set value tO of the reception monitoring timer 340A using the number N. As a result, the synchronous slaves 3Aa and 3Ab can automatically calculate the timeout set value tO of the reception monitoring timer 340A. As a result, the user can easily operate the communication system 4A without calculating and changing the timeout setting value due to the difference in the configuration of the communication system 4A.
　以上の実施の形態に示した構成は、本発明の内容の一例を示すものであり、別の公知の技術と組み合わせることも可能であるし、本発明の要旨を逸脱しない範囲で、構成の一部を省略、変更することも可能である。 The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.
　１　同期マスタ、２　スイッチングハブ、３ａ，３ｂ，３ｃ，３Ａａ，３Ａｂ，３Ａｃ　同期スレーブ、４，４ａ，４Ａ，４Ａａ　通信システム、３１，３１Ａ　フレーム受信部、３２　フレーム送信部、３３　時刻同期部、３４，３４Ａ　受信監視部、３１０，３１０Ａ　フレーム解析部、３１１Ａ　テーブル管理部、３１２Ａ　カウンタ、３２０　送信周期タイマ、３３０　時刻カウンタ、３４０，３４０Ａ　受信監視タイマ、３４１Ａ　タイムアウト値設定部。 1 synchronization master, 2 switching hub, 3a, 3b, 3c, 3Aa, 3Ab, 3Ac synchronization slave, 4,4a, 4A, 4Aa communication system, 31, 31A frame receiver, 32 frame transmission, 33 time synchronization, 34 , 34A reception monitoring unit, 310,310A frame analysis unit, 311A table management unit, 312A counter, 320 transmission cycle timer, 330 time counter, 340,340A reception monitoring timer, 341A timeout value setting unit.

Claims (5)

  1. 　第１の装置が、複数の前記第１の装置を接続可能な中継装置を介して第２の装置との間で伝搬遅延時間計測を実施する前記第１の装置である時刻同期装置であって、
    　前記第２の装置に前記伝搬遅延時間計測の要求メッセージを送信する送信部と、
    　前記要求メッセージの応答である前記第２の装置からの応答メッセージを受信する受信部と、
    　受信監視タイマを有し、前記送信部が前記要求メッセージを送信したときに前記受信監視タイマを起動し、前記受信部が前記応答メッセージを受信する前に前記受信監視タイマがタイムアウトした場合、前記送信部に前記要求メッセージの再送を指示する受信監視部と、
    　を備え、
    　前記受信監視タイマのタイムアウト設定値をｔＯ、前記中継装置に接続される時刻同期装置の接続数をＮ、前記送信部の前記要求メッセージの送信周期をＴとし、ｔＯ≦Ｔ／Ｎであることを特徴とする時刻同期装置。     The first device is a time synchronization device which is the first device that measures propagation delay time with a second device via a relay device to which a plurality of the first devices can be connected. ,
    A transmission unit that transmits the request message for measuring the propagation delay time to the second device, and
    A receiving unit that receives a response message from the second device, which is a response of the request message, and a receiver.
    When the reception monitoring timer has a reception monitoring timer, the reception monitoring timer is activated when the transmission unit transmits the request message, and the reception monitoring timer times out before the reception unit receives the response message, the transmission is performed. A reception monitoring unit that instructs the unit to retransmit the request message,
    With
    The timeout setting value of the reception monitoring timer is tO, the number of connections of the time synchronization device connected to the relay device is N, the transmission cycle of the request message of the transmission unit is T, and tO ≦ T / N. A featured time synchronizer.
  2. 　前記送信部は、他の時刻同期装置が送信する要求メッセージを受信した数によって前記中継装置に接続される時刻同期装置の接続数をカウントし、
    　前記受信監視部は、前記受信部でカウントされた前記接続数、および前記送信周期を用いて、前記タイムアウト設定値を算出する、
    　ことを特徴とする請求項１に記載の時刻同期装置。     The transmission unit counts the number of connections of the time synchronization device connected to the relay device based on the number of request messages transmitted by the other time synchronization device.
    The reception monitoring unit calculates the timeout set value using the number of connections counted by the reception unit and the transmission cycle.
    The time synchronization device according to claim 1.
  3. 　請求項１または２に記載の時刻同期装置である第１の装置と、
    　複数の前記第１の装置を接続可能な中継装置と、
    　前記第１の装置から送信された伝搬遅延時間計測の要求メッセージを受信した場合、前記要求メッセージの応答である応答メッセージを送信する第２の装置と、
    　を備えることを特徴とする通信システム。     The first device, which is the time synchronization device according to claim 1 or 2,
    A relay device capable of connecting a plurality of the first devices,
    When the request message for measuring the propagation delay time transmitted from the first device is received, the second device that transmits the response message that is the response of the request message and the second device.
    A communication system characterized by comprising.
  4. 　第１の装置が、複数の前記第１の装置を接続可能な中継装置を介して第２の装置との間で伝搬遅延時間計測を実施する前記第１の装置である時刻同期装置の時刻同期方法であって、
    　送信部が、前記第２の装置に前記伝搬遅延時間計測の要求メッセージを送信する送信ステップと、
    　受信部が、前記要求メッセージの応答である前記第２の装置からの応答メッセージを受信する受信ステップと、
    　受信監視部が、受信監視タイマを有し、前記送信部が前記要求メッセージを送信したときに前記受信監視タイマを起動し、前記受信部が前記応答メッセージを受信する前に前記受信監視タイマがタイムアウトした場合、前記送信部に前記要求メッセージの再送を指示する監視ステップと、
    　を含み、
    　前記受信監視タイマのタイムアウト設定値をｔＯ、前記中継装置に接続される時刻同期装置の接続数をＮ、前記送信部の前記要求メッセージの送信周期をＴとし、ｔＯ≦Ｔ／Ｎであることを特徴とする時刻同期方法。     Time synchronization of the time synchronization device, which is the first device, in which the first device measures the propagation delay time with and from the second device via a relay device to which a plurality of the first devices can be connected. The way,
    A transmission step in which the transmission unit transmits the request message for measuring the propagation delay time to the second device, and
    A receiving step in which the receiving unit receives the response message from the second device, which is the response of the request message,
    The reception monitoring unit has a reception monitoring timer, and when the transmitting unit transmits the request message, the reception monitoring timer is activated, and the reception monitoring timer times out before the receiving unit receives the response message. If so, a monitoring step instructing the transmitter to retransmit the request message, and
    Including
    The timeout setting value of the reception monitoring timer is tO, the number of connections of the time synchronization device connected to the relay device is N, the transmission cycle of the request message of the transmission unit is T, and tO ≦ T / N. A featured time synchronization method.
  5. 　第１の装置が、複数の前記第１の装置を接続可能な中継装置を介して第２の装置との間で伝搬遅延時間計測を実施する前記第１の装置である時刻同期装置の時刻同期プログラムであって、
    　送信部が、前記第２の装置に前記伝搬遅延時間計測の要求メッセージを送信する送信ステップと、
    　受信部が、前記要求メッセージの応答である前記第２の装置からの応答メッセージを受信する受信ステップと、
    　受信監視部が、受信監視タイマを有し、前記送信部が前記要求メッセージを送信したときに前記受信監視タイマを起動し、前記受信部が前記応答メッセージを受信する前に前記受信監視タイマがタイムアウトした場合、前記送信部に前記要求メッセージの再送を指示する監視ステップと、
    　をコンピュータに実行させ、
    　前記受信監視タイマのタイムアウト設定値をｔＯ、前記中継装置に接続される時刻同期装置の接続数をＮ、前記送信部の前記要求メッセージの送信周期をＴとし、ｔＯ≦Ｔ／Ｎであることを特徴とする時刻同期プログラム。     Time synchronization of the time synchronization device, which is the first device, in which the first device measures the propagation delay time with and from the second device via a relay device to which a plurality of the first devices can be connected. It ’s a program
    A transmission step in which the transmission unit transmits the request message for measuring the propagation delay time to the second device, and
    A receiving step in which the receiving unit receives the response message from the second device, which is the response of the request message,
    The reception monitoring unit has a reception monitoring timer, and when the transmitting unit transmits the request message, the reception monitoring timer is activated, and the reception monitoring timer times out before the receiving unit receives the response message. If so, a monitoring step instructing the transmitter to retransmit the request message, and
    Let the computer run
    The timeout setting value of the reception monitoring timer is tO, the number of connections of the time synchronization device connected to the relay device is N, the transmission cycle of the request message of the transmission unit is T, and tO ≦ T / N. A featured time synchronization program.
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