JP2013029319A - Slave device, electronic apparatus system, master device, time synchronization method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent time synchronization precision of initial start time of a slave device from being reduced, to reduce a load to a network, and to shorten the time up to time synchronism, in time synchronization between a master device and a plurality of slave devices through a network.SOLUTION: When the value of a counter 11 exceeds a value indicating stabilization of an oscillator 15, a determination part 12 determines a busy state of a master device, but when the master device is not in the busy state, a transmission part 13 transmits a first message to the master device. A reception part 14 receives a second message and a follow-up message including the transmission time of the second message. A processing part 17 corrects an offset of a timer 16 on the basis of the difference between the transmission time and reception time of the second message. The transmission part 13 transmits a third message to the master device. The reception part 14 receives a fourth message including the reception time of the third message. The processing part 17 corrects propagation delay of the timer 16 on the basis of the difference between the reception time and transmission time of the third message.

Description

  The present invention relates to a slave device that performs time synchronization with a master device, an electronic device system that includes a master device that performs time synchronization and a plurality of slave devices, a master device that performs time synchronization with a slave device, and a master device and a slave device. The present invention relates to a time synchronization method and a program.

  As a time synchronization method using a network such as Ethernet (registered trademark), there is a method by time packet communication (PTP: Precision Time Protocol) from a master device to a slave device according to the IEEE 1588 standard. In the IEEE 1588 system, when configured by a master device and a slave device connected via a network, the time synchronization accuracy of the slave device is the network that performs the time packet communication with the stability of the oscillator mounted on the slave device and the master device. Depends on the load state.

  Here, when a slave device connected to the master device on the network newly performs time synchronization by time packet communication after the power is turned on, the time synchronization accuracy is the value of the oscillator in the slave device at the initial stage of power-on of the slave device. Depends on stability. When the stability of the oscillator in the slave device is improved as time elapses after the power is turned on, the time synchronization accuracy depends on the load state of the network that performs time packet communication with the master device. This is because the oscillator is not stable immediately after power-on of the slave device, so for example, an error due to the low stability of the oscillator of the slave device is added to the time received from the master device, and an accurate offset from the master device This is because the time difference cannot be obtained.

  This problem is avoided by the fact that the frequency of the oscillator mounted on the slave device stabilizes with the passage of time after the power is turned on and falls within the accuracy range that does not interfere with time synchronization. On the other hand, in the time packet communication between the master device and the slave device via the network, the network load increases as the number of slave devices connected to one master device increases. Further, the network load is further increased due to the influence of data packet communication other than time packet communication. The greater the network load, the greater the fluctuation. Depending on the magnitude of the fluctuation, the time accuracy may be low in one packet communication. For this reason, the time accuracy is usually increased by using a result of a plurality of time packet communications.

  Patent Document 1 discloses a technique that can correct the time with high responsiveness without unnecessarily increasing network traffic. In the client device of Patent Literature 1, the time correction request transmission interval is determined based on an error. The transmission interval is determined so as to be short when the error is large and long when the error is small. Therefore, time correction can be performed without unnecessarily increasing network traffic.

  Patent Document 2 proposes an electronic device system that accurately realizes time synchronization with a master device using a slave device. In the electronic device system of Patent Document 2, the time correction of the clock unit of the slave device is performed without using the calculation result of the offset (Offset) including the error as in the conventional case, so that the slave device is connected to the time of the master device. Synchronize with high accuracy.

  Patent Document 3 presents an electronic device system that realizes complete time synchronization with a master device in a slave device. In this electronic device system, time information is sent as a counter value from the master device to the slave device, so that the master device converts the counter value into a value in units of nanoseconds (ns), for example, and the slave device uses the nanosecond ( ns) The unit value is not converted into a counter value. Therefore, the time information supplied from the master device to the slave device is accurate time information that does not include a calculation error during conversion. Thereby, the slave device can realize time synchronization with the master device with higher accuracy.

JP 2007-214670 A JP 2010-190635 A JP 2010-197320 A

  When a slave device is newly connected in an operating environment of a master device with a network configuration using IEEE 1588 and a plurality of slave devices, when the slave device is powered on, the frequency of the oscillator mounted on the slave device is not stable In this state, the time packet communication with the master device is performed under an already operated network load environment, and therefore there is a possibility that the synchronization pull-in time until a predetermined time synchronization accuracy is satisfied is prolonged.

  The techniques described in Patent Documents 1 to 3 prevent a decrease in time synchronization accuracy at the time of initial startup of a slave device in time synchronization between a master device and a plurality of slave devices with a network configuration using IEEE 1588, and reduce the load on the network. It does not reduce the time to time synchronization.

  The present invention has been made in view of the circumstances as described above. In the time synchronization through the network between the master device and the plurality of slave devices, the time synchronization accuracy at the time of initial activation of the slave device is prevented, and the network is provided. An object of the present invention is to provide a slave device, an electronic device system, a master device, a time synchronization method, and a program that can reduce the load on the device and reduce the time until time synchronization.

A slave device according to the first aspect of the present invention provides:
A slave device that performs time synchronization with a master device via a network,
A timer for generating time information;
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals;
A determination means for determining whether or not the master device is busy performing time synchronization with other slave devices when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. One receiving means;
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. When,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. A transmission means;
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means,
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
It is characterized by providing.

An electronic device system according to a second aspect of the present invention is:
An electronic device system including a master device that performs time synchronization via a network and two or more slave devices,
Each of the slave devices is
A timer that generates time information,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
Including
The master device is
Third receiving means for receiving the first message from the slave device;
When the third receiving unit receives the first message from the slave device, the second message and the follow-up message are transmitted to the target slave device that is the slave device of the other party that received the first message. Third transmitting means for
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
Fourth receiving means for receiving the third message from the target slave device; and
Fifth transmission means for transmitting the fourth message to the target slave device when the fourth reception means receives the third message from the target slave device;
It is characterized by including.

The master device according to the third aspect of the present invention is:
A master device that performs time synchronization with two or more slave devices via a network,
Third receiving means for receiving a first message for requesting start of time synchronization from the slave device;
When the third receiving unit receives the first message from the slave device, the third receiving unit includes a second message for obtaining an offset time difference between the master device and the slave device, and a time when the second message is transmitted. A third transmission means for transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
A fourth receiving means for receiving a third message for obtaining a propagation delay time between the master device and the slave device from the target slave device;
When the fourth receiving unit receives the third message from the target slave device, a fifth transmitting unit that transmits a fourth message including the time when the third message is received to the target slave device;
It is characterized by providing.

The time synchronization method according to the fourth aspect of the present invention is:
In an electronic device system including a master device that performs time synchronization via a network and two or more slave devices, the oscillator includes a clock that generates a clock for generating time information, and a counter that counts up at a predetermined interval A determination step of determining whether or not the master device is busy performing time synchronization with another slave device when the value of the counter executed by the slave device exceeds a predetermined value;
A first transmission step of transmitting a first message requesting the master device to start time synchronization when it is determined that the busy state is not determined in the determination step;
A third receiving step for receiving the first message from the slave device, which is executed by the master device;
When the first message is received from the slave device in the third receiving step, a second message for obtaining an offset time difference between the master device and the slave device and a time at which the second message is transmitted are included. A third transmission step of transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission step of transmitting a fifth message indicating the busy state to the slave device other than the target slave device when the second message is transmitted to the target slave device in the third transmission step;
A first receiving step of receiving the second message and the follow-up message from the master device, executed by the target slave device;
Offset calculating step for calculating the offset time difference based on the time when the second message is received in the first receiving step and the time when the second message included in the follow-up message is transmitted from the master device. When,
A second message for transmitting a third message for determining a propagation delay time between the master device and the slave device after receiving the follow-up message from the master device in the first receiving step; Sending step;
A fourth reception step of receiving the third message from the target slave device, executed by the master device;
When receiving the third message from the target slave device in the fourth reception step, a fifth transmission step of transmitting the fourth message including the time when the third message is received to the target slave device;
A second receiving step for receiving the fourth message from the master device, executed by the target slave device;
A delay time calculating step of calculating the propagation delay time based on a time when the third message is transmitted and a time when the master device receives the third message included in the fourth message;
A correction step of correcting the time of the timer based on the offset time difference and the propagation delay time;
It is characterized by providing.

A program according to a fifth aspect of the present invention provides a computer,
A timer that generates time information,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
It is made to function as.

  According to the present invention, in time synchronization via a network between a master device and a plurality of slave devices, a decrease in time synchronization accuracy at the time of initial startup of the slave device is prevented, a load on the network is reduced, and time synchronization is also achieved. Can be shortened.

It is a block diagram which shows the structural example of the electronic device system which concerns on embodiment of this invention. It is a figure explaining the time synchronization using PTP. It is a block diagram which shows an example of a structure of the slave apparatus which concerns on embodiment. It is a figure explaining an example of the time synchronization in the electronic device system which concerns on embodiment. It is a flowchart which shows an example of the operation | movement of the time synchronization of the slave apparatus which concerns on embodiment. It is a flowchart which shows an example of the operation | movement of the determination process of the slave apparatus which concerns on embodiment. It is a flowchart which shows an example of the operation | movement of the time synchronization of the slave apparatus which concerns on other embodiment. It is a flowchart which shows an example of the operation | movement of the time synchronization of the slave apparatus which concerns on other embodiment. It is a figure explaining an example of the time synchronization in the electronic device system which concerns on other embodiment. It is a block diagram which shows the hardware structural example of the slave apparatus which concerns on embodiment.

  In this embodiment, the first message is Announce Message 1, the second message is Announce Message 2, the follow-up message is Follow Up Message, the third message is Delay Request Message, the fourth message is Delay Response Message, and the fifth message is Announce Message 3.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

  FIG. 1 is a block diagram illustrating a configuration example of an electronic device system according to an embodiment of the present invention. The electronic device system 100 includes a master device M1 on the network and X slave devices S1 to SX. The master device M1 is connected to the slave devices S1 to SX via paths 21 to X, respectively, and performs time synchronization with respect to the respective slave devices S1 to SX. In this embodiment, IEEE 1588 is adopted as time synchronization, and time synchronization is performed by PTP. PTP synchronizes with the most accurate timer among the timers of all devices included in the system. That is, the device having the most accurate timer is the master device, and the other devices are slave devices. For this reason, the master device may be changed.

  FIG. 2 is a diagram for explaining time synchronization using PTP. An example of a general operation flow of time synchronization by PTP defined in the IEEE 1588 standard is shown. Here, it is assumed that the time of the master device when the master device sends a Sync Message is 0:00. First, the master device transmits a Sync Message for obtaining an offset time difference between the master device and the slave device to the slave device at time 0:00. Next, a Follow Up Message is transmitted from the master device to the slave device indicating that the Sync Message has been transmitted at time 0:00.

  The slave device receives a Sync Message at time 00:06 and receives a Follow UP Message at time 00:08. The slave device, based on the time 00:06 at which the Sync Message is received and the time 00:00 at which the Sync Message is transmitted from the master device included in the Follow UP Message, the offset time difference {00: 06-00: 00 = 00:06} is calculated, and offset correction 00:06 is subtracted from time 00:08 to perform offset correction at time 00:02.

  Next, in order to obtain the propagation delay time between the master device and the slave device, a Delay Request Message for obtaining the propagation delay time between the master device and the slave device at time 00:06 after offset correction from the slave device. Is sent to the master device. The master device sends a Delay Response Message that tells that the Delay Request Message has been received at time 00:12 to the slave device at time 00:13.

  The slave device receives the Delay Response Message at time 00:13 after the offset correction. Based on the time 00:06 after offset correction at which the Delay Request Message was transmitted and the time 00:12 at which the master device included in the Delay Response Message received the Delay Request Message, the slave device The propagation delay time {(00: 12-00: 06) / 2 = 00: 03} is calculated, and the propagation delay time 00:03 is added to the time 00:15 after offset correction to obtain the time 00:18. Propagation delay correction is performed. Thus, time synchronization between the master device and the slave device is performed.

  FIG. 3 is a block diagram illustrating an example of a configuration of the slave device according to the embodiment. The slave device S1 includes a counter 11, a determination unit 12, a transmission unit 13, a reception unit 14, an oscillator 15, a timer 16, and a processing unit 17. The slave devices S2 to SX have the same configuration.

  When the slave device S1 is activated, the counter 11 counts up at a predetermined interval (for example, every second). The counter 11 sends the counter value to the determination unit 12.

  When the counter value received from the counter 11 exceeds a predetermined value, the determination unit 12 performs a determination process for determining whether the master device M1 is in a busy state in which time synchronization is performed with another slave device. Do. The predetermined value is, for example, a value indicating a time until the oscillator 15 that supplies a clock to the timer 16 is stabilized, or a value indicating a time obtained by subtracting the shortest time for executing the determination process from the time when the oscillator 15 is stabilized. And it is preset.

  The transmission unit 13 transmits various messages to the master device M1. When the determination unit 12 determines that the determination unit 12 is not busy, the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master device M1. When the determination unit 12 determines that the determination unit 12 is busy, the transmission unit 13 does not transmit the Announce Message 1 to the master device M1.

  The receiving unit 14 receives various messages from the master device M1. The receiving unit 14 receives an Announce Message 2 for obtaining an offset time difference between the master device M1 and the slave device S1 from the master device M1, and includes a Follow UP including the time when the Announce Message 2 is transmitted from the master device M1. Receive a Message. The receiving unit 14 sends the Announce Message 2 and Follow UP Message received from the master device M1 to the processing unit 17.

  When the receiving unit 14 receives the Follow UP Message from the master device M1, the transmitting unit 13 sends a Delay Request Message for obtaining a propagation delay time between the master device M1 and the slave device S1 to the master device M1. Send to.

  The receiving unit 14 receives a Delay Response Message including the time when the master device M1 receives the Delay Request Message. The receiving unit 14 sends the Delay Response Message received from the master device M1 to the processing unit 17. In addition, when the receiving unit 14 receives the Announce Message 3 indicating that the master device M1 is busy, the receiving unit 14 sends the Announce Message 3 to the determination unit 12.

  Since the transmission unit 13 transmits each message for time synchronization after the determination unit 12 determines that it is not busy, there is no need to consider a collision, and the transmission interval is made shorter than normal time packet communication. Can be sent.

  The oscillator 15 generates a clock for generating time information and supplies it to the timer 16.

  The timer 16 measures time based on the clock supplied from the oscillator 15 and generates time information. Note that the timer 16 may include a counter 11, and the counter 11 may count up according to a clock generated by the oscillator 15.

  The processing unit 17 performs an offset based on the difference between the time when the Announce Message 2 included in the Follow UP Message received from the receiving unit 14 is transmitted from the master device M1 and the time when the receiving unit 14 receives the Announce Message 2. The time difference is calculated and the offset of the time of the timer 16 is corrected. Further, the processing unit 17 is based on the difference between the time when the master device M1 included in the Delay Response Message received from the receiving unit 14 receives the Delay Request Message and the time when the transmitting unit 13 transmits the Delay Request Message. The propagation delay time is calculated and the propagation time of the timer 16 is corrected. In this way, the processing unit 17 synchronizes the time of the timer 16 with the time of the master device M1.

  FIG. 4 is a diagram for explaining time synchronization in the electronic device system according to the embodiment. In the example of FIG. 4, for convenience, the electronic device system 100 includes a master device 1, a slave device S <b> 1, and a slave device S <b> 2, and shows a case where time synchronization of the slave device S <b> 1 is executed.

  When the slave device S1 is activated, the counter 11 starts counting up. When a predetermined time (10 seconds) elapses without the reception unit 14 receiving the Announce Message 3 after the counter value of the counter 11 becomes equal to or greater than N, the determination unit 12 determines that the master device M1 It is determined that the synchronization is not busy. The counter value N is a value indicating a time until the oscillator 15 that supplies a clock to the timer 16 is stabilized, or a value indicating a time obtained by subtracting the shortest time for executing the determination process from the time when the oscillator 15 is stabilized.

  At time 00:15 when the determination unit 12 determines that the state is not busy, the transmission unit 13 transmits an Announce Message 1 requesting the start of time synchronization to the master device M1. When master device M1 receives Announce Message 1 at time 00:03, master device M1 provides Announce Message 2 for obtaining an offset time difference between master device M1 and slave device S1 to slave device S1 at time 00:04. Send. At the same time, an Announce Message 3 indicating that the master device M1 is busy is transmitted to the slave device S2. Then, a Follow UP Message including the time 00:04 at which the Announce Message 2 is transmitted is transmitted to the slave device S1 at the time 00:05.

  The receiving unit 14 of the slave device S1 receives the Announce Message 2 at time 00:22 and receives the Follow UP Message at time 00:23. Based on the time 00:22 when the receiving unit 14 receives the Announce Message 2 and the time 00:04 when the Announce Message 2 is transmitted from the master device included in the Follow UP Message, the processing unit 17 Offset time difference {00: 22−00: 04 = 00: 18} is calculated, and offset correction is performed by subtracting offset time difference 00:18 from time 00:23 to time 00:05.

  Next, the transmission unit 13 of the slave device S1 transmits a Delay Request Message for obtaining a propagation delay time between the master device and the slave device to the master device M1 at time 00:06 after the offset correction. The master device transmits a Delay Response Message including time 00:12 at which the Delay Request Message is received to the slave device S1 at time 00:13.

  The receiving unit 14 of the slave device S1 receives the Delay Response Message at time 00:13 after the offset correction. Based on the time 00:06 after the offset correction when the transmission unit 13 transmitted the Delay Request Message and the time 00:12 when the master device M1 included in the Delay Response Message received the Delay Request Message, The propagation delay time {(00: 12-00: 06) / 2 = 00: 03} between the master device M1 and the slave device S1 is calculated, and the propagation delay time 00:03 is added to the time 00:15 after offset correction. Thus, propagation delay correction at time 00:18 is performed. Thus, time synchronization between the master device and the slave device is performed.

  On the other hand, the slave device S2 receives the Announce Message 3 from the master device M1 at time 00:02 before a predetermined time (10 seconds) elapses after the counter value of the counter 11 becomes N or more. Thereby, the determination part 12 determines with it being a busy state. Thereafter, since the Announce Message 3 is not received by the time 00:12 when the predetermined time (10 seconds) elapses, the determination unit 12 determines that the busy state has been released. Since the determination unit 12 determines that it is not busy, the transmission unit 13 transmits an Announce Message 1 requesting the start of time synchronization to the master device M1 at time 00:13.

  FIG. 5 is a flowchart illustrating an example of the time synchronization operation of the slave device according to the embodiment. Here, an example of the operation of time synchronization of the slave device S1 will be described. The slave devices S2 to SX perform the same time synchronization operation. At the same time as the power supply of the slave device S1 is activated, the counter 11 in the slave device S1 is activated (step S11), and count-up is started. If the counter value is not greater than or equal to N (step S12; NO), it is assumed that the stability of the oscillator 15 is poor and cannot be used for time synchronization, and step S12 is repeated without starting time synchronization. The counter value N is a value indicating a time until the oscillator 15 that supplies a clock to the timer 16 is stabilized, or a value indicating a time obtained by subtracting the shortest time for executing the determination process from the time when the oscillator 15 is stabilized.

  When the counter value is greater than or equal to N (step S12; YES), it is assumed that the stability of the oscillator 15 has reached the stability that can be used for time synchronization, and the determination unit 12 determines that the master device M1 is another slave device. It is determined whether or not the time is synchronized with the time (step S13).

  When the determination part 12 determines with it being a busy state (step S13; YES), step S13 is repeated until the busy state of the master apparatus M1 is cancelled | released. When the determination unit 12 determines that it is not busy (step S13; NO), the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master device M1 (step S14).

  When master device M1 receives Announce Message 1 from slave device S1, master device M1 transmits Announce Message 2 for obtaining an offset time difference between master device M1 and slave device S1 to slave device S1. At the same time, an Announce Message 3 indicating that the master device M1 is in a busy state is transmitted to the other slave devices. Alternatively, the master device M1 broadcasts an Announce Message 2 destined for the stave device S1 in order to notify other slave devices that time synchronization with the stave device S1 has started and is in a busy state. Also good. Then, the master device M1 transmits a Follow UP Message including the time when the Announce Message 2 is transmitted to the slave device S1.

  When the master device M1 receives the Announce Message 1 from a plurality of slave devices at the same time, the master device M1 randomly selects any one of these slave devices and transmits the Announce Message 2 to the selected slave device. Good. In this case, master device M1 transmits Announce Message 3 to the slave device that has not been selected. When the slave device that has not been selected receives the Announce Message 3, it determines that the master device M1 is busy, and then transmits the Announce Message 1 again when it is determined that the master device M1 is no longer busy.

  When the receiving unit 14 of the slave device S1 receives the Announce Message 2 from the master device M1 (Step S15) and receives a Follow UP Message including the time when the Announce Message 2 is transmitted from the master device M1 (Step S16), the processing unit 17 calculates an offset time difference based on the time when the Announce Message 2 is transmitted from the master device M1 included in the Follow UP Message and the time when the receiving unit 14 receives the Announce Message 2 (Step S17). Offset correction is performed (step S18).

  Next, the transmission unit 13 transmits a Delay Request Message for obtaining a propagation delay time between the master device M1 and the slave device S1 to the master device M1 at a transmission interval shorter than normal time packet communication (step S19). ). Here, the transmission interval is the time from when the receiving unit 14 receives the Follow UP Message to when the transmitting unit 13 transmits the Delay Request Message. Since a Message is not transmitted from another slave device to the master device M1, it is possible to transmit a Delay Request Message having a transmission interval shorter than that of normal time packet communication to the master device M1. As a result, it is possible to shorten the period until the time synchronization is completed.

  When receiving the Delay Request Message from the slave device S1, the master device M1 transmits a Delay Response Message including the time when the Delay Request Message is received to the slave device S1.

  When the reception unit 14 of the slave device S1 receives the Delay Response Message from the master device M1 (Step S20), the processing unit 17 transmits the time when the master device M1 included in the Delay Response Message receives the Delay Request Message, and the transmission unit 13 Calculates the propagation delay time based on the time when the Delay Request Message is transmitted (step S21), corrects the propagation delay of the timer 16 (step S22), and ends the process.

  FIG. 6 is a flowchart illustrating an example of operation of determination processing of the slave device according to the embodiment. Here, an example of the operation of the determination process performed by the slave device S1 in step S13 of FIG. 6 will be described. The slave devices S2 to SX perform the same determination processing operation. When the receiving unit 14 of the slave device S1 receives the Announce Message 3 from the master device M1 (step S31; YES), the determining unit 12 determines that the busy state is set (step S32) and executes step S33. When the receiving unit 14 does not receive the Announce Message 3 from the master device M1 (step S31; NO), it is determined whether or not a predetermined time has passed (step S33).

  The predetermined time here is a time longer than the maximum value of the interval at which the Announce Message 3 is transmitted from the master device M1. When it is determined that steps S18 to S20 are executed only once as in the flow of FIG. 5, the time is longer than the maximum time from when the Announce Message 3 is transmitted until the time synchronization ends. Set to. That is, the predetermined time is a time that can be assumed that the busy state of the master device M1 is released.

  If the required time has not elapsed (step S33; NO), the process returns to step S31, and steps S31 to S33 are repeated. If the required time has elapsed (step S33; YES), it is determined that the state is not busy (step S34), and the process ends.

  As described above, according to the electronic device system 100 of the present embodiment, the time packet communication with the master device is not performed for a predetermined time until the oscillator is stabilized after the slave device is powered on. Thus, it is possible to prevent deterioration in time synchronization accuracy at the time of initial startup, and to reduce the load on the network. Furthermore, since time synchronization is started after confirming that the master device is not busy, there is no need to consider collisions, and messages can be transmitted with a shorter transmission interval than normal time packet communication. The time until time synchronization can be shortened.

  In the above-described embodiment, the slave device performs time synchronization after the oscillator 15 is stabilized. However, the present invention is not limited to this, and when the propagation delay time is repeatedly calculated before the oscillator 15 is stabilized and is performed a predetermined number of times, the propagation delay time when the oscillator 15 is stabilized is predicted from the result. May be. Further, the calculation of the propagation delay time is repeatedly performed before the oscillator 15 is stabilized, and the calculation of the propagation delay time is repeated when the difference between the previous propagation delay time and the current propagation delay time is equal to or less than the threshold value. You may end.

  FIG. 7 is a flowchart illustrating an example of a time synchronization operation of a slave device according to another embodiment. In the embodiment of FIG. 7, the propagation delay time is repeatedly calculated before the oscillator 15 is stabilized, and when a predetermined number of times is performed, the propagation delay time when the oscillator 15 is stabilized is predicted from the result. Here, an example of the operation of time synchronization of the slave device S1 will be described. The slave devices S2 to SX perform the same time synchronization operation. At the same time as the power supply of the slave device S1 is activated, the counter 11 in the slave device S1 is activated (step S41), and count-up is started. If the counter value is not greater than or equal to N1 (step S42; NO), step S42 is repeated. The counter value N1 is a value indicating a time shorter than the time when the oscillator 15 is stabilized or a value indicating a time shorter than the time obtained by subtracting the shortest time for executing the determination process from the time when the oscillator 15 is stabilized.

  When the counter value is equal to or greater than N1 (step S42; YES), the determination unit 12 determines whether the master device M1 is in a busy state in which time synchronization is performed with another slave device (step S42). S43). When the determination part 12 determines with it being a busy state (step S43; YES), step S43 is repeated until the busy state of the master apparatus M1 is cancelled | released. When the master apparatus M1 is not busy (step S43; NO), the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master apparatus M1 (step S44).

  When master device M1 receives Announce Message 1 from slave device S1, master device M1 transmits Announce Message 2 for obtaining an offset time difference between master device M1 and slave device S1 to slave device S1. At the same time, an Announce Message 3 indicating that the master device M1 is in a busy state is transmitted to the other slave devices. Alternatively, the master device M1 broadcasts an Announce Message 2 destined for the stave device S1 in order to notify other slave devices that time synchronization with the stave device S1 has started and is in a busy state. Also good. Then, the master device M1 transmits a Follow UP Message including the time when the Announce Message 2 is transmitted to the slave device S1.

  When the receiving unit 14 of the slave device S1 receives the Announce Message 2 from the master device M1 (Step S45) and receives a Follow UP Message including the time when the Announce Message 2 is transmitted from the master device M1 (Step S46), the processing unit 17 calculates an offset time difference based on the time when the Announce Message 2 is transmitted from the master device M1 included in the Follow UP Message and the time when the receiving unit 14 receives the Announce Message 2 (Step S47). Offset correction is performed (step S48).

  Next, the transmission unit 13 transmits a Delay Request Message for obtaining a propagation delay time between the master device M1 and the slave device S1 to the master device M1 at a transmission interval shorter than normal time packet communication (step S49). ). Here, the transmission interval is the time from when the receiving unit 14 receives the Follow UP Message to when the transmitting unit 13 transmits the Delay Request Message.

  When receiving the Delay Request Message from the slave device S1, the master device M1 transmits a Delay Response Message including the time when the Delay Request Message is received to the slave device S1. At the same time, Announce Message 3 indicating that the master device M1 is busy is transmitted to the other slave devices. Alternatively, the master device M1 may broadcast a Delay Response Message destined for the stave device S1 in order to notify other slave devices that it is busy for time synchronization with the stave device S1.

  When the receiving unit 14 of the slave device S1 receives the Delay Response Message from the master device M1 (Step S50), the processing unit 17 transmits the time at which the transmitting unit 13 transmits the Delay Request Message and the master device M1 included in the Delay Response Message. The propagation delay time is calculated based on the time when the delay request message is received (step S51). When step S49 to step S51 are not repeated a predetermined number of times (step S52; NO), the process returns to step S49, and steps S49 to S52 are repeated. When step S49 to step S51 are repeated a predetermined number of times (step S52; YES), the processing unit 17 performs propagation delay correction of the timer 16 (step S52). Thus, the propagation delay time for a predetermined number of times is calculated.

  The processing unit 17 predicts the propagation delay time when the oscillator 15 is stabilized from the predetermined number of propagation delay times (step S53), and corrects the propagation delay of the timer 16 based on the predicted propagation delay time. (Step S54), the process ends.

  The predetermined number of times may be a number enough to predict the synchronization time when the oscillator 15 is stabilized. Further, the processing unit 17 predicts the propagation delay time when the oscillator 15 is stabilized and performs propagation delay correction, and calculates an error due to the oscillator 15 not being stable based on the correction value of the propagation delay correction, Offset correction may be performed again.

  In the example of FIG. 7, step S49 to step S52 are repeated a predetermined number of times. At this time, the transmission unit 13 transmits a Delay Request Message to the master device M1 at a transmission interval shorter than normal time packet communication. Here, the transmission interval is the time from when the receiving unit 14 receives the Delay Response Message until the transmitting unit 13 transmits the next Delay Request Message.

  According to this embodiment, the propagation delay time is calculated a plurality of times before the oscillator 15 of the slave device is stabilized, and the propagation delay time when the oscillator 15 is stabilized is predicted from the transition of the propagation delay time. The time until the time synchronization can be further shortened.

  FIG. 8 is a flowchart illustrating an example of a time synchronization operation of a slave device according to another embodiment. In the embodiment of FIG. 8, the propagation delay time is repeatedly calculated before the oscillator 15 is stabilized, and the propagation delay is calculated when the difference between the previous propagation delay time and the current propagation delay time is equal to or less than the threshold value. The time calculation is repeated. Here, an example of the operation of time synchronization of the slave device S1 will be described. The slave devices S2 to SX perform the same time synchronization operation. At the same time as the power supply of the slave device S1 is activated, the counter 11 in the slave device S1 is activated (step S61), and count-up is started. If the counter value is not greater than or equal to N1 (step S62; NO), step S62 is repeated. The counter value N1 is a value indicating a time shorter than the time when the oscillator 15 is stabilized or a value indicating a time shorter than the time obtained by subtracting the shortest time for executing the determination process from the time when the oscillator 15 is stabilized.

  When the counter value is equal to or greater than N1 (step S62; YES), the determination unit 12 determines whether the master device M1 is in a busy state in which time synchronization is performed with another slave device (step S62). S63). If the determination unit 12 determines that the busy state is present (step S63; YES), step S63 is repeated until the busy state of the master device M1 is released. When the master apparatus M1 is not busy (step S63; NO), the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master apparatus M1 (step S64).

  When master device M1 receives Announce Message 1 from slave device S1, master device M1 transmits Announce Message 2 for obtaining an offset time difference between master device M1 and slave device S1 to slave device S1. At the same time, an Announce Message 3 indicating that the master device M1 is in a busy state is transmitted to the other slave devices. Alternatively, the master device M1 broadcasts an Announce Message 2 destined for the stave device S1 in order to notify other slave devices that time synchronization with the stave device S1 has started and is in a busy state. Also good. Then, the master device M1 transmits a Follow UP Message including the time when the Announce Message 2 is transmitted to the slave device S1.

  When the receiving unit 14 of the slave device S1 receives the Announce Message 2 from the master device M1 (Step S65) and receives a Follow UP Message including the time when the Announce Message 2 is transmitted from the master device M1 (Step S66), the processing unit 17 calculates an offset time difference based on the time when the Announce Message 2 is transmitted from the master device M1 included in the Follow UP Message and the time when the receiving unit 14 receives the Announce Message 2 (Step S67). Offset correction is performed (step S68).

  Next, the transmission unit 13 transmits a Delay Request Message for obtaining a propagation delay time between the master device M1 and the slave device S1 to the master device M1 at a transmission interval shorter than normal time packet communication (step S69). ). Here, the transmission interval is the time from when the receiving unit 14 receives the Follow UP Message to when the transmitting unit 13 transmits the Delay Request Message.

  When receiving the Delay Request Message from the slave device S1, the master device M1 transmits a Delay Response Message including the time when the Delay Request Message is received to the slave device S1. At the same time, Announce Message 3 indicating that the master device M1 is busy is transmitted to the other slave devices. Alternatively, the master device M1 may broadcast a Delay Response Message destined for the stave device S1 in order to notify other slave devices that it is busy for time synchronization with the stave device S1.

  When the reception unit 14 of the slave device S1 receives the Delay Response Message from the master device M1 (Step S70), the processing unit 17 transmits the time when the transmission unit 13 transmits the Delay Request Message and the master device M1 included in the Delay Response Message. The propagation delay time is calculated based on the time when the Delay Request Message is received (step S71). If the difference between the propagation delay time calculated last time and the propagation delay time calculated this time is not less than or equal to a threshold (for example, 1 second) (step S72; NO), the process returns to step S69, and steps S69 to S72 are repeated. When the difference between the propagation delay time calculated last time and the propagation delay time calculated this time is equal to or less than a threshold value (for example, 1 second) (step S72; YES), the processing unit 17 performs processing based on the propagation delay time calculated this time. Then, the propagation delay of the timer 16 is corrected (step S73), and the process is terminated.

  The threshold value determined in step S51 may be a value equal to or greater than 0 and within the allowable range of time synchronization accuracy that is obtained. Further, the processing unit 17 performs propagation delay correction based on the propagation delay time when the value converges, calculates an error due to the unstableness of the oscillator 15 based on the propagation delay correction value, and performs offset correction again. You may go.

  In the example of FIG. 8, step S69 to step S72 are repeated. At this time, the transmission unit 13 transmits a Delay Request Message to the master device M1 at a transmission interval shorter than normal time packet communication. Here, the transmission interval is the time from when the receiving unit 14 receives the Delay Response Message until the transmitting unit 13 transmits the next Delay Request Message.

  According to this embodiment, the propagation delay time is repeatedly calculated before the slave device oscillator 15 is stabilized, and the propagation delay time calculation is repeated when the propagation delay time value converges to a predetermined range. By ending, the time until time synchronization can be further shortened.

  FIG. 9 is a diagram illustrating time synchronization in an electronic device system according to another embodiment. An example of an operation flow of time synchronization in electronic device system 100 according to the present embodiment will be described using FIG. 9 with reference to the flowcharts of FIGS. In the example of FIG. 9, for convenience, the electronic device system 100 includes a master device 1, a slave device S1, and a slave device S2, and shows a case where time synchronization of the slave device S1 is executed.

  The slave device S1 is activated (step S41, step S61), the counter value of the counter 11 of the slave device S1 becomes N or more (step S42, step S62; YES), and the Announce Message 3 is not received (step S31; NO), when a predetermined time (12 seconds) elapses (step S33; NO), the determination unit 12 determines that the master device M1 is not busy (step S43, step S63; NO). At time 00:15 when the determination unit 12 determines that it is not busy, the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master device M1 (steps S44 and S64). When master device M1 receives Announce Message 1 at time 00:03, master device M1 provides Announce Message 2 for obtaining an offset time difference between master device M1 and slave device S1 to slave device S1 at time 00:04. Send. At the same time, an Announce Message 3 indicating that the master device M1 is busy is transmitted to the slave device S2. Then, a Follow UP Message including the time 00:04 at which the Announce Message 2 is transmitted is transmitted to the slave device S1 at the time 00:05.

  The receiving unit 14 of the slave device S1 receives the Announce Message 2 at time 00:22 (step S45, step S65), and receives a Follow UP Message at time 00:23 (step S46, step S66). Based on the time 00:22 when the receiving unit 14 receives the Announce Message 2 and the time 00:04 when the Announce Message 2 is transmitted from the master device included in the Follow UP Message, the processing unit 17 Offset time difference {00: 22−00: 04 = 00: 18} is calculated (step S47, step S67), and offset correction is performed by subtracting offset time difference 00:18 from time 00:23 to time 00:05. (Step S48, Step S68).

  Next, the transmission unit 13 of the slave device S1 transmits a Delay Request Message for obtaining a propagation delay time between the master device and the slave device to the master device M1 at time 00:06 after the offset correction (Step S49, Step S69). The master device transmits a Delay Response Message including time 00:12 at which the Delay Request Message is received to the slave device S1 at time 00:13.

  The receiving unit 14 of the slave device S1 receives the Delay Response Message at time 00:13 after the offset correction (Steps S50 and S70). Based on the time 00:06 after the offset correction when the transmission unit 13 transmitted the Delay Request Message and the time 00:12 when the master device M1 included in the Delay Response Message received the Delay Request Message, The propagation delay time {(00: 12-00: 06) / 2 = 00: 03} between the master device M1 and the slave device S1 is calculated (step S51, step S71).

  Here, the calculation of the propagation delay time is not repeated a predetermined number of times (twice) (step S52; NO), or there is no propagation delay time calculated last time (step S72; NO), so the transmission unit of the slave device S1 13 again transmits a Delay Request Message for obtaining the propagation delay time between the master device and the slave device to the master device M1 at time 00:13 after the offset correction (steps S49 and S69). The master device transmits a Delay Response Message including time 00:20 at which the Delay Request Message is received to the slave device S1 at time 00:21.

  The receiving unit 14 of the slave device S1 receives the Delay Response Message at time 00:21 after the offset correction (Steps S50 and S70). Based on the time 00:14 after offset correction when the transmission unit 13 transmits the Delay Request Message and the time 00:20 when the master device M1 included in the Delay Response Message receives the Delay Request Message, The propagation delay time {(00: 20-00: 14) / 2 = 00: 03} between the master device M1 and the slave device S1 is calculated (step S51, step S71).

  Since the calculation of the propagation delay time is repeated a predetermined number of times (twice) (step S52; YES), based on the propagation delay time 3 seconds calculated for the first time and the propagation delay time 3 seconds calculated for the second time. The propagation delay time when the oscillator 15 is stabilized is predicted to be 3 seconds (step S53).

  Alternatively, since the difference between the previously calculated propagation delay time of 3 seconds and the currently calculated propagation delay time of 3 seconds is equal to or less than the threshold (1 second) (step S72; YES), the propagation delay time is set to 3 seconds.

  The processing unit 17 performs propagation delay correction at time 00:26 by adding the propagation delay time 00:03 to time 00:23 after the offset correction (steps S54 and S73). Thus, time synchronization between the master device and the slave device is performed.

  On the other hand, the slave device S2 receives the master device at time 00:02 before a predetermined time (12 seconds) elapses after the counter value of the counter 11 becomes N or more (step S42, step S62; YES). Announce Message 3 is received from M1 (step S31; YES). Thereby, the determination part 12 determines with it being a busy state (step S32). Also, Announce Message 3 is received from master device M1 at time 00:13 before a predetermined time (12 seconds) elapses (step S31). Thereby, the determination part 12 determines with it being a busy state (step S32). Furthermore, the Announce Message 3 is received from the master device M1 at time 00:21 before a predetermined time (12 seconds) elapses (step S31). Thereby, the determination part 12 determines with it being a busy state (step S32). Then, since the Announce Message 3 has not been received by the time 00:33 when the predetermined time (12 seconds) elapses (step S33; YES), the determination unit 12 determines that the busy state of the master device M1 has been released. (Step S34). Since the determination unit 12 determines that it is not busy, the transmission unit 13 transmits Announce Message 1 for requesting the start of time synchronization to the master device M1 at time 00:34 (steps S44 and S64).

  FIG. 10 is a block diagram illustrating a hardware configuration example of the slave device according to the embodiment. As illustrated in FIG. 10, the slave devices S <b> 1 to SX include a control unit 31, a main storage unit 32, an external storage unit 33, an operation unit 34, a display unit 35, and an oscillator 36. The main storage unit 32, the external storage unit 33, the operation unit 34, the display unit 35, and the oscillator 36 are all connected to the control unit 31 via the internal bus 30.

  The control unit 31 includes a CPU (Central Processing Unit) and the like, and performs each process of the counter 11, the transmission unit 13, the reception unit 14, the timer 16, and the processing unit 17 in accordance with the control program 30 stored in the external storage unit 33. Run.

  The main storage unit 32 is constituted by a RAM (Random-Access Memory) or the like, loads the control program 30 stored in the external storage unit 33, and is used as a work area of the control unit 31.

  The external storage unit 33 includes a nonvolatile memory such as a flash memory, a hard disk, a DVD-RAM (Digital Versatile Disc Random-Access Memory), a DVD-RW (Digital Versatile Disc ReWritable), and performs processing of the slave devices S1 to SX. A program to be executed by the control unit 31 is stored in advance, and data stored by the program is supplied to the control unit 31 in accordance with an instruction from the control unit 31, and the data supplied from the control unit 31 is stored.

  The operation unit 34 includes a pointing device such as a keyboard and a numeric keypad, and an interface device that connects the keyboard, numeric keypad, and the like to the internal bus 30. Furthermore, the operation unit 34 may include a voice input device. When the user inputs the counter value N or the threshold time synchronization interval α, an instruction is supplied to the control unit 31 via the operation unit 34.

  The display unit 35 is configured by a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like, and displays information sent from the control unit 31. When the user inputs the counter value N or the threshold time synchronization interval α, the display unit 35 displays an operation screen.

  The oscillator 37 generates a clock having a predetermined frequency and supplies it to the control unit 31. The oscillator 37 functions as the oscillator 15.

  The processing of the counter 11, the transmission unit 13, the reception unit 14, the oscillator 15, the timer 16, and the processing unit 17 of the slave device S1 (slave devices S2 to SX) illustrated in FIG. The processing is executed by using the unit 32, the external storage unit 33, the operation unit 34, the display unit 35, the oscillator 36, the oscillator 37, and the like as resources.

  In addition, the hardware configuration and the flowchart described above are merely examples, and can be arbitrarily changed and modified.

  The central part that performs the time synchronization process including the control unit 31, the main storage unit 32, the external storage unit 33, the operation unit 34, the internal bus 30 and the like uses a normal computer system, not a dedicated system. Is feasible. For example, a computer program for executing the above operation is stored and distributed in a computer-readable recording medium (flexible disk, CD-ROM, DVD-ROM, etc.), and the computer program is installed in the computer. Thus, the slave devices S1 to SX that execute the above-described processing may be configured. In addition, the slave device S1 to SX may be configured by storing the computer program in a storage device included in a server device on a communication network such as the Internet and downloading the normal computer system.

  Further, when the functions of the slave devices S1 to SX are realized by sharing an OS (operating system) and an application program or by cooperation between the OS and the application program, only the application program portion is stored in a recording medium or a storage device. It may be stored.

  It is also possible to superimpose a computer program on a carrier wave and distribute it via a communication network. For example, the computer program may be posted on a bulletin board (BBS, Bulletin Board System) on a communication network, and the computer program may be distributed via the network. The computer program may be started and executed in the same manner as other application programs under the control of the OS, so that the above-described processing may be executed.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
A slave device that performs time synchronization with a master device via a network,
A timer for generating time information;
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals;
A determination means for determining whether or not the master device is busy performing time synchronization with other slave devices when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. One receiving means;
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. When,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. A transmission means;
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means,
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
A slave device comprising:

(Appendix 2)
The second transmission means transmits the third message to the master device;
The second receiving means receives the fourth message from the master device; and
The propagation time based on the time when the delay time calculating means transmits the third message by the second transmitting means and the time when the master device receives the third message included in the fourth message. Calculate the time,
Repeat the propagation delay time calculation process at a predetermined cycle,
The slave device according to appendix 1, wherein the correction unit corrects the time of the timer based on the offset time difference and the plurality of propagation delay times calculated by the propagation delay time calculation process.

(Appendix 3)
Predicting means for predicting the propagation delay time when the oscillator is stable based on the plurality of propagation delay times calculated by repeating the propagation delay time calculating process and performing the propagation delay time calculating process a predetermined number of times. In addition,
The slave device according to appendix 2, wherein the correction unit corrects the time of the timer based on the offset time difference and the propagation delay time predicted by the prediction unit.

(Appendix 4)
When the propagation delay time calculation process is repeated, and the difference between the propagation delay time calculated in the propagation delay time calculation process and the propagation delay time calculated before is less than or equal to a threshold value,
3. The slave device according to appendix 2, wherein the correcting unit corrects the time of the timer based on the offset time difference and the last calculated propagation delay time.

(Appendix 5)
2. The slave device according to claim 1, wherein the predetermined value is a value of the counter that represents a time indicating that the oscillator is stabilized after the slave device is activated.

(Appendix 6)
An electronic device system including a master device that performs time synchronization via a network and two or more slave devices,
Each of the slave devices is
A timer that generates time information,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
Including
The master device is
Third receiving means for receiving the first message from the slave device;
When the third receiving unit receives the first message from the slave device, the second message and the follow-up message are transmitted to the target slave device that is the slave device of the other party that received the first message. Third transmitting means for
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
Fourth receiving means for receiving the third message from the target slave device; and
Fifth transmission means for transmitting the fourth message to the target slave device when the fourth reception means receives the third message from the target slave device;
An electronic device system comprising:

(Appendix 7)
A master device that performs time synchronization with two or more slave devices via a network,
Third receiving means for receiving a first message for requesting start of time synchronization from the slave device;
When the third receiving unit receives the first message from the slave device, the third receiving unit includes a second message for obtaining an offset time difference between the master device and the slave device, and a time when the second message is transmitted. A third transmission means for transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
A fourth receiving means for receiving a third message for obtaining a propagation delay time between the master device and the slave device from the target slave device;
When the fourth receiving unit receives the third message from the target slave device, a fifth transmitting unit that transmits a fourth message including the time when the third message is received to the target slave device;
A master device comprising:

(Appendix 8)
The appendix 7 according to appendix 7, wherein the fourth transmitting unit transmits the fifth message to the slave device other than the target slave device every time the fifth transmitting unit transmits the fourth message. Master device.

(Appendix 9)
In an electronic device system including a master device that performs time synchronization via a network and two or more slave devices, the oscillator includes a clock that generates a clock for generating time information, and a counter that counts up at a predetermined interval A determination step of determining whether or not the master device is busy performing time synchronization with another slave device when the value of the counter executed by the slave device exceeds a predetermined value;
A first transmission step of transmitting a first message requesting the master device to start time synchronization when it is determined that the busy state is not determined in the determination step;
A third receiving step for receiving the first message from the slave device, which is executed by the master device;
When the first message is received from the slave device in the third receiving step, a second message for obtaining an offset time difference between the master device and the slave device and a time at which the second message is transmitted are included. A third transmission step of transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission step of transmitting a fifth message indicating the busy state to the slave device other than the target slave device when the second message is transmitted to the target slave device in the third transmission step;
A first receiving step of receiving the second message and the follow-up message from the master device, executed by the target slave device;
Offset calculating step for calculating the offset time difference based on the time when the second message is received in the first receiving step and the time when the second message included in the follow-up message is transmitted from the master device. When,
A second message for transmitting a third message for determining a propagation delay time between the master device and the slave device after receiving the follow-up message from the master device in the first receiving step; Sending step;
A fourth reception step of receiving the third message from the target slave device, executed by the master device;
When receiving the third message from the target slave device in the fourth reception step, a fifth transmission step of transmitting the fourth message including the time when the third message is received to the target slave device;
A second receiving step for receiving the fourth message from the master device, executed by the target slave device;
A delay time calculating step of calculating the propagation delay time based on a time when the third message is transmitted and a time when the master device receives the third message included in the fourth message;
A correction step of correcting the time of the timer based on the offset time difference and the propagation delay time;
A time synchronization method comprising:

(Appendix 10)
The second transmission step executed by the slave device;
The fourth receiving step executed by the master device;
The fifth transmission step;
The second receiving step executed by the target slave device;
The delay time calculating step;
The propagation delay time calculation process including is repeated at a predetermined cycle,
The time synchronization method according to appendix 9, wherein in the correction step, the time of the timer is corrected based on the offset time difference and the plurality of propagation delay times calculated in the propagation delay time calculation process. .

(Appendix 11)
Predicting the propagation delay time when the oscillator is stabilized based on the plurality of propagation delay times calculated by repeating the propagation delay time calculation process and performing the propagation delay time calculation process a predetermined number of times. In addition,
The time synchronization method according to claim 10, wherein in the correction step, the time of the timer is corrected based on the offset time difference and the propagation delay time predicted by the prediction means.

(Appendix 12)
When the propagation delay time calculation process is repeated, and the difference between the propagation delay time calculated in the propagation delay time calculation process and the propagation delay time calculated before is less than or equal to a threshold value,
The time synchronization method according to claim 10, wherein in the correction step, the time of the timer is corrected based on the offset time difference and the propagation delay time calculated last.

(Appendix 13)
The time synchronization method according to claim 9, wherein the predetermined value is a value of the counter indicating a time indicating that the oscillator is stabilized after the slave device is activated.

(Appendix 14)
In the fourth transmission step, the fifth message is transmitted to the slave device other than the target slave device every time the fourth message is transmitted in the fifth transmission step. The time synchronization method described.

(Appendix 15)
A timer that generates time information for the computer,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
A program characterized by functioning as

M1 Master device S1, S2, SX Slave device
11 counter
12 Judgment part
13 Transmitter
14 Receiver
15 Oscillator
16 timer
17 Processing section
31 Control unit
32 Main memory
33 External storage
34 Operation unit
35 Display section
36 Oscillator
100 Electronic equipment system

Claims (10)

A slave device that performs time synchronization with a master device via a network,
A timer for generating time information;
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals;
A determination means for determining whether or not the master device is busy performing time synchronization with other slave devices when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. One receiving means;
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. When,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. A transmission means;
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means,
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
A slave device comprising: The second transmission means transmits the third message to the master device;
The second receiving means receives the fourth message from the master device; and
The propagation time based on the time when the delay time calculating means transmits the third message by the second transmitting means and the time when the master device receives the third message included in the fourth message. Calculate the time,
Repeat the propagation delay time calculation process at a predetermined cycle,
2. The slave device according to claim 1, wherein the correction unit corrects the time of the timer based on the offset time difference and the plurality of propagation delay times calculated by the propagation delay time calculation process. . Predicting means for predicting the propagation delay time when the oscillator is stable based on the plurality of propagation delay times calculated by repeating the propagation delay time calculating process and performing the propagation delay time calculating process a predetermined number of times. In addition,
The slave device according to claim 2, wherein the correction unit corrects the time of the timer based on the offset time difference and the propagation delay time predicted by the prediction unit. When the propagation delay time calculation process is repeated, and the difference between the propagation delay time calculated in the propagation delay time calculation process and the propagation delay time calculated before is less than or equal to a threshold value,
The slave device according to claim 2, wherein the correction unit corrects the time of the timer based on the offset time difference and the propagation delay time calculated last.   2. The slave device according to claim 1, wherein the predetermined value is a value of the counter representing a time indicating that the oscillator is stabilized after the slave device is activated. An electronic device system including a master device that performs time synchronization via a network and two or more slave devices,
Each of the slave devices is
A timer that generates time information,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
Including
The master device is
Third receiving means for receiving the first message from the slave device;
When the third receiving unit receives the first message from the slave device, the second message and the follow-up message are transmitted to the target slave device that is the slave device of the other party that received the first message. Third transmitting means for
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
Fourth receiving means for receiving the third message from the target slave device; and
Fifth transmission means for transmitting the fourth message to the target slave device when the fourth reception means receives the third message from the target slave device;
An electronic device system comprising: A master device that performs time synchronization with two or more slave devices via a network,
Third receiving means for receiving a first message for requesting start of time synchronization from the slave device;
When the third receiving unit receives the first message from the slave device, the third receiving unit includes a second message for obtaining an offset time difference between the master device and the slave device, and a time when the second message is transmitted. A third transmission means for transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission unit configured to transmit a fifth message indicating the busy state to the slave device other than the target slave device when the third transmission unit transmits the second message to the target slave device;
A fourth receiving means for receiving a third message for obtaining a propagation delay time between the master device and the slave device from the target slave device;
When the fourth receiving unit receives the third message from the target slave device, a fifth transmitting unit that transmits a fourth message including the time when the third message is received to the target slave device;
A master device comprising:   The said 4th transmission means transmits the said 5th message to said slave apparatuses other than the said target slave apparatus, whenever the said 5th transmission means transmits the said 4th message. Master device. In an electronic device system including a master device that performs time synchronization via a network and two or more slave devices, the oscillator includes a clock that generates a clock for generating time information, and a counter that counts up at a predetermined interval A determination step of determining whether or not the master device is busy performing time synchronization with another slave device when the value of the counter executed by the slave device exceeds a predetermined value;
A first transmission step of transmitting a first message requesting the master device to start time synchronization when it is determined that the busy state is not determined in the determination step;
A third receiving step for receiving the first message from the slave device, which is executed by the master device;
When the first message is received from the slave device in the third receiving step, a second message for obtaining an offset time difference between the master device and the slave device and a time at which the second message is transmitted are included. A third transmission step of transmitting a follow-up message to a target slave device that is the slave device of the other party that received the first message;
A fourth transmission step of transmitting a fifth message indicating the busy state to the slave device other than the target slave device when the second message is transmitted to the target slave device in the third transmission step;
A first receiving step of receiving the second message and the follow-up message from the master device, executed by the target slave device;
Offset calculating step for calculating the offset time difference based on the time when the second message is received in the first receiving step and the time when the second message included in the follow-up message is transmitted from the master device. When,
A second message for transmitting a third message for determining a propagation delay time between the master device and the slave device after receiving the follow-up message from the master device in the first receiving step; Sending step;
A fourth reception step of receiving the third message from the target slave device, executed by the master device;
When receiving the third message from the target slave device in the fourth reception step, a fifth transmission step of transmitting the fourth message including the time when the third message is received to the target slave device;
A second receiving step for receiving the fourth message from the master device, executed by the target slave device;
A delay time calculating step of calculating the propagation delay time based on a time when the third message is transmitted and a time when the master device receives the third message included in the fourth message;
A correction step of correcting the time of the timer based on the offset time difference and the propagation delay time;
A time synchronization method comprising: A timer that generates time information for the computer,
An oscillator for generating a clock for generating the time information;
A counter that counts up at predetermined intervals,
A determination unit that determines whether or not the master device is busy performing time synchronization with another slave device when the value of the counter exceeds a predetermined value;
A first transmission unit configured to transmit a first message requesting the master device to start time synchronization when the determination unit determines that the busy state is not present;
A second message for receiving an offset time difference between the master device and the slave device and a follow-up message including a time when the second message is transmitted from the master device from the master device. 1 receiving means,
Offset calculating means for calculating the offset time difference based on the time when the first receiving means receives the second message and the time when the second message included in the follow-up message is transmitted from the master device. ,
After the first receiving means receives the follow-up message from the master device, a second message is transmitted to the master device for determining a propagation delay time between the master device and the slave device. Transmission means,
Second receiving means for receiving a fourth message including a time at which the master device has received the third message from the master device;
Delay time calculation for calculating the propagation delay time based on the time at which the second transmission means transmits the third message and the time at which the master device receives the third message included in the fourth message. Means and
Correction means for correcting the time of the timer based on the offset time difference and the propagation delay time;
A program characterized by functioning as

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