JP2009130519A - Synchronization system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish synchronization even in logical ring networks of all connection forms such as asymmetrical double ring type network, etc. <P>SOLUTION: A time master device (M) transmits measurement information for measuring a communication time. Moreover, the time master device (M) measures the time from transmission of the measurement information until reception thereof again through a network. Respective time slave devices (Sx) measure the time from receiving the measurement information until receiving again. Respective branching devices (Cx) measure the time from receiving the measurement information until receiving again. The respective time slave devices (Sx) calculate the delay time based on the time measured by the respective devices. Moreover, the respective time slave devices (Sx) calculate the time after the delay time from the time at which the timing information of the same time calculation is received from the master time device (M) as the synchronization time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to, for example, a synchronization technique for synchronizing processing timings of devices provided in a network. In particular, the present invention relates to a synchronization technique of, for example, a double ring network.

A conventional network synchronization apparatus related to a ring network realizes synchronization by transmitting a frame in both directions of a double ring, measuring the time difference, and correcting it.
JP-A-6-69937

A conventional network synchronization apparatus for a ring network is a synchronization method that is effective only in the case of a symmetric double ring network. Here, the symmetric double ring network is a double ring network in which the devices provided in each of the two ring transmission lines, one transmission line and the other transmission line, are the same. It is. In other words, in a conventional network synchronization device for a ring network, synchronization is established in an asymmetric dual ring network in which the equipment provided on one transmission path and the other transmission path of the dual ring network are different. There is a problem that cannot be done.
An object of the present invention is to establish synchronization even in a logical ring network of any connection form.

The synchronization system according to the present invention includes, for example, an asymmetric double ring type comprising a main network of a double ring network, and a branch network that is branched from one ring of the main network and configured by bidirectional transmission lines. A time master device that transmits predetermined information, and a plurality of time slave devices that calculate a synchronization time for synchronizing processing timing with other devices based on the information transmitted by the time master device; , A synchronization system in a network including a plurality of devices with a branch device provided at a branch position between the main line network and the branch line network,
The time master device is
A master transmitter for transmitting measurement information for measuring communication time;
A master round trip time measuring unit that measures a master round trip time until the measurement information transmitted by the master transmission unit returns again around the network;
Each time slave device of the plurality of time slave devices is
A slave round trip time measuring unit that measures a slave round trip time from receiving the measurement information to receiving and transmitting the measurement information again,
The branching device is
A branch line round trip time measuring unit that measures a branch line round trip time from reception of the measurement information to reception and transmission of the measurement information from the branch network again;
A main line round trip time measuring unit that measures a main line round trip time from receiving the measurement information to receiving and transmitting the measurement information from the main line network again;
Each of the time slave devices is further
Master round trip time measured by the master round trip time measurement unit, slave round trip time measured by the slave round trip time measurement unit, branch round trip time measured by the branch round trip time measurement unit, and main line round trip time measurement unit A delay time calculation unit that calculates a delay time based on the main line round trip time,
The master transmission unit of the time master device transmits synchronization information serving as a reference value for synchronization time,
Each of the time slave devices is further
A synchronization time calculation unit that calculates a time after the delay time as a synchronization time from a time when the synchronization information is received is provided.

  According to the synchronization system of the present invention, in order to calculate the delay time based on the main line round trip time and the branch line round trip time measured by the branching device, in a logical ring network of any connection form such as an asymmetric double ring network. The synchronization time can be calculated.

Embodiment 1 FIG.
In this embodiment, a synchronization system capable of calculating a synchronization time in a logical ring network of any connection form will be described.

FIG. 1 is a diagram showing an example of a network connection form in which the synchronization system according to this embodiment performs synchronization processing.
The network shown in FIG. 1 includes a time master device 10 (M), a time slave device 20 (Sx), and a branch device 30 (Cx, concentrator). That is, in FIG. 1, M is the time master device 10. In addition, S1, S2, S11, S12, S21, and S22 are time slave devices 20. Further, C1 and C2 are branching devices 30.
The time master device 10 is a device that indicates a reference time.
The time slave device 20 is a device that operates according to the reference time of the time master device 10.
The branch device 30 is a device that branches a route.

In FIG. 1, the time master device 10 (M) and the time slave device 20 (S1, S2) are connected by a double ring. In addition, a part of one of the transmission lines connected in a double ring is branched by the branching device 30 (C1), and the time slave device 20 (S11, S12) is line-connected by a bidirectional transmission line. . Further, a part of one transmission path is branched by the branching device 30 (C2), and the time slave devices 20 (S21, S22) are line-connected by a bidirectional transmission path. That is, when the entire network shown in FIG. 1 is seen, it is a network that can be said to be a tree connection. However, the network shown in FIG. 1 forms an asymmetric double ring network because the line-connected networks are connected by bidirectional transmission paths.
In this embodiment, as described above, synchronization processing in a network in which all connection forms are mixed will be described.

  Below, the function and operation | movement of the time master apparatus 10, the time slave apparatus 20, and the branch apparatus 30 are demonstrated 1stly. Second, an example of the operation of the synchronization system will be described using the network shown in FIG. Third, by performing the synchronization process described below, it is shown that each time slave device 20 is operating according to the reference time of the time master device 10, that is, synchronized.

First, functions and operations of the time master device 10, the time slave device 20, and the branch device 30 will be described.
First, the function of the time master device 10 will be described with reference to FIG. FIG. 2 is a functional block diagram showing functions of the time master device 10.
The time master device 10 is a device that indicates a reference time. The time master device 10 generates a synchronization message (measurement information, offset information, and synchronization information described below) and transmits it to the network. The time master device 10 may be connected to two devices as shown in FIG. When the time master device 10 is connected to two devices, the time master device 10 is connected to a port different from each device. Here, one port is called an IN port and the other port is called an OUT port. In FIG. 1, the respective ports are shown as IN and OUT.
The time master device 10 includes a master transmission unit 11, a master reception unit 12, a loopback unit 13, a master round trip time measurement unit 14, and a master storage unit 15.
The master transmission part 11 transmits the message for a synchronization of the measurement information for measuring communication time, the offset information including offset time, and the synchronous information used as the reference value of synchronous time to a network via a communication apparatus.
The master receiving unit 12 receives the synchronization message returned through the network via the communication device.
When the master receiver 12 receives the measurement information from a port different from the port from which the master transmitter 11 has transmitted the measurement information, the loopback unit 13 communicates the measurement information to the port from which the master receiver 12 has received the measurement information. Transmit (loop back) through the device. In other words, when the master receiving unit 12 receives the measurement information from a device different from the device from which the master transmitting unit 11 has transmitted the measurement information, the measurement information is transmitted to the port from which the master receiving unit 12 has received the measurement information via the communication device. Send (loop back).
The master round trip time measurement unit 14 measures the master round trip time until the measurement information transmitted by the master transmission unit 11 returns again through the network. That is, the master round-trip time from when the master transmission unit 11 transmits the measurement information to when the master reception unit 12 receives the measurement information from the port that transmitted the measurement information is measured. In particular, the master round-trip time measurement unit 14 determines the master round-trip time from when the master transmission unit 11 transmits measurement information to when the master transmission unit 11 receives measurement information from the same port as the port through which measurement information is transmitted. measure. That is, the master round-trip time measuring unit 14 determines the master round-trip time from when the master transmitting unit 11 transmits the measurement information to when the master transmitting unit 11 receives the measurement information from the same device as the device that transmitted the measurement information. measure.
The master storage unit 15 stores the correction time included in the synchronization message received by the master reception unit 12 in the storage device at a predetermined timing. Details will be described in the description of the operation of the time master device 10.

Next, the operation of the time master device 10 will be described based on FIG. 1 and FIG. FIG. 3 is a process outline diagram of the time master device 10.
In FIG. 3, the protocol processing unit included in the time master device 10 has a function of generating a synchronization message and sending it to the network. That is, the protocol processing unit is a general term for a functional group including the master transmission unit 11, the master reception unit 12, the loopback unit 13, the master round-trip time measurement unit 14, and the master storage unit 15 described above. A certain amount of processing time is spent on generating and sending messages to the network.
Here, it is assumed that the master transmission unit 11 transmits a synchronization message to the OUT port. In FIG. 1, the message transmitted to the OUT port returns to M from the IN port via M, C1, S11, C2, S21, S22, S21, C2, S12, C2, S11, C1, S1, and S2. That is, the master receiving unit 12 receives the synchronization message transmitted to the OUT port from the IN port.
As described above, the synchronization message includes measurement information (Measure frame), offset information (Offset frame), and synchronization information (Sync frame). The configuration of each message will be described later. The operation of the time master device 10 is divided into measurement information transmission time processing, offset information transmission time processing, and synchronization information transmission time processing for each type of synchronization message to be transmitted.

The measurement information transmission process will be described.
The master transmission unit 11 transmits measurement information including the correction time from the OUT port to the network. Then, the master receiving unit 12 receives the measurement information transmitted from the OUT port and returned around the network from the IN port.
When the loopback unit 13 receives the measurement information from the IN port, the loopback unit 13 loops back the measurement information and sends it out from the IN port. In FIG. 1, the looped back measurement information returns to M from the OUT port via M, S2, S1, and C1. That is, the master receiver 12 receives measurement information from the OUT port again.
Here, the master round trip time measurement unit 14 measures the master round trip time “T” from when the master transmission unit 11 transmits the measurement information to the OUT port until the measurement information is received from the OUT port.
Then, the master storage unit 15 stores the correction time included in the measurement information received from the OUT port as the master correction time in the storage device.

The offset information transmission process will be described.
After the above-described measurement information transmission processing is completed, the master transmission unit 11 adds the master round-trip time measured by the master round-trip time measurement unit 14 and the correction time stored in the master storage unit 15 and divides this by two. The offset time is calculated by subtracting the obtained value (B in FIG. 3) from a predetermined synchronization point (A in FIG. 3). Then, offset information including the calculated offset time is transmitted from the OUT port to the network.

The synchronization information transmission process will be described.
After the offset information transmission time process is completed, the master transmission unit 11 transmits synchronization information. The synchronization information is a message for the time slave device 20 to take the synchronization timing, and is periodically transmitted.

Next, the function of the time slave device 20 will be described with reference to FIG. FIG. 4 is a functional block diagram showing functions of the time slave device 20.
The time slave device 20 is a device that operates according to the reference time of the time master. The time slave device 20 calculates a synchronization time for synchronizing processing timing with another device from the synchronization message transmitted by the time master device 10.
The time slave device 20 includes a slave transmission unit 21, a slave reception unit 22, a slave storage unit 23, a slave round-trip time measurement unit 24, a delay time calculation unit 25, and a synchronization time calculation unit 26.
The slave transmission unit 21 transmits the synchronization message transmitted by the master transmission unit 11 of the time master device 10 to the next device via the communication device.
The slave receiver 22 receives the synchronization message transmitted by the master transmitter 11 of the time master device 10 via the communication device.
The slave storage unit 23 stores the correction time, the offset time, and the like included in the synchronization message received by the slave reception unit 22 in a storage device at a predetermined timing. Details will be described in the description of the operation of the time slave device 20.
The slave round trip time measurement unit 24 measures the slave round trip time from when the slave reception unit 22 receives the measurement information to when the measurement information is transmitted from the port at which the slave reception unit 22 receives the measurement information. In other words, the slave round-trip time measuring unit 24 performs the slave round-trip from the time when the slave receiving unit 22 receives the measurement information to the time when the slave transmitting unit 21 transmits the measurement information to the device that has received the measurement information. Measure time. That is, when the slave reception unit 22 receives measurement information from the IN port, the slave round-trip time measurement unit 24 measures the slave round-trip time until the slave transmission unit 21 transmits the measurement information from the IN port. When the time slave device 20 is provided at a location that is not the end of the network (for example, S1, S2, S11, S21 in FIG. 1), the slave round trip time measuring unit 24 receives the measurement information from the IN port by the slave receiving unit 22. After the reception, the slave reception unit 22 receives the measurement information from the OUT port again, and measures the slave round trip time from the IN port until the slave transmission unit 21 transmits the measurement information. When the time slave device 20 is provided at the end of the network (for example, S12 and S22 in FIG. 1), the slave round trip time measuring unit 24 receives the measurement information from the IN port and then the IN port after the slave receiving unit 22 receives the measurement information. The slave reciprocation time until the slave transmitter 21 loops back (transmits) the measurement information is measured.
The delay time calculation unit 25 calculates the delay time by the processing device. The method by which the delay time calculation unit 25 calculates the delay time will be described in the description of the operation of the time slave device 20.
The synchronization time calculation unit 26 calculates the time after the delay time calculated by the delay time calculation unit 25 from the time when the slave reception unit 22 receives the synchronization information from the IN port as the synchronization time.

Next, the operation of the time slave device 20 will be described based on FIG. 1 and FIG. FIG. 5 is a process outline diagram of the time slave device 20.
In FIG. 5, the protocol processing unit included in the time slave device 20 has a function of generating a synchronization message and sending it to the network. That is, the protocol processing unit is a general term for a functional group including the slave transmission unit 21, the slave reception unit 22, the slave storage unit 23, the slave round-trip time measurement unit 24, the delay time calculation unit 25, and the synchronization time calculation unit 26 described above. The protocol processing unit spends a certain processing time in generating a synchronization message and sending it to the network.
The operation of the time slave device 20 is divided into measurement information reception processing, offset information reception processing, and synchronization information reception processing for each type of synchronization message to be received.

The measurement information reception process will be described.
The slave receiver 22 receives the measurement information transmitted by the master transmitter 11 of the time master device 10 from the IN port. Then, the slave round trip time measuring unit 24 starts measuring the slave round trip time “T”. Further, when receiving the measurement information from the IN port, the slave storage unit 23 stores the correction time included in the measurement information as a first correction time (B in FIG. 5) in the storage device. Then, the slave transmission unit 21 transmits measurement information from the OUT port to the network.
When the slave receiving unit 22 receives the measurement information transmitted from the OUT port again from the OUT port, the slave storage unit 23 stores the correction time included in the measurement information as the second correction time (A in FIG. 5) in the storage device. To do. Then, the slave transmission unit 21 transmits measurement information from the IN port to the network. The slave round trip time measuring unit 24 ends the measurement of the slave round trip time “T” when outputting the measurement information from the IN port. When the time slave device 20 is a device provided at the end of the line connection, the slave transmission unit 21 loops back the received measurement information. That is, the measurement information received from the IN port by the slave receiver 22 is transmitted from the IN port by the slave transmitter 21. In this case, the same correction time as the first correction time is stored in the second correction time, and the slave reciprocation time “T” stores the time from when the measurement information is received until it is transmitted.

The offset information reception process will be described.
The slave receiver 22 receives the offset information transmitted from the master transmitter 11 of the time master device 10 from the IN port. The slave storage unit 23 stores the offset time included in the offset information as a slave offset time in the storage device. Here, the delay time calculation unit 25 adds the time obtained by subtracting the first correction time from the second correction time stored in the slave storage unit 23 ("AB" in FIG. 5) and the slave round-trip time. A time obtained by adding the time divided by 2 and the slave offset time is calculated as a delay time (Delay value).
Further, when the slave receiving unit 22 receives the offset information transmitted from the OUT port again from the OUT port, the slave transmitting unit 21 transmits the offset information from the IN port to the network.
When the time slave device 20 is a device provided at the end of the line connection, the slave transmission unit 21 loops back the received offset information.

A process at the time of receiving synchronous information will be described.
The slave receiver 22 receives the synchronization information transmitted from the master transmitter 11 of the time master device 10 from the IN port at a predetermined cycle. The synchronization time calculation unit 26 calculates the time after the delay time as the synchronization time from the time when the synchronization information is received. Here, the calculated synchronization time coincides with the synchronization point in the time master device 10. The fact that the calculated synchronization time coincides with the synchronization point in the time master device 10 will be described later. Then, the slave transmission unit 21 transmits synchronization information from the OUT port to the network.

Next, the function of the branch device 30 will be described with reference to FIG. FIG. 6 is a functional block diagram illustrating functions of the branch device 30.
The branch device 30 is a device that branches a route.
The branch device 30 includes a branch device transmission unit 31, a branch device reception unit 32, a branch device storage unit 33, a branch line round trip time measurement unit 34, a main line round trip time measurement unit 35, a correction time update unit 36, and an offset time update unit 37. .
The branch device transmission unit 31 transmits the synchronization message transmitted by the master transmission unit 11 of the time master device 10 to the next device via the communication device.
The branch device reception unit 32 receives the synchronization message transmitted by the master transmission unit 11 of the time master device 10 via the communication device.
The branch device storage unit 33 stores the correction time, the offset time, and the like included in the synchronization message received by the branch device reception unit 32 in a storage device at a predetermined timing. Details will be described in the description of the operation of the branch device 30.
The branch line round trip time measurement unit 34 receives the measurement information from the branch device reception unit 32 and then receives the measurement information again through the branch network that is the branch destination network. The branch device reception unit 32 receives the measurement information again. The branch line round trip time until 31 again transmits the measurement information is measured by the processing device. The branch line round trip time measuring unit 34 receives, for example, measurement information from the IN port in FIG. 1 after the branch device receiving unit 32 receives the measurement information from the OUT1 port, and the branch device transmitting unit 31 transmits the measurement information from the OUT1 port. Is again received, and the branch line round trip time until the branching device transmission unit 31 transmits the measurement information from the OUT2 port is measured.
The main line round trip time measuring unit 35 receives the measurement information from the branch device receiving unit 32, then the measurement information is received again by the branch device receiving unit 32 through the main network, and the slave transmission unit 21 transmits the measurement information again. The main line round-trip time until completion is measured by the processing device. The main line round trip time measuring unit 35 receives, for example, measurement information from the IN port by the branching device receiving unit 32, then receives the measurement information from the OUT2 port again by the branching device receiving unit 32, and receives the measurement information from the IN port. The main line round trip time until the branching device transmission unit 31 transmits is measured.
The correction time update unit 36 updates the correction time included in the measurement information by the processing device based on a predetermined condition. A method for updating the correction time of the correction time update unit 36 will be described in the description of the operation of the branch device 30.
The offset time update unit 37 updates the offset time included in the offset information by the processing device based on a predetermined condition. The offset time update method of the offset time update unit 37 will be described in the description of the operation of the branch device 30.

Next, based on FIG. 1 and FIG. 7, operation | movement of the branch apparatus 30 is demonstrated. FIG. 7 is a process outline diagram of the branch device 30.
The operation of the branching device 30 is divided into measurement information reception processing, offset information reception processing, and synchronization information reception processing for each type of synchronization message to be received.
In the following description, it is assumed that the main network is branched to one branch network. Here, a network connected to the OUT1 port is a branch network, and a network connected to the IN port and the OUT2 port is a main network.

The measurement information reception process will be described.
The branch device reception unit 32 receives the measurement information transmitted from the master transmission unit 11 of the time master device 10 from the IN port. Then, the branch line round trip time measuring unit 34 starts measuring the branch line round trip time “T2”, and the main line round trip time measuring unit 35 starts measuring the main line round trip time “T1”. Further, when the measurement information is received from the IN port, the branch device storage unit 33 stores the correction time included in the measurement information in the storage device as the reception correction time. Then, the branch device transmission unit 31 transmits the measurement information from the OUT1 port to the branch network.
The branching device receiving unit 32 receives the measurement information that has returned again through the branch network from the OUT1 port. Here, the branch device storage unit 33 stores the correction time included in the measurement information as a branch line correction time in the storage device. Then, the branching device transmitter 31 transmits the measurement information from the OUT2 port to the main line network. The branch line round trip time measurement unit 34 ends the measurement of the branch line round trip time “T2” when transmitting measurement information from the OUT2 port. In addition, the correction time update unit 36 updates the correction time included in the measurement information with the time obtained by adding the reception correction value stored in the branch device storage unit 33 and the branch line round trip time “T2” as a new correction time.
The branching device receiving unit 32 receives the measurement information that has returned again through the main line network from the OUT2 port. Then, the branch device transmission unit 31 transmits the measurement information from the IN port to the main line network. The main line round trip time measuring unit 35 ends the measurement of the main line round trip time “T1” when transmitting to the IN port.

The offset information reception process will be described.
The branch device reception unit 32 receives the offset information transmitted by the master transmission unit 11 of the time master device 10 from the IN port. The branch device storage unit 33 stores the offset time included in the offset information in the storage device as the branch device offset time. Further, the offset time update unit 37 subtracts the branch line correction time (B in FIG. 7) stored in the branch device storage unit 33 from the main line round-trip time “T1” (A in FIG. 7) measured by the main line round-trip time measurement unit 35. The offset time of the offset information is updated using a time obtained by adding the time divided by 2 and the branch device offset time as a new offset time. That is, “((T1−branch correction time) / 2) + branch device offset time” is set as a new offset time. Then, the branch device transmission unit 31 transmits the offset information from the OUT1 port to the branch network.
The branching device receiving unit 32 receives the offset information that has returned around the branch network again from the OUT1 port. Here, the offset time update unit 37 updates the offset information using the branch device offset time as a new offset time. Then, the branch device transmission unit 31 transmits the offset information from the OUT2 port to the main line network.
When the branch device receiving unit 32 receives the offset information that has returned again around the main network from the OUT2 port, the branch device transmitting unit 31 transmits the offset information from the IN port to the main network.

A process at the time of receiving synchronous information will be described.
The branch device receiver 32 does not perform any particular processing when the synchronization information transmitted from the master transmitter 11 of the time master device 10 is received from the IN port, and the branch device transmitter 31 branches the synchronization information from the OUT1 port. Send to the network.
Further, when the branch device receiving unit 32 receives the synchronization information that has returned again around the branch network from the OUT1 port, the branch device transmitting unit 31 does not perform any processing, and the branch device transmitting unit 31 sends the synchronization information from the OUT2 port to the main network. Send.
Further, when the branching device receiving unit 32 receives the synchronization information that has returned again around the main network from the OUT2 port, no processing is performed, and the branching device transmitting unit 31 sends the synchronization information from the IN port to the main network. Send.
That is, the branching device 30 does not perform any particular processing when receiving the synchronization information and transfers it to the next device.

Next, a frame format of a synchronization message transmitted by the time master device 10 will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of the frame format of the synchronization message.
The synchronization message shown in FIG. 8 includes a header, a frame type, a message ID (identifier), and a payload.
Information such as a transmission destination address is stored in the header.
As the frame type, an identifier such as Measurement indicating measurement information, Offset indicating offset information, Sync indicating synchronization information, or the like is stored.
The message ID stores an identifier that can uniquely identify the message. Each device can confirm that the message is the same as the previously received message by referring to the message ID.
When the payload is measurement information, the correction time is stored, and when the payload is offset information, the offset time is stored. That is, in the above description, the correction time included in the measurement information is the correction time stored in the payload of the measurement information frame. Similarly, the offset time included in the offset information is the offset time stored in the payload of the offset information frame.

Second, an example of the operation of the synchronization system will be described using the network shown in FIG.
9 and 10 are diagrams showing an outline of the synchronization process of the network shown in FIG. FIG. 9 is a diagram showing a flow of measurement information and offset information, and FIG. 10 is a diagram showing a flow of synchronization information. In FIGS. 9 and 10, time advances from the top to the bottom. Further, each synchronization message moves according to a horizontal arrow. The value described in the horizontal arrow indicates the correction time if it is an arrow indicating measurement information, and indicates the offset time if it is offset information. The vertical arrows indicate the master round trip time, slave round trip time, branch round trip time, and main line round trip time.
FIG. 11 is a diagram showing the correction time, offset time, and delay time of each time slave device 20 when the network synchronization processing shown in FIG. 1 is performed.
Hereinafter, description will be given in the order of processing. In the following description, the internal processing time such as transmission and reception in each device is set to 0 for simplicity.

(1) First, measurement information propagates. That is, the measurement information transmission process of the time master device 10, the measurement information reception process of the time slave device 20, and the measurement information reception process of the branch device 30 are executed. Here, the correction time included in the measurement information is 0.
The master transmission unit 11 of the time master device 10 (M) transmits measurement information including a predetermined correction time from the OUT port to the network. Then, the measurement information reaches the branch device 30 (C1). The branch device storage unit 33 of the branch device 30 (C1) stores the correction time “0” included in the measurement information as the correction time at the time of reception. Then, the branch device transmitter 31 of the branch device 30 (C1) transmits measurement information from the OUT1 port.
The measurement information reaches the time slave device 20 (S11). The slave storage unit 23 of the time slave device 20 (S11) stores the correction time “0” included in the measurement information as the first correction time. And the slave transmission part 21 of the time slave apparatus 20 (S11) transmits measurement information.
The measurement information reaches the branch device 30 (C2). The branch device storage unit 33 of the branch device 30 (C2) stores the correction time “0” of the measurement information as the reception correction time. The branch device transmitter 31 of the branch device 30 (C2) transmits measurement information from the OUT1 port.
The measurement information reaches the time slave device 20 (S21). The slave storage unit 23 of the time slave device 20 (S21) stores the correction time “0” of the measurement information as the first correction time. And the slave transmission part 21 of the time slave apparatus 20 (S21) transmits measurement information.
The measurement information reaches the time slave device 20 (S22). The slave storage unit 23 of the time slave device 20 (S22) stores the correction time “0” of the measurement information as the first correction time. And the slave transmission part 21 of the time slave apparatus 20 (S22) transmits measurement information. Here, since the time slave device 20 (S22) is a device at the end of a network connected in a line, it loops back the measurement information. That is, the time slave device 20 (S22) transmits measurement information received from the IN port from the IN port. Therefore, the slave storage unit 23 of the time slave device 20 (S22) stores the correction time “0” of the measurement information as the second correction time. In addition, the slave round trip time measuring unit 24 of the time slave device 20 (S22) measures the time from the reception of the measurement information to the transmission as the slave round trip time. Here, since the internal processing time is 0 as described above, the slave round trip time measuring unit 24 of the time slave device 20 (S22) measures “0” as the slave round trip time.
The measurement information looped back to the time slave device 20 (S22) reaches the time slave device 20 (S21) again. The slave storage unit 23 of the time slave device 20 (S21) stores the correction time “0” of the measurement information as the second correction time. The slave round trip time measuring unit 24 of the time slave device 20 (S21) measures “Ds21” as the slave round trip time. And the slave transmission part 21 of the time slave apparatus 20 (S21) transmits measurement information.

The measurement information reaches the branch device 30 (C2). The branch device storage unit 33 of the branch device 30 (C2) stores the correction time “0” included in the measurement information as a branch line correction time. The branch line round trip time measuring unit 34 of the branch device 30 (C2) measures “D21” as the branch line round trip time. Moreover, the correction time update unit 36 of the branch device 30 (C2) adds the correction value “0” at the time of reception stored in the branch device storage unit 33 of the branch device 30 (C2) and the measured branch line round trip time “D21”. The correction time included in the measurement information is updated with the new time “D21” as the new correction time. Then, the branch device transmitter 31 of the branch device 30 (C2) transmits measurement information from the OUT2 port. Here, the correction time included in the measurement information transmitted by the branch device 30 (C2) is “D21”.
The measurement information reaches the time slave device 20 (S12). The slave storage unit 23 of the time slave device 20 (S12) stores “D21” as the first correction time. Since the time slave device 20 (S22) is a device at the end of the network connected in a line, it loops back the measurement information. Therefore, the slave storage unit 23 of the time slave device 20 (S12) stores the correction time “D21” of the measurement information as the second correction time. The slave round trip time measuring unit 24 of the time slave device 20 (S12) measures “0” as the slave round trip time.

The measurement information looped back to the time slave device 20 (S12) reaches the branch device 30 (C2) again. The main line round trip time measuring unit 35 of the branch device 30 (C2) measures “D22” as the main line round trip time. Then, the branch device transmitter 31 of the branch device 30 (C2) transmits measurement information from the IN port.
The measurement information reaches the time slave device 20 (S11) again. When the measurement information is received, the slave storage unit 23 of the time slave device 20 (S11) stores the correction time “D21” of the measurement information as the second correction time. The slave round trip time measuring unit 24 of the time slave device 20 (S11) measures “Ds11” as the slave round trip time. And the slave transmission part 21 of the time slave apparatus 20 (S11) transmits measurement information.
The measurement information reaches the branch device 30 (C1) again. The branch device storage unit 33 of the branch device 30 (C1) stores the correction time “D21” included in the measurement information as a branch line correction time. Further, the branch line round trip time measuring unit 34 of the branching device 30 (C1) measures “D11” as the branch line round trip time. Further, the correction time update unit 36 of the branch device 30 (C1) adds the reception correction value “0” stored in the branch device storage unit 33 of the branch device 30 (C1) and the measured branch round trip time “D11”. The correction time included in the measurement information is updated with the new time “D11” as the new correction time. Then, the branch device transmitter 31 of the branch device 30 (C2) transmits measurement information from the OUT2 port. Here, the correction time included in the measurement information transmitted by the branch device 30 (C1) is “D11”.
The measurement information reaches the time slave device 20 (S1). When the measurement information is received, the slave storage unit 23 of the time slave device 20 (S1) stores “D11” as the first correction time. And the slave transmission part 21 of the time slave apparatus 20 (S1) transmits measurement information.
The measurement information reaches the time slave device 20 (S2). When the measurement information is received, the slave storage unit 23 of the time slave device 20 (S2) stores “D11” as the first correction time. And the slave transmission part 21 of the time slave apparatus 20 (S2) transmits measurement information.

The measurement information transmitted from the time slave device 20 (S2) reaches the time master device 10 (M). Here, the master receiver 12 of the time master device 10 (M) receives the measurement information from the IN port. That is, the measurement information is received from an IN port that is a port different from the OUT port transmitted by the master transmission unit 11. That is, the measurement information is received from the time slave device 20 (S2), which is a device different from the branch device 30 (C1) transmitted by the master transmission unit 11. Therefore, the loopback unit 13 of the time master device 10 (M) loops back the measurement information. That is, the loopback unit 13 of the time master device 10 (M) transmits measurement information to the network again from the IN port that has received the measurement information.
The measurement information reaches the time slave device 20 (S2) again. The slave storage unit 23 of the time slave device 20 (S2) stores “D11” as the second correction time. The slave round trip time measuring unit 24 of the time slave device 20 (S2) measures “Ds2” as the slave round trip time. And the slave transmission part 21 of the time slave apparatus 20 (S2) transmits measurement information.
The measurement information reaches the time slave device 20 (S1) again. The slave storage unit 23 of the time slave device 20 (S1) stores “D11” as the second correction time. The slave round trip time measuring unit 24 of the time slave device 20 (S1) measures “Ds1” as the slave round trip time. And the slave transmission part 21 of the time slave apparatus 20 (S2) transmits measurement information.
The measurement information reaches the branch device 30 (C1). The main line round trip time measuring unit 35 of the branch device 30 (C1) measures “D12” as the main line round trip time. Then, the branch device transmitter 31 of the branch device 30 (C1) transmits measurement information from the IN port.
Then, the measurement information reaches the time master device 10 (M). That is, the master receiver 12 of the time master device 10 (M) receives the measurement information from the OUT port that is the same port as the OUT port transmitted by the master transmitter 11. That is, the measurement information is received from the branch device 30 (C1) that is the same device as the branch device 30 (C1) transmitted by the master transmitter 11. Therefore, the master round trip time measuring unit 14 of the time master device 10 (M) measures “Dm” as the master round trip time. In addition, the master storage unit 15 of the time master device 10 (M) stores the correction time included in the measurement information as the master correction time.

(2) The offset information propagates. That is, the offset information transmission time process of the time master device 10, the offset information reception time processing of the time slave device 20, and the offset information reception time processing of the branch device 30 are executed.
The master transmission unit 11 of the time master device 10 (M) adds the master round-trip time “Dm” measured by the master round-trip time measurement unit 14 and the master correction time stored in the master storage unit 15 and divides this by two. The calculated value (B in FIG. 3) is subtracted from a predetermined synchronization point (A in FIG. 3) to calculate an offset time. Here, it is assumed that the calculated offset time is “Offset”. Then, offset information including the offset time “Offset” is transmitted from the OUT port to the network.
The offset information reaches the branch device 30 (C1). The branch device storage unit 33 of the branch device 30 (C1) stores the offset time “Offset” included in the offset information as the branch device offset time. Further, the offset time update unit 37 of the branch device 30 (C1) subtracts the branch line correction time “D21” from the main line round-trip time “D12” and divides it by 2 “(D12−D21) / 2 (= Oc1)”. Then, the offset time of the offset information is updated with the time “Offset + Oc1” obtained by adding the branch device offset time “Offset” as a new offset time. Then, the branch device transmitter 31 of the branch device 30 (C1) transmits the offset information from the OUT1 port. That is, the offset time included in the offset information transmitted by the branch device 30 (C1) is “Offset + Oc1”.
The offset information reaches the time slave device 20 (S11). The slave storage unit 23 of the time slave device 20 (S11) stores the offset time “Offset + Oc1” (Oc1 = (D12−D21) / 2) included in the offset information as the slave offset time. Further, the delay time calculation unit 25 of the time slave device 20 (S11) calculates a time “D21” obtained by subtracting the first correction time “0” from the second correction time “D21” and the slave round-trip time “Ds11”. The time “(Ds11 / 2) + Offset + (D12 / 2)” obtained by adding the time “(D21 + Ds11) / 2” added by 2 and the offset time “Offset + (D12−D21) / 2” as the delay time calculate. And the slave transmission part 21 of the time slave apparatus 20 (S11) transmits offset information.

The offset information reaches the branch device 30 (C2). The branch device storage unit 33 of the branch device 30 (C2) stores the offset time “Offset + Oc1” included in the offset information as the branch device offset time. Further, the offset time update unit 37 calculates a time “D22 / 2 (= Oc2)” obtained by subtracting the branch line correction time “0” from the main line round-trip time “D22” and dividing by 2 and a branch device offset time “Offset + Oc1”. The offset time of the offset information is updated using the added time “Offset + Oc1 + Oc2” as a new offset time. Then, the branch device transmitter 31 of the branch device 30 (C2) transmits the offset information from the OUT1 port. That is, the offset time included in the offset information transmitted by the branch device 30 (C2) is “Offset + Oc1 + Oc2”.
The offset information reaches the time slave device 20 (S21). When the offset information is received, the slave storage unit 23 of the time slave device 20 (S21) includes the offset time “Offset + Oc1 + Oc2” (Oc1 = (D12−D21) / 2, Oc2 = D22 / 2) included in the offset information as the slave offset time. ) Is stored. Further, the delay time calculation unit 25 of the time slave device 20 (S21) calculates a time “0” obtained by subtracting the first correction time “0” from the second correction time “0” and the slave round-trip time “Ds21”. Add time “Ds21 / 2” divided by 2 and offset time “Offset + (D12−D21) / 2 + D22 / 2” plus time “(Ds21 / 2) + Offset + (D12−D21 + D22) / 2” Calculate as time. And the slave transmission part 21 of the time slave apparatus 20 (S21) transmits offset information.
The offset information reaches the time slave device 20 (S22). The slave storage unit 23 of the time slave device 20 (S22) stores the offset time “Offset + Oc1 + Oc2” included in the offset information as the slave offset time. Further, the delay time calculation unit 25 of the time slave device 20 (S22) calculates a time “0” obtained by subtracting the first correction time “0” from the second correction time “0” and the slave round-trip time “0”. A time “Offset + (D12−D21 + D22 / 2)” obtained by adding the time “0” divided by 2 and the offset time “Offset + (D12−D21) / 2 + D22 / 2” is calculated as the delay time.

Since the time slave device 20 (S22) is a device provided at the end of the line connection, it loops back the offset information. The offset information reaches the time slave device 20 (S21). The time slave device 20 (S21) does not particularly process the received offset information and transmits it to the network.
The offset information reaches the branch device 30 (C2). The offset time update unit 37 of the branch device 30 (C2) updates the offset time of the offset information using the stored branch device offset time “Offset + Oc1” as a new offset time. Then, the branch device transmitter 31 of the branch device 30 (C2) transmits the offset information from the OUT2 port. That is, the offset time included in the offset information transmitted by the branch device 30 (C2) is “Offset + Oc1”.
The offset information reaches the time slave device 20 (S12). The slave storage unit 23 of the time slave device 20 (S12) stores the offset time “Offset + Oc1” (Oc1 = (D12−D21) / 2) included in the offset information as the slave offset time. Further, the delay time calculation unit 25 of the time slave device 20 (S12) calculates a time “0” obtained by subtracting the first correction time “D21” from the second correction time “D21” and the slave round-trip time “0”. The time “Offset + (D12−D21) / 2” obtained by adding the time “0” divided by 2 and the offset time “Offset + (D12−D21) / 2” is calculated as the delay time.

Since the time slave device 20 (S12) is a device provided at the end of the line connection, it loops back the offset information. Then, the offset information reaches the branch device 30 (C2). The branching device 30 (C2) does not particularly process the received offset information and transmits it to the network.
The offset information reaches the time slave device 20 (11). The time slave device 20 (S11) also transmits the received offset information to the network without performing any particular processing.
The offset information reaches the branch device 30 (C1). When the offset information passes through the branch device 30 (C1), the offset time update unit 37 of the branch device 30 (C1) updates the offset time of the offset information using the stored branch device offset time “Offset” as a new offset time. To do. Then, the branch device transmitter 31 of the branch device 30 (C1) transmits the offset information from the OUT2 port. That is, the offset time included in the offset information transmitted by the branch device 30 (C1) is “Offset”.
The offset information reaches the time slave device 20 (S1). The slave storage unit 23 of the time slave device 20 (S1) stores the offset time “Offset” included in the offset information as the slave offset time. Further, the delay time calculation unit 25 of the time slave device 20 (S1) obtains the time “0” obtained by subtracting the first correction time “D11” from the second correction time “D11” and the slave round-trip time “Ds1”. The time “Ds1 / 2 + Offset” obtained by adding the time “Ds1 / 2” divided by 2 and the offset time “Offset” is calculated as the delay time. Then, the slave transmission unit 21 of the time slave device 20 (S1) transmits the offset information. The offset information reaches the time slave device 20 (S2). The slave storage unit 23 of the time slave device 20 (S2) stores the offset time “Offset” included in the offset information as the slave offset time. Further, the delay time calculation unit 25 of the time slave device 20 (S2) calculates a time “0” obtained by subtracting the first correction time “D11” from the second correction time “D11” and the slave round-trip time “Ds2”. The time “Ds2 / 2 + Offset” obtained by adding the time “Ds2 / 2” divided by 2 and the offset time “Offset” is calculated as the delay time. Then, the slave transmission unit 21 of the time slave device 20 (S2) transmits the offset information, and the offset information reaches the time master device 10 (M).

(3) The synchronization information propagates. That is, the synchronization information transmission process of the time master device 10, the synchronization information reception process of the time slave device 20, and the synchronization information reception process of the branch device 30 are executed.
The master transmission unit 11 of the time master device 10 (M) transmits synchronization information. Then, it reaches the time slave device 20 (S11) via the branch device 30 (C1). Furthermore, it reaches the time slave device 20 (S21 and S22) via the branch device 30 (C2). Furthermore, the time slave device 20 (S22) reaches the time slave device 20 (S12) via the time slave device 20 (S21) and the branch device 30 (C2). Further, it reaches the time slave device 20 (S1 and S2) via the branch device 30 (C2), the time slave device 20 (11), and the branch device 30 (C1), and finally the time master device 10 ( Return to M).
When the synchronization information passes through the branch device 30 (C1 and C2), the branch device 30 (C1 and C2) transmits the received synchronization information to the network without performing any particular processing. Further, the synchronization time calculation unit 26 of each time slave device 20 calculates the synchronization time after the delay time after receiving the synchronization information from the IN port.
When the time master device 10, the time slave device 20, and the branch device 30 perform the above operations, the time slave devices 20 can be synchronized.

Third, by performing the synchronization processing described above, it is indicated that each time slave device 20 is operating according to the reference time of the time master device 10, that is, synchronized.
FIG. 12 is a diagram illustrating a propagation time from when the time master device 10 (M) transmits the synchronization information until each time slave device 20 receives the synchronization information.
If the propagation time to each time slave device 20 and the delay time calculated by each time slave device 20 are added, “(Dm + D11) / 2 + Offset” is obtained for any time slave device 20. That is, both are the same time. Therefore, it can be seen that the synchronization times calculated by the respective time slave devices 20 are the same time.

  As described above, even if the synchronization system according to this embodiment is an asymmetrical double ring network, all devices can have the same time timing. In the synchronization system according to this embodiment, all devices can have the same time timing regardless of the connection form of the network. That is, in the synchronization system according to this embodiment, all devices can keep the same time timing without recognizing the network connection form.

  The master transmission unit 11 of the time master device 10 may transmit measurement information and offset information when the network is operating (network configuration), and may transmit only synchronization information after the network is operating. That is, the delay time of each time slave device 20 may be measured during network operation, and the devices may be synchronized at a predetermined interval after the network operation.

Further, the master transmission unit 11 of the time master device 10 may transmit measurement information, offset information, and synchronization information to both the OUT port and the IN port. That is, in the above description, the measurement information, the offset information, and the synchronization information are transmitted only to the branch device 30 (C1) connected to the OUT port side in FIG. However, the measurement information, offset information, and synchronization information may be transmitted not only to the branch device 30 (C1) connected to the OUT port side but also to the time slave device 20 (S2) connected to the IN port side. Absent.
In this case, the delay time calculation unit 25 of each time slave device 20 uses the delay time (first delay time) from the information calculated based on the measurement information transmitted to the OUT port and the offset information transmitted to the OUT port. And a delay time (second delay time) is calculated from information calculated based on the measurement information transmitted to the IN port and the offset information transmitted to the IN port.
The synchronization time calculation unit 26 of each time slave device 20 calculates the time after the first delay time from the time when the synchronization information transmitted to the OUT port is received as the synchronization time (first synchronization time). The time after the second delay time from the time when the synchronization information transmitted to the OUT port is received is calculated as the synchronization time (second synchronization time).
That is, the synchronization system according to this embodiment may calculate the synchronization time for any direction of the double ring.

  In addition, the time slave device 20 may include a port determination unit that determines which of the IN port and the OUT port first received the synchronization information. In this case, the synchronization time calculation unit 26 of the time slave device 20 calculates from the time when the synchronization information is received based on the measurement information and the offset information received first from the device that the port determination unit determines has received the synchronization information. The time after the delayed time is calculated as the synchronization time. In other words, when the port determination unit determines that the synchronization information has been received from the IN port, it is first received from the IN port from the time when the synchronization information is received (in other words, the master transmission unit 11 transmits to the OUT port). ) The time after the delay time calculated based on the measurement information and the offset information is calculated as the synchronization time.

In the above description, the branching device 30 has been described on the assumption that it branches from the main network to one branch network. However, the branch device 30 is not limited to this, and may branch from the main network to two or more branch networks. When branching from a main line network to two or more branch line networks, it is possible to apply the above operation on the assumption that the branch device 30 includes a plurality of branch devices 30.
FIG. 13 is a diagram illustrating an example in which the branching device 30 branches from the main network to two or more branch network. FIG. 13A is an actual network configuration, and FIG. 13B is a diagram illustrating a network configuration when it is assumed that one branch device 30 includes a plurality of branch devices 30.
As shown in FIG. 13A, when the branch device 30 (C) includes an IN port, an OUT1 port, an OUT2 port, and an OUT3 port, the network ahead of the OUT1 port is the first branch network, and from the OUT2 port. The previous network is the second branch network, and the IN port and the OUT3 port are the main network. In addition, a synchronization message is received from the IN port, then transmitted from the OUT1 port to the first branch network, and is received from the OUT1 port again around the first branch network, and then from the OUT2 port to the second branch network. To the second branch network and received from the OUT2 port again, and from the OUT3 port to the main network and again received from the OUT3 port.
In this case, it can be assumed that the branch device 30 (C) is the branch device 30 (Ca) and the branch device 30 (Cb) as shown in FIG. That is, in FIG.13 (b), the part enclosed with the broken line is the branching device 30 (C). The branch device 30 (Ca) has an IN port, an OUT3 port, and an imaginary X port. Branch device 30 (Cb) has a hypothetical Y port, an OUT1 port, and an OUT2 port. In addition, the branch device 30 (Ca) and the branch device 30 (Cb) are connected to each other by an imaginary X port and a Y port. The propagation time between the fictitious X and Y ports is zero.
By thinking in this way, the branching device 30 branches from the main network to the two branch networks by applying the operation of the synchronization processing when the branch device 30 described above branches from the main network to one branch network. In this case, synchronization processing can be performed. Further, even when the branch device 30 branches from the main network to three or more branch networks, the branch device 30 described above is considered by considering that one branch device 30 is a plurality of branch devices 30. Can be applied to the operation of synchronization processing in the case of branching from the main network to one branch network.

To summarize the above description, the synchronization system according to the present embodiment connects devices with a bi-directional transmission path, and on a physical wiring formed in a tree shape via a double ring or line or branch device 30. In a logical ring type network where communication data is terminated by returning to the sender after one round or round trip of all devices,
(A) a time master selecting means for selecting the only time manager (time master device 10) in the network from devices having a frame transmission function;
The device selected as the time master device 10 is
(B1) frame generation means for transmitting a measurement frame, an offset frame, and a synchronization frame;
(B2) Time master time measuring means for measuring the time from transmission to reception of the measurement frame;
(B3) Offset value calculation means for calculating an offset value based on the result of (b2);
(B4) observing the reception port of the measurement frame, and when receiving is first detected from a port different from the port that transmitted the measurement frame, a loopback request means for executing a loopback of the same frame is provided,
The time slave device 20 not selected by the time master device 10 is:
(C1) Time slave time measuring means for measuring the time from reception of the measurement frame to transmission of the measurement frame to the port;
(C2) measurement correction value recording means for recording correction data included in the measurement frame;
(C3) offset value recording means for recording the offset value included in the offset frame;
(C4) delay value calculating means for calculating a synchronization delay value based on the results from (c1) to (c3);
(C5) synchronization correction means for resetting the clock after the delay value of (c4) after receiving the synchronization frame;
The branching device 30 is
(D1) a branching device time measuring means for measuring the round trip time of each path of the measurement frame;
(D2) measurement correction value recording means for recording correction data included in the measurement frame;
(D3) offset value recording means for recording the offset value included in the offset frame;
(D4) Measurement correction value changing means for changing the correction data of the measurement frame based on (d1) and (d2);
(D5) An offset value changing means for changing the offset value of the offset frame based on (d1) and (d3) is provided.

The network synchronization system performs measurement frames and offset frames during network configuration, and periodically transmits only the synchronization frames during normal communication.
Further, the network synchronization device includes the above means in both ring directions.
Furthermore, the network synchronization device monitors a synchronization frame reception port, detects a port change, and automatically switches (c5).

In the synchronization system according to this embodiment, the time master device 10 measures the master round-trip time, the time slave device 20 measures the slave round-trip time, and the branch device 30 measures the branch line round-trip time and the main line round-trip time. The time slave device 20 calculates a delay time from the master round trip time, slave round trip time, branch round trip time, and main line round trip time.
Further, the synchronization system according to this embodiment is synchronized only by passing three types of packets through the network by the time master device 10, the time slave device 20, and the branch device 30 performing the above-described operation. It is characterized by being able to.

Next, the hardware configuration of the time master device 10, the time slave device 20, and the branch device 30 in the above embodiment will be described.
FIG. 14 is a diagram illustrating an example of a hardware configuration of the time master device 10, the time slave device 20, and the branch device 30.
As shown in FIG. 14, the time master device 10, the time slave device 20, and the branch device 30 include a CPU 911 (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, A processor). The CPU 911 is connected to the ROM 913, the RAM 914, the LCD 901 (Liquid Crystal Display), the touch panel 902, the communication board 915, and the magnetic disk device 920 via the bus 912, and controls these hardware devices. Instead of the magnetic disk device 920, a storage device such as an optical disk device or a memory card read / write device may be used.

  The ROM 913 and the magnetic disk device 920 are examples of a nonvolatile memory. The RAM 914 is an example of a volatile memory. The ROM 913 and the RAM 914 are examples of storage devices. The communication board 915 and the touch panel 902 are examples of input devices. The communication board 915 is an example of an output device. Furthermore, the communication board 915 is an example of a communication device. Furthermore, the LCD 901 is an example of a display device.

  An operating system 921 (OS), a window system 922, a program group 923, and a file group 924 are stored in the magnetic disk device 920 or the ROM 913. The programs in the program group 923 are executed by the CPU 911, the operating system 921, and the window system 922.

The program group 923 of the time master device 10 includes the “master transmission unit 11”, “master reception unit 12”, “loopback unit 13”, “master round trip time measurement unit 14”, and “master storage unit 15” in the above description. ”Etc. are stored, and other programs are stored. Similarly, the program group 923 of the time slave device 20 includes “slave transmission unit 21”, “slave reception unit 22”, “slave storage unit 23”, “slave round trip time measurement unit 24”, “ A program for executing the functions described as “delay time calculation unit 25”, “synchronization time calculation unit 26”, “port determination unit”, and the like, and other programs are stored. Similarly, the program group 923 of the branch device 30 includes the “branch device transmitter 31”, “branch device receiver 32”, “branch device storage unit 33”, and “branch round trip time measuring unit 34” in the above description. , A program for executing the functions described as “main line round trip time measurement unit 35”, “correction time update unit 36”, “offset time update unit 37”, and the like, and other programs are stored. The program is read and executed by the CPU 911.
In the file group 924 of the time master device 10, the information, data, signal values, variable values, and parameters described as “master round trip time”, “synchronization point”, etc. in the above description are stored in the “file” or “database”. Stored as each item. Similarly, the file group 924 of the time slave device 20 includes “slave round trip time”, “first correction time”, “second correction time”, “offset time”, “delay time” in the above description. ”,“ Synchronization time ”, and the like, information, data, signal values, variable values, and parameters are stored as items of“ file ”and“ database ”. Similarly, the file group 924 of the branch device 30 includes “branch round trip time”, “main round trip time”, “correction time at reception”, “branch line correction time”, and “branch device offset time” in the above description. The information, data, signal values, variable values, and parameters described above are stored as items of “file” and “database”. The “file” and “database” are stored in a recording medium such as a disk or a memory. Information, data, signal values, variable values, and parameters stored in a storage medium such as a disk or memory are read out to the main memory or cache memory by the CPU 911 via a read / write circuit, and extracted, searched, referenced, compared, and calculated. Used for the operation of the CPU 911 such as calculation / processing / output / printing / display. Information, data, signal values, variable values, and parameters are temporarily stored in the main memory, cache memory, and buffer memory during the operation of the CPU 911 for extraction, search, reference, comparison, calculation, calculation, processing, output, printing, and display. Is remembered.
In addition, the arrows in the flowcharts in the above description mainly indicate input / output of data and signals, and the data and signal values are recorded in a memory of the RAM 914 and other recording media such as an optical disk. Data and signals are transmitted online via a bus 912, signal lines, cables, or other transmission media.

  In addition, what is described as “to part” in the above description may be “to circuit”, “to device”, “to device”, “to means”, and “to function”. It may be “step”, “˜procedure”, “˜processing”. In addition, what is described as “˜device” may be “˜circuit”, “˜device”, “˜equipment”, “˜means”, “˜function”, and “˜step”, “ ~ Procedure "," ~ process ". Furthermore, what is described as “to process” may be “to step”. That is, what is described as “˜unit” may be realized by firmware stored in the ROM 913. Alternatively, it may be implemented only by software, only hardware such as elements, devices, substrates, wirings, etc., or a combination of software and hardware, and further a combination of firmware. Firmware and software are stored in a recording medium such as ROM 913 as a program. The program is read by the CPU 911 and executed by the CPU 911. That is, the program causes a computer or the like to function as the “˜unit” described above. Alternatively, the computer or the like is caused to execute the procedures and methods of “to part” described above.

The figure which shows an example of the connection form of the network which the synchronous system which concerns on Embodiment 1 performs a synchronous process. 4 is a functional block diagram showing functions of the time master device 10. FIG. FIG. 3 is a process overview diagram of the time master device 10. 4 is a functional block diagram showing functions of the time slave device 20. FIG. FIG. 4 is a process outline diagram of the time slave device 20. FIG. 3 is a functional block diagram showing functions of a branch device 30. The processing schematic diagram of the branch device 30. The figure which shows an example of the frame format of the message for a synchronization. The figure which shows the process outline | summary of the synchronous process of the network shown in FIG. The figure which shows the process outline | summary of the synchronous process of the network shown in FIG. The figure which shows the correction time, offset time, and delay time of each time slave apparatus 20 at the time of performing the synchronous process of the network shown in FIG. The figure which shows the propagation time after each time slave apparatus 20 receives synchronous information after the time master apparatus 10 transmits synchronous information in the network shown in FIG. The figure which shows an example in case the branch apparatus 30 branches from a main line network to two or more branch line networks. The figure which shows an example of the hardware constitutions of the time master apparatus 10, the time slave apparatus 20, and the branching apparatus 30.

Explanation of symbols

  10 time master device, 11 master transmission unit, 12 master reception unit, 13 loopback unit, 14 master round trip time measurement unit, 15 master storage unit, 20 time slave device, 21 slave transmission unit, 22 slave reception unit, 23 slave storage Unit, 24 slave round trip time measurement unit, 25 delay time calculation unit, 26 synchronization time calculation unit, 30 branch device, 31 branch device transmission unit, 32 branch device reception unit, 33 branch device storage unit, 34 branch line round trip time measurement unit, 35 main line round trip time measurement unit, 36 correction time update unit, 37 offset time update unit, 901 LCD, 902 touch panel, 911 CPU, 912 bus, 913 ROM, 914 RAM, 915 communication board, 920 magnetic disk device, 921 operating system, 922 Window Sys Beam, 923 program group, 924 files.

Claims (6)

An asymmetric double ring network comprising a main network of a double ring network and a branch network that is branched from one of the rings of the main network and configured with bidirectional transmission lines. The time master device to transmit, the plurality of time slave devices to calculate the synchronization time for synchronizing the processing timing with other devices based on the information transmitted by the time master device, and the branch positions of the main network and the branch network A synchronization system in a network comprising a plurality of devices with a branch device provided in
The time master device is
A master transmitter for transmitting measurement information for measuring communication time;
A master round trip time measuring unit that measures a master round trip time until the measurement information transmitted by the master transmission unit returns again around the network;
Each time slave device of the plurality of time slave devices is
A slave round trip time measuring unit that measures the slave round trip time from the reception of the measurement information to the transmission of the measurement information to the device,
The branching device is
A branch line round trip time measuring unit that measures a branch line round trip time from reception of the measurement information to reception and transmission of the measurement information from the branch network again;
A main line round trip time measuring unit that measures a main line round trip time from receiving the measurement information to receiving and transmitting the measurement information from the main line network again;
Each of the time slave devices is further
Master round trip time measured by the master round trip time measurement unit, slave round trip time measured by the slave round trip time measurement unit, branch round trip time measured by the branch round trip time measurement unit, and main line round trip time measurement unit A delay time calculation unit that calculates a delay time based on the main line round trip time,
The master transmission unit of the time master device transmits synchronization information serving as a reference value for synchronization time,
Each of the time slave devices is further
A synchronization system comprising a synchronization time calculation unit that calculates a time after the delay time from a time when the synchronization information is received as a synchronization time. The master transmitter of the time master device transmits measurement information including the correction time,
Each of the time slave devices is further
When the measurement information is received, the correction time included in the measurement information is stored as the first correction time, and when the measurement information is received again, the correction time included in the measurement information is set to the second correction time. A slave storage unit that stores the correction time
The branching device further includes:
When the measurement information is received, the correction time included in the measurement information is stored as a correction time at the time of reception, and the measurement information travels around the branch network and the measurement information is received again. A branch device storage unit for storing the correction time included in the information as a branch line correction time;
When the measurement information is received again from the branch line network, the correction for updating the correction time of the measurement information is set as a new correction time by adding the round trip time of the branch network to the correction time at the time of reception stored in the branch device storage unit It has a time update unit,
The master transmission unit of the time master device adds the correction time included in the measurement information and the master round-trip time and divides by 2 when the measurement information transmitted by the master transmission unit returns again around the device. The offset information including the offset time, which is the time obtained by subtracting the predetermined time from the synchronization point indicating the predetermined time,
When the slave storage unit of each time slave device receives the offset information, the offset time included in the offset information is stored as a slave offset time,
The branch device storage unit of the branch device stores the offset time included in the offset information as the branch device offset time when the offset information is received,
The branching device further includes:
When transmitting the offset information to the branch network, the offset information is defined as a new offset time obtained by adding the time obtained by subtracting the branch line correction time from the main network round-trip time and dividing by 2 and the branch device offset time. An update time update unit that updates the offset information with the branch device offset time as a new offset time when the offset information is received again from the branch line network.
The delay time calculation unit of each of the time slave devices includes a time obtained by adding the time obtained by subtracting the first correction time from the second correction time stored in the slave storage unit and the slave round-trip time and dividing by two. The synchronization system according to claim 1, wherein the delay time is calculated by adding the slave offset time stored in the slave storage unit. 3. The synchronization system according to claim 2, wherein the master transmission unit of the time master device transmits measurement information and offset information when the network is operating, and transmits only the synchronization information after the network is operating. The time master device is provided in the main network of the double ring network and is connected to two devices, a first device and a second device,
The time master device further includes:
When the master transmission unit transmits measurement information to the first device, the master transmission unit includes a loopback unit that transmits the measurement information to the second device when the measurement information is received from the second device.
The master round trip time measurement unit measures, as the master round trip time, a time until the measurement information is received from the first device when the master transmission unit transmits the measurement information to the first device. The synchronization system according to any one of claims 1 to 3, wherein: The master transmission unit of the time master device transmits measurement information, offset information, and synchronization information to both the first device and the second device,
The delay time calculation unit of each time slave device calculates a first delay time from information calculated based on the measurement information transmitted to the first device and the offset information transmitted to the first device. And calculating the second delay time from the information calculated based on the measurement information transmitted to the second device and the offset information transmitted to the second device,
The synchronization time calculation unit of each time slave device calculates the time after the first delay time from the time when the synchronization information transmitted to the first device is received as the first synchronization time, and 5. The synchronization system according to claim 4, wherein a time after the second delay time is calculated as a second synchronization time from a time at which the synchronization information transmitted to the second device is received. The predetermined time slave device of the plurality of time slave devices is provided in the main network of the double ring network, and is connected to two devices, a third device and a fourth device,
The predetermined time slave device further includes:
A port determination unit for determining whether the synchronization information is received for the first time from the third device or the fourth device;
The synchronization time calculation unit of each time slave device is calculated based on the measurement information and offset information received for the first time from the device that the port determination unit has determined to receive the synchronization information from the time when the synchronization information is received. 6. The synchronization system according to claim 5, wherein a time after the delay time is calculated as a synchronization time.

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