WO2017068663A1

WO2017068663A1 - Communication device, communication method, and communication program

Info

Publication number: WO2017068663A1
Application number: PCT/JP2015/079696
Authority: WO
Inventors: 俊明富澤; 隆淺原
Original assignee: 三菱電機株式会社
Priority date: 2015-10-21
Filing date: 2015-10-21
Publication date: 2017-04-27

Abstract

A communication unit (3) transmits communication data to a time master device that transmits time information. A transmission control unit (19) prohibits communication data transmission from a communication unit (8) to the time master device at timing when the time master device transmits the time information.

Description

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMMUNICATION PROGRAM

The present invention relates to a technique for limiting the timing of transmitting communication data to a control device that transmits time information for time synchronization.

As a method of time synchronization, a method with feedback used in NTP (Network Time Protocol) or the like and a simple method without feedback disclosed in Patent Document 1 can be considered.
In the latter simple time synchronization method, the time master device transmits a radio frame such as a beacon that notifies the time held by the time master device to the surroundings, and the time slave device in a range in which communication with the time master device is possible The wireless frame transmitted from the time master device is received.
Then, the time slave device performs time synchronization by comparing the time notified by the radio frame with the time when the radio frame is received.
In such a method, a time difference is generated due to a difference between the frequency oscillator of the transmitter / receiver of the time master device and the frequency oscillator of the transmitter / receiver of the time slave device.
Furthermore, depending on the surrounding communication conditions, the time master device may have to wait for the transmission of the radio frame. When such a radio frame transmission wait occurs, a delay time is added. There is a problem in that it is impossible to accurately estimate a time lag caused by different oscillators.
As a technique for solving such a problem, there is a technique disclosed in Patent Document 2.

In Patent Document 2, a time master device transmits a data packet to which time information is attached, and a time slave device removes fluctuation errors caused by CSMA / CA (Carrier Sense Multiple Access / Collection Avidance), and the influence of the frequency oscillator. Estimated time lag due to.
In Patent Document 2, a time slave device calculates a time lag amount in time information.
The calculated deviation amount is used for determination of a filter time constant and filter processing.
In calculating the time lag, the time slave device firstly transmits the time interval tTD (k + 1) [0 ≦ k ≦ M−2] of the transmission source time information and the time interval tRD (k + 1) [0 ≦ 0 of the reception time information. k ≦ M−2] is calculated.
tTD (k + 1) = tT (k + 1) −tT (k), 0 ≦ k ≦ M−2 (1)
tRD (k + 1) = tR (k + 1) −tR (k), 0 ≦ k ≦ M−2 (2)
Next, the time slave device transmits the time interval tTD (k + 1) [0 ≦ k ≦ M−2] of the transmission source time information and the time interval tRD (k + 1) [0 ≦ k ≦ M−2] of the reception time information. ], The shift amount of the time interval of the reception time information with respect to the time interval of the transmission source time information is calculated as a time shift amount d (k + 1) [0 ≦ k ≦ M−2].
d (k + 1) = tRD (k + 1) −tTD (k + 1), 0 ≦ k ≦ M−2 (3)
Then, as a final processing result, the time slave device obtains a time lag amount (initial time lag amount) tR (0) -tT (0) of the reception time information with respect to the transmission source time information at the start of the filter processing, and finally A time lag amount (estimated time lag value) s (M−1) is obtained.
Then, the time slave device corrects the initial time lag amount tR (0) -tT (0) and the time lag estimated value s (M-1) as a time correction amount by subtracting from the reception time information of the current time slave device. By doing so, a time synchronized with the transmission source time information of the time master device is generated.
The initial time lag amount tR (0) -tT (0) reflects the result calculated when the time information is received only when the next time information is received, and thereafter, the time lag estimated value s (M− Only 1) is used.
In Patent Literature 2, by correcting such time lag, processing for synchronizing time information of the time slave device with time information of the time master device is realized.

JP 2009-111654 A JP 2014-96853 A

In the technique disclosed in Patent Document 2, when a traffic pattern that steadily affects a beacon on which time information is mounted is inserted, a fluctuation error due to CSMA / CA is inserted into the filter and is estimated by the time synchronization filter. There is a problem that the time lag of the frequency oscillator is increased.
For example, as shown in FIG. 22, the time information transmission cycle 13 transmitted from the time master device is long (for example, 100 ms) and the data transmission cycle 14 of communication data transmitted from the time slave device is short (for example, 1 ms). Suppose.
In this case, when communication data is transmitted from the time slave devices # 1 to #n in the time information transmission cycle 13, the transmission timing of the time information from the time master device is delayed.
Time information (without traffic) 15 indicates ideal transmission timing of time information, and time information (with traffic) 16 is time information delayed by CSMA / CA caused by transmission of communication data from the time slave device. The transmission timing is shown.
As described above, when communication data is transmitted from the time slave device at the transmission timing of the time information, the transmission of the time information is delayed by CSMA / CA, and an error occurs in the estimation of the time slave device. is there.

The main purpose of the present invention is to solve such a problem, and to make it possible to transmit time information without delay.

The communication device according to the present invention is
A communication unit that transmits communication data to a control device that transmits time information;
A transmission control unit that prohibits transmission of the communication data to the control device by the communication unit at a timing at which the control device transmits the time information.

According to the present invention, since the transmission of communication data to the control device at the timing when the control device transmits time information is prohibited, the control device can transmit time information without delay.

FIG. 3 is a diagram illustrating an example of a system configuration according to the first embodiment. FIG. 3 is a diagram showing an outline of an operation according to the first embodiment. FIG. 3 is a diagram illustrating a functional configuration example of a time slave device according to the first embodiment. FIG. 4 is a diagram showing an example of an operation sequence according to the first embodiment. FIG. 9 shows an example of an operation sequence according to the second embodiment. FIG. 10 is a diagram illustrating a functional configuration example of a time slave device according to a third embodiment. FIG. 10 shows an example of an operation sequence according to the third embodiment. FIG. 10 is a diagram illustrating a functional configuration example of a time slave device according to a fourth embodiment. FIG. 10 is a diagram showing an outline of an operation according to the fifth embodiment. FIG. 3 is a diagram illustrating a hardware configuration example of a time slave device according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a communication unit according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a communication data receiving unit according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a timing prediction unit according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a transmission control unit according to the first embodiment. FIG. 9 is a flowchart showing an operation example of a communication unit according to the second embodiment. FIG. 9 is a flowchart showing an operation example of a timing prediction unit according to the second embodiment. FIG. 9 is a flowchart showing an operation example of a transmission control unit according to the second embodiment. FIG. 9 is a flowchart showing an operation example of a transmission control unit according to the third embodiment. FIG. 9 is a flowchart showing an operation example of a time synchronization filter unit according to the fourth embodiment. FIG. 9 is a flowchart showing an operation example of a transmission control unit according to the fourth embodiment. FIG. 9 is a flowchart showing an operation example of a transmission control unit according to the fourth embodiment. The figure which shows the subject of a prior art.

Embodiment 1 FIG.
*** Explanation of configuration ***
FIG. 1 shows a system configuration example according to the present embodiment.
As shown in FIG. 1, the system according to the present embodiment includes a time master device 1 and a plurality of time slave devices 2.
The time master device 1 is a control device that transmits time information.
The time master device 1 transmits a radio frame including time information for notifying the time held by the time master device 1.
The time slave device 2 receives the radio frame transmitted from the time master device 1.
Then, the time slave device 2 performs time synchronization by comparing the time notified by the radio frame and the time when the radio frame is received.
The time synchronization method in the time slave device 2 may be the same as the method disclosed in Patent Document 2, for example.

FIG. 3 shows a functional configuration example of the time slave device 2 according to the present embodiment.
Each time slave device 2 shown in FIG. 1 has the functional configuration shown in FIG. 3 in common.
As shown in FIG. 3, the time slave device 2 according to the present embodiment includes a communication unit 8, a timing prediction unit 18, a transmission control unit 19, a communication data reception unit 20, a storage unit 21, a timer 22, and a slave time synchronization unit. 25.

Further, as shown in FIG. 10, the time slave device 2 includes hardware such as a processor 901, a storage device 902, a wireless communication I / F (Interface) 903, and a wired communication I / F 904.
The storage unit 21 is realized by the storage device 902.
The storage device 902 stores programs that realize the functions of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, and the slave time synchronization unit 25.
Then, the processor 901 executes these programs, and performs operations of a communication unit 8, a timing prediction unit 18, a transmission control unit 19, a communication data reception unit 20, a timer 22, and a slave time synchronization unit 25, which will be described later.
10 schematically illustrates a state in which the processor 901 is executing a program that realizes the functions of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, the timer 22, and the slave time synchronization unit 25. It represents.
The wireless communication I / F 903 is an interface for wireless communication with the time master device 1.
The wireless communication I / F 903 receives a wireless frame by wireless communication, and performs a demodulation process on the wireless frame. The communication unit 8 performs error correction processing on the radio frame after demodulation processing. If necessary, the communication unit 8 performs decapsulation processing of the radio frame.
Further, the communication unit 8 generates a radio frame by adding address information and an error correction code to the communication data in accordance with the communication protocol. The wireless communication I / F 903 performs modulation processing on the wireless frame generated by the communication unit 8 and transmits the wireless frame by wireless communication.
In the following, for simplicity of explanation, expressions such as “the communication unit 8 receives a radio frame” and “the communication unit 8 transmits a radio frame” are used. However, the reception of the radio frame and the transmission of the radio frame are used. Assume that the wireless communication I / F 903 performs the above-described operation.
The wired communication I / F 904 is an interface for wired communication.
The wired communication I / F 904 receives communication data by wired communication. The communication data receiving unit 20 performs error correction processing for communication data. Further, if necessary, the communication data receiving unit 20 performs communication data decapsulation processing.
In the following, for simplicity of explanation, the expression “communication data receiving unit 20 receives communication data” is used. However, in receiving communication data, wired communication I / F 904 performs the above-described operation. Shall.
Although FIG. 10 shows an example in which the timer 22 is realized by software, the timer 22 may be realized by hardware.

*** Explanation of operation ***
With reference to FIG. 2, an outline of the operation of time slave device 2 according to the present embodiment will be described.
In the present embodiment, the time slave device 2 predicts the time information transmission cycle 13 of the time master device 1 shown in FIG.
The time information transmission cycle 13 is an interval of time information transmission timing.
The time slave device 2 has a data transmission prohibition period 17 before and after the timing at which the time master device 1 transmits time information. During the data transmission prohibition period 17, the time slave device 2 transmits communication data from the time slave device 2. Do not do it.
That is, the time slave device 2 according to the present embodiment suspends transmission of communication data to the time master device 1 at the timing when the time master device 1 transmits time information, and the time master device 1 transmits time information. The communication data is transmitted to the time master device 1 at a timing other than the timing to be performed.
Thereby, the time master device 1 can transmit time information without delay.
The operation of the time slave device 2 corresponds to an example of a communication method and a communication program.

Next, details of the components of the time slave device 2 shown in FIG. 3 will be described.

The communication unit 8 receives a radio frame including time information from the time master device 1 via the radio communication I / F 903 and transmits a radio frame including communication data to the time master device 1.
The operation of the communication unit 8 corresponds to an example of communication processing.
The timing prediction unit 18 uses the timer 22 to predict the timing at which the time master device 1 transmits time information (hereinafter referred to as predicted transmission timing).
When the time set by the timing prediction unit 18 elapses, the timer 22 notifies the timing prediction unit 18 that the set time has elapsed.
The transmission control unit 19 sets the data transmission prohibition period 17 based on the predicted transmission timing predicted by the timing prediction unit 18, and the communication data to the time master device 1 by the communication unit 8 during the data transmission prohibition period 17. Prohibit sending.
More specifically, the transmission control unit 19 sets a period including a period from the predicted transmission timing until the time information is received by the communication unit 8 as the data transmission prohibition period 17.
The time master device 1 periodically transmits a radio frame including time information, and the transmission control unit 19 performs the time by the communication unit 8 at each timing at which the time master device 1 transmits a radio frame including time information. Transmission of radio frames to the master device 1 is prohibited.
The operation of the transmission control unit 19 corresponds to an example of a transmission control process.
The communication data receiving unit 20 receives communication data by wired communication via the wired communication I / F 904.
The accumulating unit 21 accumulates (buffers) the communication data received by the communication data receiving unit 20.
The transmission control unit 19 stores the communication data received by the communication data receiving unit 20 in the storage unit 21 during the data transmission prohibition period 17.
Then, the transmission control unit 19 causes the communication unit 8 to transmit the communication data stored in the storage unit 21 to the time master device 1 after the data transmission prohibition period 17 has elapsed.

In the slave time synchronization unit 25, the time synchronization information extraction unit 9 extracts time information from the radio frame received by the communication unit 8.
The time synchronization filter unit 10 compares the time information extracted by the time synchronization information extraction unit 9 with the internal time of the time slave device 2, and estimates the deviation of the internal time of the time slave device 2 with respect to the reference time of the time master device 1. The time correction amount is calculated.
The slave time setting unit 11 sets the time of the time slave device 2 using the time correction amount estimated by the time synchronization filter unit 10.
The slave internal time generation unit 12 generates the internal time of the time slave device 2 using the setting information from the slave time setting unit 11.

FIG. 4 shows a specific operation sequence example of the communication unit 8, the timing prediction unit 18, and the transmission control unit 19.

The timing prediction unit 18 sets a timer according to the time information transmission cycle 13, and regards the timing when the timer expires as the predicted transmission timing.
When the timer expires (S1), the timing prediction unit 18 outputs a communication data buffering start instruction to the transmission control unit 19 (S2).
The transmission control unit 19 starts buffering communication data in response to a buffering start instruction (S3).
That is, the transmission control unit 19 acquires the communication data received by the communication data receiving unit 20 from the communication data receiving unit 20 and buffers the communication data in the storage unit 21.
In addition, when the communication unit 8 receives a radio frame including time information from the time master device 1, the communication unit 8 notifies the timing prediction unit 18 that the time information has been received (S4).
The timing prediction unit 18 outputs a data transmission start instruction to the transmission control unit 19 (S5).
Further, the timing prediction unit 18 performs timer setting for predicting the transmission timing of the next time information (S6).
In response to the data transmission start instruction from the timing prediction unit 18, the transmission control unit 19 reads the buffering data from the storage unit 21, outputs the read buffering data to the communication unit 8, and ends the buffering (S7). .
The communication unit 8 starts transmission of buffering data (communication data) to the time master device 1.
From the predicted transmission timing (S1) to the reception of time information (S4) corresponds to the data transmission prohibition period 17 in FIG.

Next, an operation example of the communication unit 8 will be described with reference to FIG.
When receiving the radio frame (YES in S11), the communication unit 8 extracts time information from the radio frame and notifies the timing prediction unit 18 that the time information has been received (S12). The extracted time information is output to the slave time synchronization unit 25.
Next, when data is output from the transmission control unit 19 (YES in S13), the communication unit 8 adds a radio frame by adding address information and an error correction code to the data output from the transmission control unit 19. Generate and transmit the generated radio frame (S14).

Next, an operation example of the communication data receiving unit 20 will be described with reference to FIG.
When the communication data is received (YES in S21), the communication data receiving unit 20 outputs the communication data to the transmission control unit 19 after error correction processing (S22).

Next, an operation example of the timing prediction unit 18 will be described with reference to FIG.
First, the timing prediction unit 18 sets the timer 22 (S31).
Next, when the timer 22 has expired (YES in S32), that is, when notified from the timer 22, the timing prediction unit 18 outputs a buffering start instruction to the transmission control unit 19 (S33).
Next, when reception of time information is notified from the communication unit 8 (YES in S34), the timing control unit 18 outputs a data transmission start instruction to the transmission control unit 19 (S35).

Next, an operation example of the transmission control unit 19 will be described with reference to FIG.
When communication data is received by the communication data receiving unit 20 (YES in S41), the transmission control unit 19 acquires the communication data from the communication data receiving unit 20.
Next, when the buffering start instruction has already been output from the timing prediction unit 18 (YES in S42), the transmission control unit 19 performs buffering of communication data (S44).
On the other hand, when the buffering start instruction is not output (NO in S42), the transmission control unit 19 outputs the communication data to the communication unit 8.
Next, when a data transmission start instruction is output from the timing prediction unit 18 (YES in S45), the transmission control unit 19 reads buffering data from the storage unit 21 (S46).
Then, the transmission control unit 19 outputs the buffering data read from the storage unit 21 to the communication unit 8 (S47).

In FIG. 4, the communication unit 8 notifies the timing prediction unit 18 that the time information has been received after the data transmission prohibition period, and the timing prediction unit 18 outputs a data transmission start instruction to the transmission control unit 19 for transmission. The controller 19 has stopped buffering.
Instead, when the communication unit 8 receives the time information, it notifies the timing prediction unit 18 that the time information has been received even during the data transmission prohibition period, and the transmission control unit 19 buffers the data transmission prohibition period. The ring may be stopped and the communication unit 8 may transmit buffering data.
That is, when the time information is received by the communication unit 8 during the data transmission prohibition period, the transmission control unit 19 transmits the communication data to the time master device 1 by the communication unit 8 even during the data transmission prohibition period. Transmission may be permitted.

*** Explanation of the effect of the embodiment ***
As described above, the time slave device 2 according to the first embodiment prohibits transmission of communication data to the time master device 1 at the timing when the time master device 1 transmits time information. Time information can be transmitted.
Since no fluctuation error occurs in the transmission of time information, the time synchronization filter can be operated normally.

Embodiment 2. FIG.
In the first embodiment, as shown in FIG. 4, when the communication unit 8 receives time information from the time master device 1, the transmission control unit 19 stops buffering and outputs buffering data to the communication unit 8. To do.
In the present embodiment, an example will be described in which the transmission control unit 19 stops buffering and outputs buffering data to the communication unit 8 asynchronously with reception of time information by the communication unit 8.
The functional configuration of the time master device 1 and the functional configuration of the time slave device 2 according to the present embodiment are the same as those described in the first embodiment.
In the present embodiment, the data size of each communication data is the same, and the communication data receiving unit 20 receives the communication data at a reception rate within a certain range.
In the following, differences from the first embodiment will be mainly described. Matters not described below are the same as those in the first embodiment.

FIG. 5 shows an example of an operation sequence of the time slave device 2 according to the present embodiment.
Similar to the first embodiment, the timing prediction unit 18 sets a timer and sets the timing when the timer expires as the predicted transmission timing.
When the timer expires, the timing prediction unit 18 outputs a communication data buffering start instruction to the transmission control unit 19 (S2) and sets the timer (S8).
The transmission control unit 19 starts buffering communication data in response to a buffering start instruction (S3).
The transmission control unit 19 stores a transmission threshold that is a predetermined value, and determines whether or not the data amount of the buffering data is equal to or larger than the transmission threshold (S9).
The transmission control unit 19 continues buffering until the amount of buffered data reaches the transmission threshold.
When the data amount of the buffering data reaches the transmission threshold, the transmission control unit 19 reads the buffering data from the storage unit 21, outputs the read buffering data to the communication unit 8, and ends the buffering (S7). ).
In the present embodiment, the period from the predicted transmission timing (S8) until the data amount of the buffering data reaches the transmission threshold (YES in S9) corresponds to the data transmission prohibition period 17 in FIG.

Next, an operation example of the communication unit 8 will be described with reference to FIG.
When data is output from the transmission control unit 19 (YES in S13), the communication unit 8 generates a radio frame by adding address information and an error correction code to the data output from the transmission control unit 19, The generated radio frame is transmitted (S14).

Next, an operation example of the timing prediction unit 18 will be described with reference to FIG.
First, the timing prediction unit 18 sets the timer 22 (S31).
Next, when the timer 22 has expired (YES in S32), that is, when notified from the timer 22, the timing prediction unit 18 outputs a buffering start instruction to the transmission control unit 19 (S33).

Next, an operation example of the transmission control unit 19 will be described with reference to FIG.
When communication data is received by the communication data receiving unit 20 (YES in S41), the transmission control unit 19 acquires the communication data from the communication data receiving unit 20.
Next, when the buffering start instruction has already been output from the timing prediction unit 18 (YES in S42), the transmission control unit 19 performs buffering of communication data (S44).
On the other hand, when the buffering start instruction is not output (NO in S42), the transmission control unit 19 outputs the communication data to the communication unit 8.
Next, when the data amount of the buffering data is equal to or larger than the transmission threshold (YES in S48), the transmission control unit 19 reads the buffering data from the storage unit 21 (S46).
Then, the transmission control unit 19 outputs the buffering data read from the storage unit 21 to the communication unit 8 (S47).

In the present embodiment, even when the buffering data is transmitted to the time master device 1 when the data amount of the buffering data reaches the transmission threshold, the transmission timing of the buffering data is the transmission timing of the time information of the time master device 1. It is necessary not to overlap.
For this reason, the following (1), (2-1), and (2-2) are conceivable as transmission threshold values in the present embodiment.
(1) A transmission threshold may be considered such that the time from the start of buffering until the amount of buffered data reaches the transmission threshold slightly exceeds the time information transmission cycle 13.
By multiplying the data size of the communication data by the communication data reception rate of the communication data receiving unit 20, an approximate time from the start of buffering until the data amount of the buffering data reaches the transmission threshold is obtained. A transmission threshold that slightly exceeds the information transmission period 13 can be considered.
(2-1) A transmission threshold may be considered such that the time from the start of buffering until the amount of buffered data reaches the transmission threshold is an integral multiple of the time information transmission period 13.
(2-2) Transmission threshold value such that the time from the start of buffering until the amount of buffered data reaches the transmission threshold value is equivalent to the remainder obtained by dividing the time information transmission period 13 by the number of time slave devices 2 Can be considered.
It is also possible to set a different transmission threshold value for each time slave device 2.

As described above, in the present embodiment, the transmission control unit 19 sets a period from the predicted transmission timing until the accumulated amount of communication data in the accumulating unit 21 reaches the transmission threshold value which is a predetermined value as the data transmission prohibition period.
Then, the transmission control unit 19 causes the storage unit 21 to store the communication data received by the communication data receiving unit 20 during the data transmission prohibition period.
After the data transmission prohibition period has elapsed, the transmission control unit 19 causes the communication unit 8 to transmit the communication data stored in the storage unit 21 to the time master device 1.

Embodiment 3 FIG.
In the present embodiment, a time slave device 2 in which the timing prediction unit 18 shown in FIG. 3 is omitted will be described.

FIG. 6 shows a functional configuration example of the time slave device 2 according to the present embodiment.
In FIG. 6, the timing prediction unit 18 shown in FIG. 3 is omitted.
Each component shown in FIG. 6 is the same as the component given the same reference numeral shown in FIG.
In the present embodiment, the data size of each communication data is the same, and the communication data receiving unit 20 receives the communication data at a reception rate within a certain range.
The functional configuration of the time master device 1 according to the present embodiment is the same as that described in the first embodiment.
In the following, differences from the first embodiment will be mainly described. Matters not described below are the same as those in the first embodiment.

FIG. 7 shows an example of an operation sequence of the time slave device 2 according to the present embodiment.
Also in the present embodiment, the communication data receiving unit 20 receives the communication data (S11) and transfers the received communication data to the transmission control unit 19.
The transmission control unit 19 buffers the communication data in the storage unit 21 (S3).
The transmission control unit 19 stores a transmission threshold that is a predetermined value, and determines whether or not the data amount of the buffering data is equal to or larger than the transmission threshold (S9).
The transmission control unit 19 continues buffering until the amount of buffered data reaches the transmission threshold.
When the data amount of the buffering data reaches the transmission threshold, the transmission control unit 19 reads the buffering data from the storage unit 21, outputs the read buffering data to the communication unit 8, and ends the buffering (S7). ).
In this embodiment, it is conceivable to use the transmission threshold values (2-1) and (2-2) described in the second embodiment.
That is, even in the present embodiment, even when the buffering data is transmitted to the time master device 1 when the data amount of the buffering data reaches the transmission threshold, the transmission timing of the buffering data is the time information of the time master device 1. Does not overlap with transmission timing.

Next, an operation example of the transmission control unit 19 will be described with reference to FIG.
When communication data is received by the communication data receiving unit 20 (YES in S41), the transmission control unit 19 acquires the communication data from the communication data receiving unit 20.
Next, the transmission control unit 19 performs buffering of communication data (S44).
Next, when the data amount of the buffering data is equal to or larger than the transmission threshold (YES in S48), the transmission control unit 19 reads the buffering data from the storage unit 21 (S46).
Then, the transmission control unit 19 outputs the buffering data read from the storage unit 21 to the communication unit 8 (S47).

As described above, in the present embodiment, the transmission control unit 19 uses the accumulated amount of communication data in the accumulating unit 21 when the communication data received by the communication data receiving unit 20 is accumulated in the accumulating unit 21 as the transmission threshold. The transmission threshold value that does not overlap with the timing at which the time master device 1 transmits time information is stored.
Then, the transmission control unit 19 causes the storage unit 21 to store the communication data received by the communication data receiving unit 20, and when the storage amount of the communication data in the storage unit 21 reaches the transmission threshold value, the communication unit 8, the communication data stored in the storage unit 21 is transmitted to the time master device 1.

Embodiment 4 FIG.
FIG. 8 shows a functional configuration example of the time slave device 2 according to the present embodiment.
Each component shown in FIG. 8 is the same as the component given the same reference numeral shown in FIG.
In the present embodiment, the time synchronization filter unit 10 corresponds to an example of a time analysis unit, and uses the reception time of the time information by the communication unit 8 and the time notified by the time information received by the communication unit 8. Perform analysis.
Then, the time synchronization filter unit 10 outputs to the transmission control unit 19 a value that is an analysis result and is used for calculation of variance of the time lag amount.
In the following, differences from the first embodiment will be mainly described. Matters not described below are the same as those in the first embodiment.

In the present embodiment, in the initial state, the transmission control unit 19 does not limit the transmission timing of communication data, and the time synchronization filter unit 10 performs the above-described equations (1) to (3) as in Patent Document 2. Calculation based on
Then, the time synchronization filter unit 10 transmits the value of tTD (k + 1) shown in Equation (1), the value of tRD (k + 1) shown in Equation (2), and the value of d (k + 1) shown in Equation (3). Output to the control unit 19.
When the value output from the time synchronization filter unit 10 matches a predetermined condition, the transmission control unit 19 communicates with the time master device 1 by the communication unit 8 at a timing when the time master device 1 transmits time information. Prohibit data transmission.
That is, the transmission control unit 19 calculates the variance of the value output from the time synchronization filter unit 10 (dispersion of the time shift amount due to the influence of the frequency oscillator), and when the calculated variance exceeds a certain value, FIG. As shown, the timing at which the time master device 1 transmits time information is determined to be delayed by CSMA / CA, and the transmission timing of communication data is limited by the method shown in the first embodiment, for example.

The transmission control unit 19 calculates the variance of the time lag amount by the following calculation using the values of the equations (1) to (3).
Dispersion of time lag amount = (Σ (d (k + 1) −u) ² ) / (M−2) (4)
However, u is an average value of the time lag amount. When the calculated dispersion value of the time lapse amount exceeds a certain value, the transmission control unit 19 determines the transmission timing of communication data by the method shown in the first embodiment, for example. Start restriction.

Next, an operation example of the time synchronization filter unit 10 will be described with reference to FIG.
First, the time synchronization filter unit 10 calculates the value of tTD (k + 1) (S61).
Next, the time synchronization filter unit 10 calculates the value of tRD (k + 1) (S62).
Next, the time synchronization filter unit 10 calculates the value of d (k + 1) (S63).
Then, the time synchronization filter unit 10 outputs the value of tTD (k + 1), the value of tRD (k + 1), and the value of d (k + 1) to the transmission control unit 19 (S64).

Next, an operation example of the transmission control unit 19 will be described with reference to FIGS.
When communication data is received by the communication data receiving unit 20 (YES in S41), the transmission control unit 19 acquires the communication data from the communication data receiving unit 20.
Next, the transmission control unit 19 determines whether or not the value of tTD (k + 1), the value of tRD (k + 1), and the value of d (k + 1) are acquired from the time synchronization filter unit 10 (S51).
If these values have not been acquired (NO in S51), the transmission control unit 19 performs the process of step S43.
On the other hand, when these values are acquired (YES in S51), the transmission control unit 19 uses these values to determine whether or not to prohibit transmission of communication data as described above ( S52).
When the transmission of communication data is prohibited, the transmission control unit 19 performs the process of step S44, and when the transmission of communication data is not prohibited, the transmission control unit 19 performs the process of step S43.
In step S <b> 43, the transmission control unit 19 outputs communication data to the communication unit 8.
In step S44, the transmission control unit 19 buffers communication data.
Next, when the data amount of the buffering data is equal to or larger than the transmission threshold (YES in S48), the transmission control unit 19 reads the buffering data from the storage unit 21 (S46).
Then, the transmission control unit 19 outputs the buffering data read from the storage unit 21 to the communication unit 8 (S47).
When the data amount of the buffering data is less than the transmission threshold (NO in S48), the operation after step S44 is repeated every time communication data is received (YES in S41).

Embodiment 5 FIG.
When the data transmission prohibition period 17 is provided in the plurality of time slave devices 2 by the method shown in the first embodiment, communication data can be transmitted simultaneously from the plurality of time slave devices 2 after the data transmission prohibition period 17 has elapsed. There is sex.
In the present embodiment, an example will be described in which a different data transmission prohibition period 17 is set for each time slave device 2 in order to avoid simultaneous transmission of communication data from the plurality of time slave devices 2.
In the following, differences from the first embodiment will be mainly described. Matters not described below are the same as those in the first embodiment.

FIG. 9 shows an operation example of the time slave device 2 according to the fifth embodiment.
In the present embodiment, the timing at which communication data is transmitted from a plurality of time slave devices 2 is dispersed by changing the length of the data transmission prohibition period 17 for each time slave device 2.
In this Embodiment, the transmission control part 19 of each time slave apparatus 2 determines the length of a data transmission prohibition period using a random number.
For example, the transmission control unit 19 of each time slave device 2 sets the length of the data transmission prohibited period with a random number using time information as a seed.
Further, the transmission control unit 19 of each time slave device 2 may use a random number with the number of time slave devices 2 as an upper limit.
In this case, the time master device 1 notifies the time slave devices 2 of the number of time slave devices 2.

As mentioned above, although embodiment of this invention was described, you may implement in combination of 2 or more among these embodiment.
Alternatively, one of these embodiments may be partially implemented.
Alternatively, two or more of these embodiments may be partially combined.
In addition, this invention is not limited to these embodiment, A various change is possible as needed.
*** Explanation of hardware configuration ***
Finally, a supplementary description of the hardware configuration of the time slave device 2 will be given.
The time slave device 2 is a computer.
A processor 901 illustrated in FIG. 10 has an IC (Integrated) that performs processing.
Circuit).
The processor 901 is a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or the like.
The storage device 902 illustrated in FIG. 10 is a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an HDD (Hard Disk Drive), or the like.
The wireless communication I / F 903 and the wired communication I / F 904 illustrated in FIG. 10 include a receiver that receives data and a transmitter that transmits data.
The wireless communication I / F 903 and the wired communication I / F 904 are, for example, a communication chip or a NIC (Network Interface Card).

The storage device 902 also stores an OS (Operating System).
Then, at least a part of the OS is executed by the processor 901.
The processor 901 executes a program that realizes the functions of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, the timer 22, and the slave time synchronization unit 25 while executing at least a part of the OS. .
Although one processor is illustrated in FIG. 10, the time slave device 2 may include a plurality of processors.
In addition, information, data, signal values, and variable values indicating processing results of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, the timer 22, and the slave time synchronization unit 25 are stored in the storage device 902. Or stored in a register or cache memory in the processor 901.
The programs for realizing the functions of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, the timer 22, and the slave time synchronization unit 25 are a magnetic disk, a flexible disk, an optical disk, a compact disk, and a Blu-ray. (Registered trademark) It may be stored in a portable storage medium such as a disk or DVD.

Further, the means for realizing the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, the timer 22, and the slave time synchronization unit 25 may be a “processing circuitry” or a “circuit”. It may be read as “process” or “procedure” or “processing”.
The “processing circuit” or “circuit” is not only the processor 901 but also other types of processing circuits such as a logic IC or GA (Gate Array) or ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). Is a concept that also includes
In addition, “to part” of the communication unit 8, the timing prediction unit 18, the transmission control unit 19, the communication data reception unit 20, and the slave time synchronization unit 25 may be read as “process”, “procedure”, or “processing”.

1 time master device, 2 time slave device, 3 reference time information signal, 4 reference time receiving unit, 5 master time setting unit, 6 master internal time generation unit, 7 time information insertion unit, 8 communication unit, 9 time synchronization information extraction Unit, 10 time synchronization filter unit, 11 slave time setting unit, 12 slave internal time generation unit, 13 time information transmission cycle, 14 data transmission cycle, 15 time information (without traffic), 16 time information (with traffic), 17 data Transmission prohibition period, 18 timing prediction unit, 19 transmission control unit, 20 communication data reception unit, 21 storage unit, 22 timer, 24 master time synchronization unit, 25 slave time synchronization unit, 200 time slave device.

Claims

A communication unit that transmits communication data to a control device that transmits time information;
A communication apparatus comprising: a transmission control unit that prohibits transmission of the communication data to the control device by the communication unit at a timing at which the control device transmits the time information.
The communication device further includes:
A timing prediction unit for predicting a timing at which the control device transmits the time information;
The transmission control unit
The data transmission prohibition period is set based on the predicted transmission timing predicted by the timing prediction unit, and the communication unit prohibits transmission of the communication data to the control device during the data transmission prohibition period. The communication apparatus according to 1.
The communication unit is
Receiving the time information transmitted from the control device;
The transmission control unit
The communication apparatus according to claim 2, wherein a period including a period from the predicted transmission timing until the time information is received by the communication unit is set as the data transmission prohibition period.
The communication device further includes:
A communication data receiving unit for receiving the communication data;
A storage unit for storing the communication data;
The transmission control unit
During the data transmission prohibition period, the storage unit stores the communication data received by the communication data reception unit, and after the data transmission prohibition period has elapsed, the communication unit stores the communication data in the storage unit. The communication device according to claim 3, wherein the communication data is transmitted to the control device.
The transmission control unit
When the time information is received by the communication unit during the data transmission prohibition period, transmission of the communication data to the control device by the communication unit is permitted even during the data transmission prohibition period. Item 3. The communication device according to Item 2.
The communication device further includes:
A communication data receiving unit for receiving the communication data;
A storage unit for storing the communication data;
The transmission control unit
A period from the predicted transmission timing until the amount of communication data stored in the storage unit reaches a threshold is set as the data transmission prohibition period,
During the data transmission prohibition period, the storage unit stores the communication data received by the communication data reception unit, and after the data transmission prohibition period has elapsed, the communication unit stores the communication data in the storage unit. The communication device according to claim 2, wherein the communication data is transmitted to the control device.
The communication device further includes:
A communication data receiving unit for receiving the communication data at a certain range of reception rates;
A storage unit for storing the communication data;
The transmission control unit
When the communication data received by the communication data receiving unit is stored in the storage unit, the timing at which the storage amount of the communication data in the storage unit reaches a threshold is the timing at which the control device transmits the time information Memorize the threshold value that does not overlap with
The storage unit stores the communication data received by the communication data receiving unit, and when the storage amount of the communication data in the storage unit reaches the threshold value, the storage unit stores the communication data. The communication device according to claim 1, wherein the communication data stored in the communication device is transmitted to the control device.
The communication device further includes:
A time analysis unit that performs analysis using the reception time of the time information by the communication unit and the time notified by the time information received by the communication unit;
The transmission control unit
The transmission of the communication data to the control device by the communication unit at a timing when the control device transmits the time information when the analysis result by the time analysis unit matches a predetermined condition. The communication apparatus as described in.
The transmission control unit
The communication apparatus according to claim 2, wherein a length of the data transmission prohibition period is determined using a random number.
The control device includes:
Send the time information periodically,
The transmission control unit
The communication device according to claim 1, wherein transmission of the communication data to the control device by the communication unit is prohibited at each timing at which the control device transmits the time information.
A communication device that transmits communication data to a control device that transmits time information.
At the timing when the control device transmits the time information, transmission of communication data to the control device is suspended, and the communication data is transmitted to the control device at a timing other than the timing at which the control device transmits the time information. Communication method.
A communication process for transmitting communication data to a control device for transmitting time information;
A communication program for causing a computer to execute a transmission control process for prohibiting transmission of the communication data to the control apparatus by the communication process at a timing at which the control apparatus transmits the time information.