TWI599863B - Time synchronization device, time synchronization system and time synchronization method - Google Patents

Description

Time synchronization device, time synchronization system, and time synchronization method

The present invention relates to a time synchronization device, a time synchronization system, and a time synchronization method.

In the field of PA (Process‧Automation), we have promoted intelligent communication in a wide area by transforming from a closed network to an open network and the application of new information technologies. As a specific example, for example, a smart grid can be mentioned. In the measurement and control of most devices, in order to simplify event synchronization and data correlation, high-accuracy time synchronization is required.

In the closed network configuration, a so-called dozens of relatively few devices are synchronized at a time by the unique time synchronization method. The time synchronization accuracy is in microsecond units. In order to improve the accuracy of time synchronization, the time synchronization method is mainly installed on a hardware substrate.

As a time synchronization method that can be utilized in an open network, IEEE (Institute‧of‧Electrical‧and‧Electronics‧Eengineers; Institute of Electrical and Electronics Engineers) developed the time synchronization specification IEEE1588 using Ethernet (trademark registration) . In IEEE 1588, a method of synchronizing a time by transmitting/receiving a synchronization frame at a recorded time through a network is defined. The IEEE1588 is divided into two types: hardware base mounting and software base mounting.

In a hardware base installation, use OSI (Open‧ Systems‧Interconnection; Open System Interconnection) The hard time stamp function of the physical layer processing PHY of the reference model, recording time (for example, refer to Patent Document 1). Therefore, the time transmission side records the time stamp when the PHY transmits the synchronization frame as the transmission time, and transmits the recorded transmission time. Similarly, the time receiving side records the time stamp when the PHY receives the synchronization frame as the reception time, and uses the recorded reception time for the application. The timing synchronization accuracy is theoretically 1 nanosecond, but in reality it is up to 100 nanoseconds.

In the software base installation, the software time stamp function of the application layer processing of the OSI reference model is used to record the time. Therefore, the time transmission side records the time stamp when the application indicates the transmission of the synchronization frame by the lower processing as the transmission time, and transmits the recorded transmission time. Similarly, the time receiving side records the time stamp when the application is notified of the reception of the synchronization frame from the lower processing as the reception time, and uses the recorded reception time for the application. The time synchronization accuracy is deteriorated to the extent of 100 milliseconds in the worst case. Moreover, the timing synchronization accuracy of the software base mounting greatly varies depending on the OS (Operating‧System; operating system) in which the application operates and the hierarchical structure of the communication function.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-256965

When the system is changed from a closed network to an open network, Connect the system to other systems. From the point of view of asset exchange, it is continued to utilize the existing time synchronization method in the time synchronization within the system, and it is considered that IEEE1588 can be utilized when synchronizing with the time outside the system. However, in this case, it is necessary to have a terminal corresponding to the existing time synchronization method and IEEE1588. In the case of re-importing IEEE1588, if it is mounted on a hard substrate, high-accuracy time synchronization can be obtained, but it is costly. Therefore, from the viewpoint of cost saving, it is expected to use a software substrate installation.

The invention aims to improve the time synchronization accuracy according to the time synchronization manner of the software substrate installation.

A time synchronization device according to an aspect of the present invention includes: a receiving unit that receives first data from a master device having a master clock; and a transmitting unit that transmits the second data to the aforementioned information after receiving the first data according to the receiving unit a recording unit that records the first data reception time of the receiving unit and the second data transmission time of the transmission unit using a slave clock of the software clock, and a correction unit that corrects the first record recorded by the recording unit And a synchronization unit that corrects at least the first data transmission time of the master device notified by the master device, the first data reception time corrected by the correction unit, and the correction according to the correction The second data transmission time of the partial correction and the second data reception time of the master device notified by the master device calculate an offset of the time difference between the master device clock and the slave clock.

In the present invention, since the timing of recording using the software clock is corrected, the time synchronization accuracy according to the time synchronization manner of the software substrate mounting can be improved.

100‧‧‧Time synchronization system

101‧‧‧First Time Synchronization

102‧‧‧Second Time Synchronization Mode

110‧‧‧GM (main master)

120‧‧‧PLC (programmable logic controller)

130‧‧‧Field devices

200‧‧‧Main device

201‧‧‧Master Clock

202‧‧‧PHY (Port‧Physical‧Layer;埠Physical layer)

203‧‧‧MAC (Media Access Controller)

204‧‧‧MAC drive

205‧‧‧OS (Operating System)

206‧‧‧Time synchronization application

207‧‧‧Other applications

208‧‧‧Revised form

210‧‧‧Transportation Department

220‧‧‧ Receiving Department

230‧‧ ‧Recording Department

240‧‧‧Revision Department

300‧‧‧Time synchronization device

301‧‧‧Subordinate clock

302‧‧‧PHY

303‧‧‧MAC

304‧‧‧MAC drive

305‧‧‧OS

306‧‧‧Time synchronization application

307‧‧‧Other applications

308‧‧‧Revision Table

310‧‧‧ Receiving Department

320‧‧‧Transportation Department

330‧‧‧Recording Department

340‧‧‧Revision Department

350‧‧‧Synchronization Department

400‧‧‧Network

401‧‧‧1st information

402‧‧‧2nd information

403‧‧‧3rd information

404‧‧‧4th information

405‧‧‧Offset

901‧‧‧ processor

902‧‧‧Auxiliary memory device

903‧‧‧ memory

904‧‧‧Communication device

905‧‧‧Input interface

906‧‧‧Display interface

907‧‧‧ Input device

908‧‧‧ display

910‧‧‧ signal line

911‧‧‧Wire

912‧‧‧Wire

921‧‧‧ Receiver

922‧‧‧transmitter

Fig. 1 is a view showing a configuration example of a time synchronization system according to the first embodiment.

Fig. 2 is a block diagram showing the configuration of a master device and a time synchronization device according to the first embodiment.

Fig. 3 is a flow chart showing the operation of the time synchronization system according to the first embodiment.

Fig. 4 is a flow chart showing the operation of the time synchronization system according to the first embodiment.

Fig. 5 is a flow chart showing the operation of the time synchronization system according to the first embodiment.

Fig. 6 is a block diagram showing an example of mounting of a master device and a time synchronization device according to the first embodiment.

Fig. 7 is a sequence diagram showing communication means between the master device and the time synchronization device in the first embodiment.

Fig. 8 is a view showing a configuration example of a time synchronization system according to the second embodiment.

Fig. 9 is a view showing a configuration example of a time synchronization system according to the third embodiment.

Figure 10 is a view showing the timing of the time synchronization device according to the embodiment of the present invention. The figure of the body composition example.

Hereinafter, embodiments of the present invention will be described using the drawings. In the drawings, the same or corresponding parts are attached to the same symbols. In the description of the embodiments, the description of the same or equivalent components will be omitted or simplified.

Embodiment 1.

In the conventional time synchronization method in which the software base is mounted, there is a problem that the aforementioned time synchronization accuracy is deteriorated. This problem is mainly due to the fluctuation of the software time stamp and the asymmetry of the internal processing delay of the terminal at the time of installation. In the present embodiment, at least a part of these main factors can be removed or suppressed by correcting the recorded value at the time.

In the present embodiment, it is possible to realize time synchronization in a distributed system in which a plurality of devices exist by mounting on a soft substrate. In the time synchronization method according to the present embodiment in which the software base is mounted, the principle of IEEE 1588 is utilized. This time synchronization method can be installed in any terminal existing in the distributed system. The OS installed on the terminal is an instant OS. The terminal on the transmission side is the master device. The terminal on the receiving side of time is a slave that is dependent and synchronized at the time of implementation.

Hereinafter, the system configuration of the present embodiment, the system operation of the present embodiment, and the effects of the present embodiment will be described in order.

***Composed description***

An example of the configuration of the time synchronization system 100 according to the system of the present embodiment will be described with reference to Fig. 1 .

The time synchronization system 100 is a distributed system. Time synchronization system 100 It includes: one GM110 (Grand. Master; main master), and a plurality of PLC120 (Programmable‧Logic‧ Controller; programmable logic controller), and a plurality of field devices 130.

In this case, a tree-like network architecture is used. The GM 110 becomes the root, and at least three PLCs 120 are connected to the GM 110 as the lower node of the root. At least one PLC 120 or at least three field devices 130 are connected as lower-level nodes to form a sub-network.

The GM110 provides a time base. The first time synchronization method 101 is applied to the time synchronization between the GM 110 and the PLC 120 connected to the GM 110. The first time synchronization method 101 is a time synchronization method according to the present embodiment and is based on the principle of IEEE1588. The sequence of time synchronization according to the first time synchronization method 101 will be described in detail later.

The second time synchronization method 102 is applied to time synchronization in each subnet. The second time synchronization method 102 is an individual time synchronization method for each subnet. The order of the time synchronization according to the second time synchronization method 102 can be applied to any order, and the description thereof will be omitted.

The PLC 120 connected to the GM 110 corresponds to the second time synchronization method 102 of each subnet, and also corresponds to the first time synchronization method 101.

Further, the number of PLCs 120 connected to the GM 110 and the configuration of each subnet can be changed as appropriate. It is also possible to replace the PLC 120 with another type of machine such as NC (Numerical ‧ Controller; numerical controller).

The configuration of the main device 200 and the time synchronization device 300 according to the present embodiment will be described with reference to Fig. 2 .

The main device 200 has a main clock 201. The main clock 201 is not a hardware clock but a software clock. The so-called hardware clock is a clock that is mounted on a hardware. The hardware clock is used for hardware time stamping. The so-called software clock is a clock that is managed by software. The software clock is utilized for the software timestamp function.

The main apparatus 200 includes a transmission unit 210, a reception unit 220, a recording unit 230, and a correction unit 240.

The GM 110 shown in FIG. 1 is a terminal on the transmission side in the first time synchronization method 101, and corresponds to the master device 200.

The time synchronization device 300 has a slave clock 301. The slave clock 301 is the same as the master clock 201 and is not a hardware clock but a software clock.

The time synchronization device 300 includes a reception unit 310, a transmission unit 320, a recording unit 330, a correction unit 340, and a synchronization unit 350.

The PLC 120 connected to the GM 110 as shown in FIG. 1 is a terminal on the receiving side at the time of the first time synchronization method 101, and corresponds to the time synchronization device 300.

The main device 200 and the time synchronization device 300 transmit and receive data to and from each other via the network 400 in accordance with the communication sequence of the first time synchronization method 101 described below. Thereby, the time synchronization device 300 can match the time of the slave clock 301 with the time of the master clock 201.

The transfer unit 210 of the host device 200 transmits the first material 401 to the time synchronization device 300.

The receiving unit 310 of the time synchronization device 300 receives the first material 401 from the host device 200.

The transmitting unit 320 of the time synchronization device 300 is using the receiving unit 310. After receiving the first material 401, the second material 402 is transmitted to the host device 200.

The receiving unit 220 of the host device 200 receives the second material 402 from the time synchronization device 300.

The recording unit 230 of the main device 200 uses the main clock 201 to record the transmission time of the first data 401 of the transmission unit 210 and the reception time of the second data 402 of the reception unit 220.

The correction unit 240 of the main device 200 corrects the transmission time of the first data 401 and the reception time of the second data 402 recorded by the recording unit 230.

The transmission unit 210 of the host device 200 notifies at least the third data 403 for transmitting the time of the first data 401 corrected by the correction unit 240, and at least the fourth time for receiving the second data 402 corrected by the correction unit 240. The data 404 is transmitted to the time synchronization device 300. Thereby, the transmission unit 210 notifies the time synchronization device 300 of at least the first data 401 transmission time and the second data 402 reception time corrected by the correction unit 240.

The receiving unit 310 of the time synchronization device 300 receives the third data 403 and the fourth material 404 from the host device 200.

The recording unit 330 of the time synchronization device 300 uses the slave clock 301 to record the reception time of the first data 401 of the reception unit 310 and the transmission time of the second data 402 of the transmission unit 320.

The correction unit 340 of the time synchronization device 300 corrects the reception time of the first data 401 and the transmission time of the second material 402 recorded by the recording unit 330.

The synchronization unit 350 of the time synchronization device 300 transmits at least the time of transmission of the first data 401 of the host device 200 notified by the host device 200, the time of reception of the first data 401 corrected by the correction unit 340, and the second resource corrected by the correction unit 340. The time 402 and the time of reception of the second data 402 of the host device 200 notified by the host device 200 are calculated, and the offset 405 is calculated. The offset 405 is offset from the time of the master clock 201 and the slave clock 301. When calculating the offset 405, the synchronization unit 350 refers to the third data 403 and the fourth material 404 received by the receiving unit 310. In other words, the synchronization unit 350 obtains the transmission timing of the first material 401 of the host device 200 from the third data 403 received by the reception unit 310. The synchronization unit 350 obtains the second data 402 reception time of the host device 200 from the fourth data 404 received by the reception unit 310.

In the present embodiment, the third data 403 is not only the transmission time of the first material 401 corrected by the correction unit 240 of the host device 200, but also for notifying the transmission time of the first data 401 recorded by the recording unit 230 of the host device 200. data. The fourth material 404 is not only the reception time of the second data 402 corrected by the correction unit 240, but also the data for notifying the reception time of the second data 402 recorded by the recording unit 230. In other words, in the present embodiment, the transmission unit 210 of the host device 200 further notifies the time synchronization device 300 of the transmission time of the first data 401 and the reception time of the second data 402 recorded by the recording unit 230. Therefore, when the offset unit 405 calculates the offset 405, the synchronization unit 350 of the time synchronization device 300 calculates the first data 401 transmission time recorded by the recording unit 230 of the main device 200 and the first data 401 corrected by the correction unit 240 of the main device 200. Both of the transfer times are used as the first data 401 transfer time of the host device 200 notified by the host device 200. Further, when the offset unit 405 calculates the offset 405, the synchronization unit 350 of the time synchronization device 300 receives the second data 402 reception time recorded by the recording unit 230 of the main device 200 and the second data 402 corrected by the correction unit 240 of the main device 200. At the time, both are used as the second data 402 of the main device 200 notified by the main device 200. Receive time.

In the present embodiment, when the offset unit 405 calculates the offset 405, the synchronization unit 350 not only receives the time of receiving the first data 401 corrected by the correction unit 340, but also receives the time of the first data 401 recorded by the recording unit 330. Further, when the offset unit 405 calculates the offset 405, the synchronization unit 350 not only transmits the time of the second data 402 corrected by the correction unit 340, but also transmits the time of the second material 402 recorded by the recording unit 330.

In other words, in the present embodiment, the synchronization unit 350 transmits the time from the first data 401 recorded by the host device 200, the transmission time of the first data 401 corrected by the main device 200, and the reception time of the first data 401 recorded by the recording unit 330, based on The first data 401 reception time corrected by the correction unit 340, the second data 402 transmission time recorded by the recording unit 330, the second data 402 transmission time corrected by the correction unit 340, and the second data 402 transmission time recorded by the host device 200, And the time at which the second data 402 corrected by the main device 200 is received, the offset 405 is calculated.

Specifically, the synchronization unit 350 receives the total of the transmission time of the first data 401 recorded by the host device 200 and the transmission time of the first data 401 corrected by the host device 200, and the reception time and the basis of the first data 401 recorded by the recording unit 330. The total difference between the reception time of the first data 401 corrected by the correction unit 340, and the total of the transmission time of the second data 402 recorded by the recording unit 330 and the transmission time of the second data 402 corrected by the correction unit 340, and the master device The offset 405 is calculated by the difference between the reception time of the second data 402 recorded at 200 and the reception time of the second data 402 corrected by the host device 200.

Further, the third material 403 may be used to notify the data transmitted at the time of the first data 401 recorded by the recording unit 230 of the host device 200. The fourth material 404 may be used to notify the data of the time of receipt of the second data 402 recorded by the recording unit 230. Therefore, the main device 200 does not include the correction unit 240.

When the main device 200 does not include the correction unit 240 or the correction unit 240 does not correct the transmission time of the first data 401 recorded by the recording unit 230, the correction unit 340 of the time synchronization device 300 corrects the main device 200 notified by the main device 200. The first data 401 can also be transmitted at the time. In this case, when the synchronization unit 350 of the time synchronization device 300 calculates the offset 405, the first data 401 of the main device 200 notified by the host device 200 can be used to transmit the time, and the first data 401 corrected by the correction unit 340 can be used. The moment of transmission.

When the main device 200 does not include the correction unit 240 or the correction unit 240 does not correct the reception time of the second data 402 recorded by the recording unit 230, the correction unit 340 of the time synchronization device 300 corrects the main device 200 notified by the main device 200. The second data 402 can also be received at the time. In this case, when the synchronization unit 350 of the time synchronization device 300 calculates the offset 405, the second data 402 that is corrected by the main device 200 can be used, and the second data 402 corrected by the correction unit 340 can be used. Receive time.

*** Action Description ***

The operation of the time synchronization system 100 will be described with reference to Figs. 3, 4 and 5. The operation of the time synchronization system 100 corresponds to the time synchronization method of the present embodiment.

FIG. 3 is a view showing an operation related to transmission/reception of the first material 401. In the present embodiment, transmission/reception of the first material 401 is repeated.

In step S11, the transmission unit 210 of the main device 200 will be the first The data 401 is repeatedly transmitted to the time synchronization device 300.

In step S12, the receiving unit 310 of the time synchronization device 300 repeatedly receives the first material 401 from the host device 200.

In step S13, the recording unit 230 of the main apparatus 200 records the transmission time of the first material 401 of the transmission unit 210 using the main clock 201 each time the first data 401 is transmitted by the transmission unit 210.

In step S14, the correction unit 240 of the main apparatus 200 generates a random number every time the recording unit 230 records the transmission time of the first material 401, and calculates the first data recorded by the recording unit 230 using the generated random number. 401 The correction value of the transmission time.

In step S15, the transmission unit 210 of the host device 200 transmits the data for notifying the correction value of the transmission time of the first data 401 calculated by the correction unit 240 to the time synchronization device 300 as the third data 403.

In step S16, the receiving unit 310 of the time synchronization device 300 repeatedly receives the third material 403 from the host device 200.

In step S17, the recording unit 330 of the time synchronization device 300 records the first data reception time of the reception unit 310 using the slave clock 301 each time the first data 401 is received by the reception unit 310.

In step S18, the correction unit 340 of the time synchronization device 300 generates a random number each time the reception time of the first data 401 is recorded by the recording unit 330, and calculates the first data recorded by the recording unit 330 using the generated random number. 401 receives the correction value of the time.

As will be described later, the synchronization unit 350 of the time synchronization device 300 uses the first data 401 calculated by the correction unit 340 when calculating the offset 405. The correction value at the time of collection is used as the reception time of the first material 401.

FIG. 4 is a view showing an operation related to transmission/reception of the second material 402. In the present embodiment, transmission/reception of the second material 402 is repeated.

In step S21, the transmission unit 320 of the time synchronization device 300 transmits the second material 402 to the main device 200 every time the reception unit 310 receives the first material 401.

In step S22, the receiving unit 220 of the host device 200 repeatedly receives the second material 402 from the time synchronization device 300.

In step S23, the recording unit 230 of the main device 200 records the reception time of the second material 402 of the receiving unit 220 using the main clock 201 each time the second data 402 is received by the receiving unit 220.

In step S24, the correction unit 240 of the main apparatus 200 generates a random number every time the recording unit 230 records the reception time of the second material 402, and calculates the second material 402 recorded by the recording unit 230 using the generated random number. The correction value at the time of reception.

In step S25, the transfer unit 210 of the host device 200 transmits the data for notifying the correction value of the second data 402 reception time calculated by the correction unit 240 to the time synchronization device 300 as the fourth data 404.

In step S26, the receiving unit 310 of the time synchronization device 300 repeatedly receives the fourth material 404 from the host device 200.

In step S27, the recording unit 330 of the time synchronization device 300 uses the slave clock 301 to record the transmission time of the second material 402 of the transmission unit 320 each time the second data 402 is transmitted by the transmission unit 320.

In step S28, the correction unit 340 of the time synchronization device 300 Each time the recording unit 330 records the transmission time of the second material 402, a random number is generated, and the correction value according to the transmission timing of the second material 402 recorded by the recording unit 330 is calculated using the generated random number.

As will be described later, the synchronization unit 350 of the time synchronization device 300 uses the correction value of the transmission time of the second data 402 calculated by the correction unit 340 as the transmission time of the second material 402 when calculating the offset 405.

In the present embodiment, as described above, the communication sequence in which one piece of the first material 401, the second material 402, the third material 403, and the fourth material 404 are sequentially transmitted/received is repeatedly performed.

FIG. 5 is a diagram showing the operation of calculating the offset 405.

In step S31, the synchronization unit 350 of the time synchronization device 300 calculates the offset 405 every time the first data 401 is received by the receiving unit 310. That is, the synchronization unit 350 calculates one offset 405 for one communication sequence.

In step S32, the synchronization unit 350 of the time synchronization device 300 stores a plurality of calculated values of the offset 405. In other words, the synchronization unit 350 stores two or more offsets 405 corresponding to the communication order of two or more times.

In step S33, the synchronization unit 350 of the time synchronization device 300 performs statistical processing of the plurality of stored calculated values. The synchronization unit 350 adjusts the timing of the slave clock 301 as a result of the statistical processing. Specifically, the synchronization unit 350 uses the average of the stored plurality of calculated values as the result of the statistical processing, and adjusts the timing of the slave clock 301. Thereby, the timing of the master clock 201 is synchronized with the timing of the slave clock 301.

In the present embodiment, as described above, the principle of IEEE 1588 is utilized. That is, the first data 401, the second data 402, the third data 403, and The fourth data 404 is transmitted/received as a synchronization frame. Specifically, the first data 401 is transmitted/received as a Sync message, the second data 402 is transmitted/received as a Follow-Up message, and the third data 403 is transmitted as a Delay_Req message. /Receive, the 4th data 404 is transmitted/received as a Delay_Resp message.

If it is assumed that the one-way delay between the master device 200 and the time synchronization device 300 is half of the round trip delay, the total time of the reception time of the first data 401 recorded by the recording unit 330 and the reception time of the first data 401 corrected by the correction unit 340 is determined. The sum of the transmission time of the first data 401 recorded by the main device 200 notified by the third data 403 and the transmission time of the first data 401 corrected by the main device 200, and the main device notified by the fourth data 404 are subtracted. The total of the reception time of the second data 402 of the 200 record and the reception time of the second data 402 corrected by the main device 200 is subtracted from the transmission time of the second data 402 recorded by the recording unit 330 and the second data 402 corrected by the correction unit 340. The sum of the total values of the moments, the value divided by 4 becomes a one-way delay. Then, the reception time of the first data 401 recorded by the recording unit 330 and the reception time of the first data 401 corrected by the correction unit 340 are subtracted from the transmission time of the first data 401 recorded by the host device 200 and the correction by the host device 200. The total value of the data 401 transmission time is divided by 2, and the total time of the reception time of the second data 402 recorded by the host device 200 and the second data 402 reception time corrected by the host device 200 is subtracted from the recording unit 330. The value of the second data 402 transmission time and the total of the transmission time of the second data 402 corrected by the correction unit 340 is divided by two, and the value obtained by subtracting the one-way delay becomes the offset 405.

That is, the offset 405 is T_offset, according to the record of the host device 200. The transmission time of the first data 401 recorded by the recording unit 230 is T_m1, the correction value of T_m1 is T_m1', and the reception time of the first data 401 recorded by the recording unit 330 of the time synchronization device 300 is T_s1, and the correction value of T_s1 is T_s1'. The transmission time of the second data 402 recorded by the recording unit 330 of the time synchronization device 300 is T_s2, the correction value of T_s2 is T_s2', and the reception time of the second data 402 recorded by the recording unit 230 of the main device 200 is T_m2 and T_m2. When the correction value is T_m2', T_offset=((T_s1+T_s1')-(T_m1+T_m1'))/2-(((T_s1+T_s1')-(T_m1+T_m1'))+((T_m2+T_m2') -(T_s2+T_s2')))/4=(((T_s1+T_s1')-(T_m1+T_m1')-((T_m2+T_m2')-(T_s2+T_s2')))/4, or T_offset =((T_m2+T_m2')-(T_s2+T_s2'))/2-(((T_s1+T_s1')-(T_m1+T_m1'))+((T_m2+T_m2')-(T_s2+T_s2') )) /4 = (((T_s1 + T_s1') - (T_m1 + T_m1') - ((T_m2 + T_m2') - (T_s2 + T_s2'))) / 4. In step S31, such calculation can be used The equation can be used to find the offset 405.

Further, the reception time of the first data 401 corrected by the correction unit 340 is subtracted from the value of the transmission time of the first data 401 notified by the third data 403, and the reception time of the second data 402 notified by the fourth data 404 is subtracted. The value obtained by dividing the total value of the transmission time of the second data 402 corrected by the correction unit 340 by 2 is regarded as a one-way delay. In this case, the value of the transmission time of the first data 401 notified by the third data 403 and the second data 402 notified by the fourth material 404 are subtracted from the reception time of the first data 401 corrected by the correction unit 340. The value obtained by subtracting the value of the one-way delay from the reception time minus the value of the transmission time of the second data 402 corrected by the correction unit 340 becomes the offset 405.

That is, in step S31, use T_offset=(T_s1'-T_m1')-((T_s1'-T_m1')+(T_m2'-T_s2'))/2=((T_s1'-T_m1')-(T_m2'-T_s2'))/2, Or T_offset=(T_m2'-T_s2')-((T_s1'-T_m1')+(T_m2'-T_s2'))/2=-((T_s1'-T_m1')-(T_m2'-T_s2')) The calculation formula of /2 can also find the offset 405.

An example of mounting the main device 200 and the time synchronization device 300 will be described with reference to Fig. 6 .

The functions of the receiving unit 310 and the transmitting unit 320 of the time synchronization device 300 are installed in the PHY 302 and the MAC 303 (Media‧Access‧ Control; Media Access Controller). The PHY 302 and the MAC 303 are hardware built in the time synchronization device 300. Specifically, the PHY 302 is a wafer that performs physical layer processing of the OSI reference model, and the MAC 303 is a wafer that performs data link layer processing of the OSI reference model. Moreover, the PHY 302 and the MAC 303 may be integrated on the same chip.

Similarly, the functions of the transmitting unit 210 and the receiving unit 220 of the master device 200 are also installed in the PHY 202 and the MAC 203. The PHY 202 is a chip that performs physical layer processing, and the MAC 203 is a wafer that performs data link layer processing.

The function of the recording unit 330 of the time synchronization device 300 is installed in the MAC driver 304. The MAC driver 304 is a software mounted on the time synchronization device 300. Specifically, the MAC driver 304 uses the intermediate software utilized by the OS 305 in order to control and operate the MAC 303. The MAC driver 304 has a soft time stamp function that generates a time stamp using the slave clock 301.

Similarly, the function of the recording unit 230 of the main apparatus 200 is also installed in the MAC driver 204. The MAC driver 204 is an intermediate software that is utilized by the OS 205 in order to control and operate the MAC 203. The MAC driver 204 has a soft time stamp function that generates a time stamp using the master clock 201.

The functions of the correction unit 340 and the synchronization unit 350 of the time synchronization device 300 are installed in the time synchronization application 306. The time synchronization application 306 is a software installed in the time synchronization device 300. Specifically, the time synchronization application 306 is an application that operates on the OS 305 together with other applications 307. The time synchronization application 306 manages a correction table 308 for correcting fluctuations in time stamps generated by the MAC driver 304.

Similarly, the function of the correcting unit 240 of the main device 200 is installed in the time synchronization application 206. The time synchronization application 206 is an application that operates on the OS 205 together with other applications 207. The time synchronization application 206 manages the correction table 208 used to correct the fluctuations in the time stamps generated by the MAC driver 204.

The master device 200 that transmits the time and the OS of the time synchronization device 300 that synchronizes the time have the same hierarchical structure for the time synchronization. The hierarchy is configured as: an application layer corresponding to the OS 205, 305 and the time synchronization applications 206, 306; a data link layer corresponding to the MCA drivers 204, 304 and the MACs 203, 303; and a 3-layer structure corresponding to the physical layers of the PHYs 202, 302 . As described above, in the time synchronization protocol of the present embodiment, the data link layer is directly accessed from the application layer without the transmission layer and the network layer of the OSI reference model.

The operation of the master device 200 and the time synchronization device 300 illustrated in Fig. 6 will be described with reference to Fig. 7 .

In the step S41 in which the main device 200 transmits the Sync message as the synchronization frame, the time synchronization application 206 generates a synchronization frame of the Sync message. The time synchronization application 206 does not store the time in the synchronization frame. When the OS 205 detects that the synchronization frame is generated by the time synchronization application 206, The priority interrupt is interrupted, and the synchronization frame is input to the MAC driver 204 earlier than other frames. The MAC driver 204 records the transmission time T_m1 of the synchronization frame by generating a software time stamp at the time of inputting the synchronization frame. Thereafter, the MAC driver 204 inputs the sync frame to the MAC 203. The MAC 203 transmits a sync frame from the PHY 202. The MAC driver 204 feeds back the recorded transmission time T_m1 to the time synchronization application 206. The time synchronization application 206 stores the transfer time T_m1 fed back from the MAC driver 204 in the forefront of the first row blank column of the correction table 208. The time synchronization application 206 generates random numbers based on the normal distribution, and stores the generated random numbers in the same column of the second row of the correction table 208. The time synchronization application 206 corrects the fluctuation of the transmission time T_m1 by subtracting the random number stored in the second line of the correction table 208 from the transmission time T_m1 stored in the first line of the correction table 208. The time synchronization application 206 stores the corrected transmission time T_m1' in the same column of the third row of the correction table 208. Further, the transmission time T_m1 may be corrected by subtracting the random number from the transmission time T_m1 by another method such as adding a random number at the transmission time T_m1. Further, which row of the correction table 208 is stored in the transmission time T_m1, the random number, and the corrected transmission time T_m1' can be appropriately changed.

In step S51 in which the time synchronization device 300 receives the Sync message as the synchronization frame, the PHY 302 receives the synchronization frame from the main device 200. The PHY 302 inputs the received sync frame to the MAC 303. The MAC driver 304 generates a software time stamp by detecting the timing at which the synchronization frame is input to the MAC 303, and records the reception timing T_s1 of the synchronization frame. Thereafter, the MAC driver 304 immediately inputs the recorded reception time T_s1 to the time synchronization application 306. The time synchronization application 306 will receive the reception time T_s1 from the MAC driver 304. Stored in the forefront of the blank column in the first row of the correction table 308. The time synchronization application 306 generates random numbers based on the normal distribution, and stores the generated random numbers in the same column of the second row of the correction table 308. The time synchronization application 306 corrects the fluctuation of the reception time T_s1 by subtracting the random number stored in the second line of the correction table 308 from the reception time T_s1 stored in the first line of the correction table 308. The time synchronization application 306 stores the corrected reception time T_s1' in the same column of the third row of the correction table 308. Further, the reception time T_s1 may be corrected by subtracting the random number from the reception time T_s1 by another method such as adding a random number at the reception time T_s1. Further, which row of the correction table 308 is stored in the correction time T_s1, the random number, and the corrected reception time T_s1' can be appropriately changed.

In the step S42 in which the main device 200 transmits the Follow-Up message as the synchronization frame, the time synchronization application 206 generates a synchronization frame of the Follow-Up message. The time synchronization application 206 stores the corrections in the first row and the third row of the correction table 208 and the corrected transmission time T_m1, T_m1' in the synchronization frame storage before the correction of the last column and the corrected The transmission time T_m1, T_m1' is combined, that is, before the correction of the Sync message and the corrected transmission time T_m1, T_m1'. When the OS 205 detects that the synchronization frame is generated by the time synchronization application 206, the priority interrupt is activated, and the synchronization frame is input to the MAC driver 204 earlier than the other frames. The MAC driver 204 generates a software time stamp at the point of time when the sync frame is input. However, the MAC driver 204 detects that the sync frame is a Follow-Up message, and only stores the generated time stamp in the buffer or the like for a certain period of time without being fed back to the time synchronization application 206. Thereafter, the MAC driver 204 inputs the sync frame to the MAC 203. The MAC 203 transmits a sync frame from the PHY 202.

In step S52 in which the time synchronization device 300 receives the Follow-Up message as the synchronization frame, the PHY 302 receives the synchronization frame from the main device 200. The PHY 302 inputs the received sync frame to the MAC 303. The MAC driver 304 generates a software time stamp when it detects that the sync frame is input to the MAC 303. However, the MAC driver 304 detects that the sync frame is a Follow-Up message, and only stores the generated time stamp in the buffer or the like for a certain period of time without inputting to the time synchronization application 306. Thereafter, the MAC driver 304 inputs the sync frame to the time synchronization application 306 via the OS 305. The time synchronization application 306 detects that the synchronization frame input from the MAC 304 is a Follow-Up message, and extracts the pre-correction transmission time T_m1, T_m1' stored before the correction of the synchronization frame.

In step S53, in which the time synchronization device 300 transmits the Delya_Req message as the synchronization frame, the time synchronization application 306 generates a synchronization frame of the Delya_Req message. The time synchronization application 306 does not store the time in the synchronization frame. When the OS 305 detects that the synchronization frame is generated by the time synchronization application 306, the priority interrupt is activated, and the synchronization frame is input to the MAC driver 304 earlier than the other frames. The MAC driver 304 records the transmission time T_s2 of the synchronization frame by generating a software time stamp at the time of input of the synchronization frame. Thereafter, the MAC driver 304 inputs the sync frame to the MAC 303. The MAC 303 transmits a sync frame from the PHY 302. The MAC driver 304 feeds back the recorded transmission time T_s2 to the time synchronization application 306. The time synchronization application 306 stores the transfer time T_s2 fed back from the MAC driver 304 in the forefront of the blank column of the fourth row of the correction table 308. The time synchronization application 306 generates a random number according to the normal distribution, and stores the generated random number in the correction table 308. The same column on line 5. The time synchronization application 306 corrects the fluctuation of the transmission time T_s2 by subtracting the random number stored in the 5th line of the correction table 308 from the transmission time T_s2 stored in the 4th line of the correction table 308. The time synchronization application 306 stores the corrected transmission time T_s2' in the same column of the sixth row of the correction table 308. Further, the transmission time T_s2 may be corrected by subtracting the random number from the transmission time T_s2 by another method such as adding a random number at the transmission time T_s2. Further, which row of the correction table 308 is stored in the transmission time T_s2, the random number, and the corrected transmission time T_s2' can be appropriately changed.

In step S43 in which the main device 200 receives the Delya_Req message as the synchronization frame, the PHY 202 receives the synchronization frame from the time synchronization device 300. The PHY 202 inputs the received sync frame to the MAC 203. The MAC driver 204 records the reception time T-m2 of the synchronization frame by generating a software time stamp when detecting that the synchronization frame is input to the MAC 203. Thereafter, the MAC driver 204 immediately inputs the recorded reception time T-m2 to the time synchronization application 206. The time synchronization application 206 stores the reception time T-m2 input from the MAC driver 204 in the forefront of the blank column of the fourth row of the correction table 208. The time synchronization application 206 generates random numbers based on the normal distribution, and stores the generated random numbers in the same column of the fifth row of the correction table 208. The time synchronization application 206 corrects the fluctuation of the reception time T-m2 by subtracting the random number stored in the 5th line of the correction table 208 from the reception time T-m2 stored in the 4th line of the correction table 208. The time synchronization application 206 stores the corrected reception time T-m2' in the same column of the sixth row of the correction table 208. Further, the reception time T-m2 may be corrected by subtracting the random number from the reception time T-m2 by another method such as adding a random number at the reception time T-m2. Further, the reception time T-m2, the random number, and the corrected reception time T-m2' will be received. Which row of the correction table 208 is stored can be changed as appropriate.

In the step S44 in which the main device 200 transmits the Delay_Resp message as the synchronization frame, the time synchronization application 206 generates a synchronization frame of the Delay_Resp message. The time synchronization application 206 stores the corrections in the fourth row and the sixth row of the correction table 208 before the correction and the corrected transmission time T_m2, T_m2' are stored in the combination of the last column and the corrected The transmission time T_m2, T_m2' is combined, that is, before the correction of the Delya_Req message and the corrected transmission time T_m2, T_m2'. When detecting that the synchronization frame is generated by the time synchronization application 206, the OS 205 starts the priority interrupt, and inputs the synchronization frame to the MAC driver 204 earlier than the other frames. The MAC driver 204 generates a software time stamp at the point of time when the sync frame is input. However, the MAC driver 204 detects that the sync frame is a Delay_Resp message, and only stores the generated time stamp in the buffer or the like for a certain period of time without being fed back to the time synchronization application 206. Thereafter, the MAC driver 204 inputs the sync frame to the MAC 203. The MAC 203 transmits a sync frame from the PHY 202.

In step S54 in which the time synchronization device 300 receives the Delay_Resp message as the synchronization frame, the PHY 302 receives the synchronization frame from the main device 200. The PHY 302 inputs the received sync frame to the MAC 303. The MAC driver 304 generates a software time stamp when it detects that the sync frame is input to the MAC 303. However, the MAC driver 304 detects that the sync frame is a Delay_Resp message, and only stores the generated time stamp in the buffer or the like for a certain period of time without being input to the time synchronization application 306. Thereafter, the MAC driver 304 inputs the sync frame to the time synchronization application 306 via the OS 305. The time synchronization application 306 detects that the synchronization frame input from the MAC 304 is Delay_Resp. The message is retrieved before the correction of the sync frame and the corrected transmission time T_m2, T_m2'.

After the step S54, the time synchronization application 306 uses: before the correction of the 1st line and the 3rd line of the correction table 308 and the corrected transmission time T_s1, T_s1' by the step S51; the correction by the step S52 The pre- and corrected transmission time T_m1, T_m1'; stored in the fourth and sixth lines of the correction table 308 before the correction and the corrected reception time T_s2, T_s2'; and the step S54 is taken out in step S53; The offset 405 is calculated before the correction and the corrected reception time T_m2, T_m2'. As far as the calculation formula is concerned, as described above, although T_offset = (((T_s1 + T_s1') - (T_m1 + T_m1')) - ((T_m2 + T_m2') - (T_s2 + T_s2'))) / 4, or T_offset=-(((T_s1+T_s1')-(T_m1+T_m1'))-((T_m2+T_m2')-(T_s2+T_s2')))/4, but other calculation formulas can also be used .

Thereafter, the order of steps S41 to S44 and the order of step S51 to step S54 are repeatedly performed.

*** Effect Description***

In the present embodiment, since the timing of recording using the software clock is corrected, the time synchronization accuracy according to the time synchronization method of the software base mounting can be improved.

Embodiment 2.

The difference from the first embodiment will be mainly described with respect to the present embodiment.

An example of the configuration of the time synchronization system 100 according to the present embodiment will be described with reference to Fig. 8 .

In this example, the same tree-like network as the one shown in Figure 1 is used. Architecture.

In the first embodiment, the second time synchronization method 102 can be applied to time synchronization in all sub-networks. However, in the present embodiment, the first time synchronization mode 101 is applied to time synchronization in a part of the sub-networks. .

Therefore, among the PLCs 120 connected to the GM 110, a part of the PLCs 120 is also the terminal on the transmission side in the first time synchronization method 101, and corresponds to both the master device 200 and the time synchronization device 300. Further, the field device 130 connected to the part of the PLC 120 is the terminal on the receiving side in the first time synchronization mode 101, and corresponds to the time synchronization device 300.

The configuration and operation of the master device 200 and the time synchronization device 300 according to the present embodiment are the same as those in the first embodiment.

Embodiment 3.

The difference from the first embodiment will be mainly described with respect to the present embodiment.

An example of the configuration of the time synchronization system 100 according to the present embodiment will be described with reference to Fig. 9 .

In this case, some use a linear network architecture. Three PLCs 120 are connected in series in the GM110. Among the three lower PLC120s, at least one PLC120 or at least two field devices 130 are connected to form a tree-shaped subnetwork.

The time synchronization between the GM 110 and the PLC 120 connected in series with the GM 110 is suitable for the first time synchronization method 101. The time synchronization between the PLCs 120 connected in series with the GM 110 is also applied to the first time synchronization method 101.

Therefore, among the PLCs 120 connected in series with the GM110, The two PLCs 120 are also the terminals on the transmission side in the first time synchronization method 101, and correspond to both the master device 200 and the time synchronization device 300. In this way, the present embodiment is configured such that the host can be dispersed in the GM 110 and the two PLCs 120.

Further, among the PLCs 120 connected in series with the GM 110, the two intermediate PLCs 120 do not become the terminals on the transmission side in the first time synchronization method 101, but may simply transfer the synchronization frame between the GM 110 and the other PLCs 120. In this case, the two intermediate PLCs 120 correspond to only the time synchronization device 300. In this way, in the present embodiment, the host can be changed to the form of the GM 110.

The configuration and operation of the master device 200 and the time synchronization device 300 according to the present embodiment are the same as those in the first embodiment.

Hereinafter, a hardware configuration example of the time synchronization device 300 according to the embodiment of the present invention will be described with reference to FIG.

The time synchronization device 300 is a computer. The time synchronization device 300 is a hardware including a processor 901, an auxiliary memory device 902, a memory 903, a communication device 904, an input interface 905, and a display interface. The processor 901 is connected to other hardware through the signal line 910 to control these other hardware. The input interface 905 is connected to the input device 907. Display interface 906 is coupled to display 908.

The processor 901 is an IC (Integrated‧Circuit) that performs processing. The processor 901 is, for example, a CPU (Central‧Processing‧Unit; central processing unit), a DSP (Digital‧Signal‧Processor; digital signal processor), or a GPU (Graphics‧Processing‧Unit; graphics processor).

The auxiliary memory device 902 is a ROM (Read‧Only‧Memory; Record-only memory, flash memory, or HDD (Hard‧Disk‧Drive; hard disk drive) and other recording media.

The memory 903 is, for example, a RAM (Random ‧ Access ‧ Memory)

The communication device 904 includes a receiver 921 that receives data and a transmitter 922 that transmits data. The communication device 904 is, for example, a communication chip or an NIC (Network‧Interface‧Card; network interface card).

The input interface 905 is a port that is connected to the electric wire 911 of the input device 907. The input interface 905 is, for example, a USB (Universal‧Serial‧Bus) terminal.

Display interface 906 is a port that is connected to wire 912 of display 908. The display interface 906 is, for example, a USB terminal or an HDMI (trademark) (High‧Definition‧Multimedia‧Interface) terminal.

The input device 907 is, for example, a mouse, a touch pen, a keyboard, or a touch panel.

The display 908 is, for example, an LCD (Liquid‧Crystal® Display).

In the auxiliary storage device 902, a program for realizing the functions of the so-called "parts" of the receiving unit 310, the transmitting unit 320, the recording unit 330, the correcting unit 340, and the synchronizing unit 350 is stored. The program is loaded in the memory 903, read into the processor 901, and executed by the processor 901. In the auxiliary memory device 902, an OS is also memorized. At least a part of the OS is loaded in the memory 903, and the processor 901 executes a program for realizing the function of the "part" while executing the OS.

In FIG. 10, although one processor 901 is shown, the time synchronization device 300 may include a plurality of processors 901. Furthermore, the plurality of processors 901 cooperate to execute a program that realizes the function of the "part".

The information, data, signal value, or variable value indicating the processing result of the "part" is stored in the auxiliary memory device 902, the memory 903, or the resistor or cache memory in the processor 901.

It is also possible to provide "parts" using "circuitry". Alternatively, you can replace "part" with "circuit", "step", "order" or "processing". "Circuit" and "circuitry" include not only processor 901, but also logic IC, GA (Gate‧Array; gate array), ASIC (Application‧Specific‧Integrated‧Circuit), FPGA (Field) -Programmable‧Gate‧Array; the concept of so-called other types of processing circuits.

Further, the hardware configuration shown in Fig. 10 can also be applied to the main device 200 according to the present embodiment.

Although the embodiments of the present invention have been described above, these embodiments may be combined and implemented. Alternatively, one or more of the embodiments may be implemented in part. For example, in the description of the embodiments, the "part" may be used as the instructor, and any combination of a few may be employed. Further, the present invention is not limited to the embodiments, and various modifications can be made as necessary.

100‧‧‧Time synchronization system

101‧‧‧First Time Synchronization

102‧‧‧Second Time Synchronization Mode

110‧‧‧GM (main master)

120‧‧‧PLC (programmable logic controller)

130‧‧‧Field devices

Claims (15)

A time synchronization device includes: a receiving unit that receives first data from a master device having a master clock; and a transmitting unit that transmits the second data to the master device after receiving the first data according to the receiving unit; and the recording unit The first data reception time of the receiving unit and the second data transmission time of the transmission unit are recorded by using a slave clock of the software clock, and the correction unit corrects the first data reception time and the second time recorded by the recording unit. And a synchronization unit that transmits at least the first data transmission time of the master device notified by the master device, the first data reception time corrected by the correction unit, and the second data transmission corrected by the correction unit And calculating an offset of a deviation between a time of the master clock and the slave clock from the second data receiving time of the master device notified by the master device, wherein the receiving unit repeatedly receives the first one from the master device The data recording unit records the receiving unit each time the receiving unit receives the first data. At the first data reception time, the correction unit generates a random number every time the first data reception time is recorded by the recording unit, and calculates the first data reception time by the recording unit using the generated random number. In the correction value, when the offset is calculated, the correction value of the first data reception time calculated by the correction unit is used as the first data connection. Receive time. The time synchronization device according to claim 1, wherein the transmitting unit transmits the second material to the main device every time the receiving unit receives the first data, and the recording unit transmits the data according to the transmission. When the second data is transmitted, the second data transfer time of the transfer unit is recorded, and the correction unit generates a random number every time the second data transfer time is recorded by the recording unit, and uses the generated random number to calculate The correction unit records the correction value of the second data transmission time, and the synchronization unit calculates the correction value of the second data transmission time calculated by the correction unit as the second data transmission when calculating the offset. time. The time synchronization device according to claim 1, wherein the synchronization unit calculates the offset every time the receiving unit receives the first data, and stores the plurality of calculated values of the offset, and stores the plurality of stored values. The statistical processing of the calculated values adjusts the timing of the aforementioned slave clock in response to the result of the foregoing statistical processing. The time synchronization device of claim 3, wherein the synchronization unit uses an average of the plurality of stored calculation values as a result of the statistical processing to adjust a timing of the slave clock. The time synchronization device of claim 1, wherein the receiving unit receives, from the master device, third data for notifying the first data transmission time of the master device, and the third device for notifying the master device 2 The fourth data of the time of receipt of the data, The synchronization unit refers to the third data and the fourth data received by the receiving unit when calculating the offset. The time synchronization device according to the first aspect of the invention, wherein the synchronization unit reads the first data transmission time from the master device, the first data transmission time corrected by the master device, and the first record recorded by the recording unit. a data reception time, the first data reception time corrected by the correction unit, the second data transmission time recorded by the recording unit, the second data transmission time corrected by the correction unit, and the aforementioned recording by the master device. The offset is calculated by the second data reception time and the second data reception time corrected by the master device. The time synchronization device of claim 6, wherein the synchronization unit is integrated with the first data transmission time recorded by the master device and the first data transmission time corrected by the master device, and recorded by the recording unit. a difference between the first data reception time and the first data reception time corrected by the correction unit; and the second data transmission time recorded by the recording unit and the second data transmission corrected by the correction unit The offset is calculated by summing the time and the difference between the second data reception time recorded by the master device and the second data reception time corrected by the master device. A time synchronization device includes: a receiving unit that receives first data from a master device having a master clock; and a transmitting unit that transmits the second data to the master device after receiving the first data according to the receiving unit; and the recording unit Recording the front of the receiving unit using the slave clock of the software clock The first data reception time and the second data transmission time of the transmission unit; the correction unit corrects the first data reception time and the second data transmission time recorded by the recording unit; and the synchronization unit, at least from the main The first data transmission time of the master device notified by the device, the first data reception time corrected by the correction unit, the second data transmission time corrected by the correction unit, and the master device notified from the master device At the second data reception time, an offset of the time difference between the master clock and the slave clock is calculated, wherein the synchronization unit reads the first data transmission time from the master device and the first device correction by the master device a data transmission time, the first data reception time recorded by the recording unit, the first data reception time corrected by the correction unit, the second data transmission time recorded by the recording unit, and the correction according to the correction unit The second data transmission time, the second data reception time and the foregoing recorded by the master device The second main information reception time correction means, calculate the offset. The time synchronization device of claim 8, wherein the synchronization unit is integrated with the first data transmission time recorded by the master device and the first data transmission time corrected by the master device, and recorded by the recording unit. a difference between the first data reception time and the first data reception time corrected by the correction unit; and the second data transmission time recorded by the recording unit and the second data transmission corrected by the correction unit The sum of the time, and the aforementioned second data recorded by the aforementioned master device The offset is calculated by the difference between the time of collection and the second data reception time corrected by the master device. The time synchronization device of claim 8, wherein the receiving unit receives, from the master device, a third data for notifying the first data transmission time of the master device, and the third device for notifying the master device In the fourth data of the data reception time, the synchronization unit refers to the third data and the fourth data received by the receiving unit when calculating the offset. A time synchronization system, comprising: a time synchronization device, as described in any one of claims 1 to 10; and a master device recording the first data transmission time and the second data using a master clock of a software clock At the reception time, the first data transmission time and the second data reception time that have been recorded are corrected, and at least the corrected first data transmission time and the second data reception time are notified to the time synchronization device. The time synchronization system of claim 11, wherein the master device further notifies the time synchronization device that the recorded first data transmission time and the second data reception time are recorded. A time synchronization system includes: a receiving unit that receives first data from a master device having a master clock; and a transmitting unit that transmits the second data to the master device after receiving the first data according to the receiving unit; and the recording unit Recording the front of the receiving unit using the slave clock of the software clock The first data reception time and the second data transmission time of the transmission unit; the correction unit corrects the first data reception time and the second data transmission time recorded by the recording unit; and the synchronization unit at least from the main device Notifying the first data transmission time of the master device, the first data reception time corrected by the correction unit, the second data transmission time corrected by the correction unit, and the master device notified from the master device The second data receiving time calculates an offset of the time difference between the master clock and the slave clock; and the master device records the first data transmission time and the second data reception time using the main clock of the software clock, and corrects The recorded first data transmission time and the second data reception time are notified to the time synchronization device at least the corrected first data transmission time and the second data reception time, wherein the master device further The first data transmission time recorded and the second data reception time are notified to the same time Step device. A time synchronization method, in which a master device having a master clock transmits first data, and a time synchronization device having a slave clock of a software clock receives the first data, and the time synchronization device transmits the second data after receiving the first data, The master device receives the second data, and the master device notifies the first data transmission time and the second data reception time. The time synchronization device records the first data reception time and the second data transmission time using the slave clock, and corrects the recorded first data reception time and the second data transmission time, and at least the aforementioned notification from the master device The first data transmission time, the corrected first data reception time, the corrected second data transmission time, and the second data reception time notified by the master device, the time of the master clock and the slave clock are calculated. The offset is offset, and the first data is repeatedly received from the master device, and the first data receiving time is recorded every time the first data is received, and a random number is generated every time the first data receiving time is recorded, and the number of random numbers is used. The generated random number is calculated as a correction value for recording the first data reception time, and when the offset is calculated, the calculated correction value of the first data reception time is used as the first data reception time. A time synchronization method, in which a master device having a master clock transmits first data, and a time synchronization device having a slave clock of a software clock receives the first data, and the time synchronization device transmits the second data after receiving the first data, The master device receives the second data, and the master device notifies the first data transmission time and the second data reception time, and the time synchronization device records the first data reception time and the second data transmission time using the slave clock. Correcting the recorded first data reception time and the second data transmission time, and receiving at least the first data transmission time notified from the master device and the corrected first data reception time At the time, the corrected second data transmission time, and the second data reception time notified by the master device, an offset of the time difference between the master clock and the slave clock is calculated, and the first record recorded from the master device The data transmission time, the first data transmission time corrected by the master device, the recorded first data reception time, the corrected first data reception time, the recorded second data transmission time, and the corrected second data transmission The offset is calculated at the time, the second data reception time recorded by the master device, and the second data reception time corrected by the master device.