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

Abstract

A time synchronization system (1) comprises a first time synchronization device (100), a second time synchronization device (200), a third time synchronization device (300) and a fourth time synchronization device (400), each of which performs time synchronization as a master station or as a device station.In the first time synchronization device (100), the second time synchronization device (200), the third time synchronization device (300), or the fourth time synchronization device (400), a master station determination module (122) determines, based on a parameter predetermined by a user, whether the time synchronization device performs control as the master station, and a time synchronization module (130) performs time synchronization as the master station when it is determined that the time synchronization device performs control as the master station, and performs time synchronization as the device station when it is determined that the time synchronization device does not perform control as the master station.

Description

Technical field

[0001] The present disclosure relates to a time synchronization system, a time synchronization apparatus, a time synchronization method, and a program. background

[0002] A time synchronization system for synchronizing time between devices in a network uses a standard such as IEEE 802.1AS or IEEE 1588 (IEEE: Institute of Electrical and Electronics Engineers). According to such a standard, the time synchronization system uses the Best Master Clock (BMCA) algorithm to select a Grand Master Clock (GMC), or grandmaster, which is a device that initially acts as a clock source.

[0003] The BMCA is an algorithm for a device to repeatedly compare priority information that the device comprises with priority information acquired from other devices to select a device with the highest priority among all devices in the network as the grandmaster or master station. As described in Fig. For example, as shown in Figure 9, each device performing the BMCA identifies the device as a master station when the devices are powered on at the start of the time synchronization system. Each device then sends an advertisement containing information including the priority information to the devices connected via the ports and compares the priorities of the other devices acquired after receiving the advertisements from the other devices with the priority of the device. Therefore, the devices with clock IDs 0x0003 and 0x0004, which have priorities 3 and 4 greater than 1 and 2, each identify the device as a device station. The devices with clock IDs 0x0001 and 0x0002, whose priorities are yet to be compared, send and receive the advertisements again among themselves to compare the priorities.The device with clock ID 0x0002 and priority 2 greater than 1 then identifies the device as a slave. The device with clock ID 0x0001 and priority 1 is then selected as the grandmaster.

[0004] As an example of such a time synchronization system, Patent Literature 1 describes a control system including switches and endpoints connected to a network, which perform BMCA to identify the grandmaster. In Patent Literature 1, the time synchronization accuracy index is calculated for a timer selected as a candidate for the grandmaster based on the time accuracy of the timer and the path index of the controller including the timer. Then, in Patent Literature 1, a timer with the highest accuracy index among multiple candidate timers is designated as the grandmaster, and priority setting information for setting the timer as the grandmaster is sent to the timer. Citation listPatent literature

[0005] Patent Literature 1: Unexamined Japanese Patent Application, Publication No. 2021-051652 Overview of the inventionTechnical problem

[0006] The control system described in Patent Literature 1 repeatedly calculates and compares the accuracy indexes to determine the grandmaster and perform the BMCA, and therefore may take a longer time to start the time synchronization control.

[0007] Under such circumstances, an object of the present disclosure is to shorten the time until the time synchronization control starts. Solution to the problem

[0008] To achieve the above-mentioned object, a time synchronization system according to one aspect of the present disclosure includes a plurality of time synchronization devices each performing time synchronization as a master station or as a device station connected to the master station to transmit and receive information to and from the master station.Each of the plurality of time synchronization devices includes a master station determination module for determining, based on a parameter predetermined by a user, whether the time synchronization device including the master station determination module performs control as the master station, and a time synchronization module for performing the time synchronization as the master station when it is determined that the time synchronization device including the master station determination module performs control as the master station, and for performing the time synchronization as the master station when it is determined that the time synchronization device including the master station determination module does not perform control as the master station. Advantageous effects of the invention

[0009] Each time synchronization device according to the above aspect of the present disclosure can determine whether the time synchronization device performs control as the master station based on the parameter predetermined by the user. Thus, in the time synchronization system according to the above aspect of the present disclosure, the user can predetermine a time synchronization device as the master station if the time synchronization device is identified in advance as being most suitable for the master station, without performing a master station selection algorithm such as the BMCA.Thus, the time synchronization system according to the above aspect of the present disclosure can determine the time synchronization device faster than a time synchronization system that performs an algorithm such as the BMCA to repeatedly compare information included in each time synchronization device to determine a time synchronization device most suitable for the master station to be the master station, and can thus shorten the time required before the start of the time synchronization control. Short description of the drawings Fig. 1 is a schematic diagram of an overall time synchronization system according to an embodiment; Fig. 2 is a functional block diagram of the time synchronization system; Fig. 3 is a block diagram of a time synchronization device showing the hardware configuration; Fig. 4A is a table showing an example display of parameter information; Fig. 4B is a table showing an example of displaying connection information; Fig. Figure 4C is a table showing an example of displaying port information; Fig. 5A is a diagram of an example of the time synchronization system in the power-on state; Fig. 5B is a timing diagram of a process setting process; Fig. 5C is a diagram of the example time synchronization system after the port setting process; Fig. 6 is a flowchart of a master station determination process; Fig. 7 is a flowchart of a port information determination process; Fig. 8 is a flowchart adapted from the flowchart in Fig. 7; and Fig. Figure 9 is a diagram describing a time synchronization system that performs the BMCA. Description of the embodiments

[0010] A time synchronization system, a time synchronization apparatus, a time synchronization method, and a program according to one or more embodiments of the present disclosure will be described in detail below with reference to the drawings. Like reference numerals denote like or corresponding components throughout the drawings. Time synchronization system according to an embodiment

[0011] A time synchronization system according to an embodiment of the present disclosure includes a plurality of time synchronization devices in a network, each operating as a master station or a device station, and synchronizes the time of the device station with the time of the master station. In the time synchronization system according to the present embodiment, the master station and the device station send and receive messages based on, for example, a standard such as IEEE 802.1AS or IEEE 1588 (IEEE: Institute of Electrical and Electronics Engineers). The device station calculates a propagation delay time for the messages to and from the master station and corrects the time to synchronize the time between the master station and the device station.The time synchronization system according to the present embodiment determines a grandmaster, or in other words, the master station, from the time synchronization devices at the start of the system, or more precisely, when the time synchronization devices are turned on.

[0012] As in Fig. 1, a time synchronization system 1 according to the present embodiment includes, as an example, time synchronization devices, a first time synchronization device 100, a second time synchronization device 200, a third time synchronization device 300, and a fourth time synchronization device 400. The first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 can send and receive information via a network 500. Time synchronization device according to embodiment

[0013] As in Fig. 2, the first time synchronization device 100 includes an information storage 110 that stores information, a Best Master Clock Algorithm (BMCA) determination module 121 that determines whether the first time synchronization device 100 performs the BMCA, a master station determination module 122 that determines whether the first time synchronization device 100 performs control as a master station, and a time synchronization module 130 that performs time synchronization as a master station or as a device station.The first time synchronization device 100 also includes an information transmitter 140 that transmits information to the device station when it is determined that the first time synchronization device 100 is performing control as the master station, and a response information reception module 150 that receives response information when the first time synchronization device 100 sends information to the device station as the master station. The first time synchronization device 100 also includes a configuration acquisition module 161 that acquires the configuration of the connection with the device station as the master station, and a port information determination module 162 that determines port information about the device station as the master station.The first time synchronization device 100 also includes an information receiving module 170 that receives information from the master station when it is determined that the first time synchronization device 100 performs control as a device station, a response information transmitter 180 that transmits the response information as a device station for the information sent from the master station, and a port setting module 190 that sets ports.

[0014] Similar to the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 each include the information storage 110, the BMCA determination module 121, the master station determination module 122, and the time synchronization module 130. Similar to the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 each include the information transmitter 140, the response information reception module 150, the configuration acquisition module 161, the port information determination module 162, the information reception module 170, the response information transmission module 180, and the port setting module 190. Hardware configuration of the time synchronization device according to the embodiment

[0015] As in Fig. 3, the first time synchronization device 100 includes, for example, a controller 51 that performs processes based on a control program 59. The controller 51 includes a central processing unit (CPU). The controller 51 functions, for example, as a BMCA determination module 121, a master station determination module 122, a time synchronization module 130, a configuration acquisition module 161, a port information determination module 162, and a port setting module 190, as shown in Fig. 2, based on control program 59. Referring to Figure 3, the first

[0016] Time synchronization device 100 has a main memory 52 into which the control program 59 is to be loaded. The main memory 52 is used as a work area for the controller 51. The main memory 52 includes a random access memory (RAM).

[0017] The first time synchronization device 100 includes an external memory 53 that prestores the control program 59. The external memory 53 provides information stored in the program to the controller 51 upon instruction from the controller 51 and stores information provided by the controller 51. The external memory 53 includes a non-volatile recording medium such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). The external memory 53 functions, for example, as the Fig. 2 shown information storage 110. Referring to Figure 3, the first

[0018] Time synchronization device 100 includes a user-operable operating device 54. Input data is provided to the controller 51 via the operating device 54. The operating device 54 includes input components such as a keyboard, a mouse, and a touchscreen.

[0019] The first time synchronization device 100 also includes a display 55 that displays information input via the operating device 54 and information output from the controller 51. The display 55 includes a display device such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display.

[0020] The first time synchronization device 100 also includes a transmission-reception module 56 that transmits and receives information. The transmission-reception module 56 includes an information communication device, such as a communication network termination device or a wireless communication device connected to a network. The transmission-reception module 56 functions, for example, as the time synchronization module 130, the information transmission module 140, the response information reception module 150, the information reception module 170, and the response information transmission module 180, as shown in Fig. 2 shown. With reference to Figure 3, in the first

[0021] Time synchronization device 100, the master memory 52, the external memory 53, the operating device 54, the display 55 and the transmission-reception module 56 are connected to the controller 51 via an internal bus 50.

[0022] The first time synchronization device 100 implements the functions of the information storage 110, the BMCA determination module 121, the master station determination module 122, the time synchronization module 130, the information transmitter 140, the response information reception module 150, the configuration acquisition module 161, the port information determination module 162, the information reception module 170, the response information transmission module 180, and the port setting module 190, as shown in Fig. 2, the controller 51 uses the master memory 52, the external memory 53, the operating device 54, the display 55, and the transmission-reception module 56 as resources. For example, the first time synchronization device 100 performs information storage with the information storage 110, BMCA determination with the BMCA determination module 121, and master station determination with the master station determination module 122. For example, the first time synchronization device 100 performs time synchronization with the time synchronization module 130, information transmission with the information transmitter 140, reception of response information with the response information reception module 150, configuration acquisition with the configuration acquisition module 161, and port information determination with the port information determination module 162.For example, the first time synchronization device 100 performs information reception with the information reception module 170, response information transmission with the response information transmission module 180, and port setting with the port setting module 190.

[0023] The second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 each include the same hardware configuration as the first time synchronization device 100. More specifically, the same hardware configuration as above applies to the second time synchronization device 200, in which the first time synchronization device 100 is replaced by the second time synchronization device 200, to the third time synchronization device 300, in which the first time synchronization device 100 is replaced by the third time synchronization device 300, and to the fourth time synchronization device 400, in which the first time synchronization device 100 is replaced by the fourth time synchronization device 400.Therefore, the hardware configurations of the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 are not described in detail to avoid redundancy.

[0024] Details of the functional configuration of the time synchronization device according to the embodiment Referring to Fig. 2, the information storage 110 stores several types of information. For example, the information storage 110 stores parameter information indicating user-specified parameters, connection information about the connection to other time synchronization devices, priority information indicating the priority of the device including the information storage 110 in executing the BMCA, and clock ID information indicating a clock ID of the device including the information storage 110.

[0025] The parameter information is based on an input by the user using the operating device 54 and can be in the form of a Fig. 4A. More specifically, the parameter information includes a BMCA (user setting) item that indicates whether to perform BMCA, a GM (user setting) item that indicates whether to operate as a master station when BMCA is not performed, and values of the items. For example, the parameter information indicates that BMCA (user setting) is OFF and GM (user setting) is ON. The value of BMCA (user setting) in the parameter information must be ON for all time synchronization devices or OFF for all time synchronization devices. The value of GM (user setting) in the parameter information must be ON for each time synchronization device and OFF for all remaining time synchronization devices.

[0026] The connection information is determined by each time synchronization device and can be displayed in the form of a table, as in Fig. 4B. More specifically, the connection information includes information that can identify all ports of each device station, information that can identify the port to which each port is connected, and information that can identify the hop count of each port from the master station. For example, the connection information indicates that a first port is connected to a first port 0x0001 with hop count 1, and a second port is connected to a second port 0x0002 with hop count 3. The priority information is set by each time synchronization device to identify, for example, priority 3. The clock ID information is set by each time synchronization device to identify, for example, clock ID 0x0003.

[0027] The BMCA determination module 121 refers to the parameter information stored in the information storage 110 after the device is turned on, and determines that the time synchronization device performs the BMCA when the BMCA (user setting) is ON, and determines that the time synchronization device does not perform the BMCA when the BMCA (user setting) is OFF.

[0028] When the BMCA determination module 121 determines that the time synchronization device including the BMCA determination module 121 performs BMCA, the master station determination module 122 performs BMCA to determine whether the time synchronization device including the master station determination module 122 performs control as a master station. When the BMCA determination module 121 determines that the time synchronization device including the BMCA determination module 121 does not perform BMCA, the master station determination module 122 refers to the parameter information stored in the information storage 110.The master station determination module 122 then determines that the time synchronization device including the master station determination module 122 performs control as a master station when the GM (user setting) is ON, and determines that the time synchronization device performs control as a device station when the GM (user setting) is OFF.

[0029] In an example, as in Fig. As shown in Figure 5A, the time synchronization system 1 includes the time synchronization devices connected in a ring topology and has an initial setting that causes one of the time synchronization devices to assume control as the master station when the time synchronization devices are turned on. In this case, if the BMCA (user setting) is OFF and the GM (user setting) is ON in the parameter information in the first time synchronization device 100, the first time synchronization device 100 determines to perform control as the master station. In this case, the BMCA (user setting) and the GM (user setting) are turned off in the parameter information in the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400.The second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 thus determine to perform the control as the device stations.

[0030] The time synchronization module 130 performs a time operation as a master station when the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs the control as a master station, and performs the time operation as a device station when the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs the control as a device station.

[0031] The configuration acquisition module 161 acquires the connection configuration with the device stations when the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs control as the master station. The configuration acquisition module 161 first causes the information transmitter 140 to transmit a configuration acquisition frame, which is an example of information requesting information used to acquire the connection configuration, to all device stations. In the present embodiment, the information used to acquire the configuration includes the connection information, the priority information, and the clock ID information.The configuration acquisition module 161 then acquires the response information for the configuration acquisition frame received from the response information receiving module 150 from each device station. Based on the acquired response information, the configuration acquisition module 161 identifies the connection topology of the master station and the device stations, such as a bus, star, or ring topology, to acquire the connection configuration.

[0032] Thus, in the manner described above, Fig. 5A, the first time synchronization device 100, which is the master station, transmits the configuration acquisition frame to the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400, which are the device stations, and receives as response information the connection information, the priority information, and the clock ID information about each device station, as shown in Fig. 5B. The first time synchronization device 100 then detects the connection configuration based on the connection information. More specifically, the first time synchronization device 100 identifies the first port of the first time synchronization device 100 and the second port of the third time synchronization device 300 as connected to each other, and the second port of the first time synchronization device 100 and the first port of the fourth time synchronization device 400 as connected to each other. The first time synchronization device 100 also identifies the first port of the second time synchronization device 200 and the second port of the fourth time synchronization device 400 as connected to each other, and the second port of the second time synchronization device 200 and the first port of the third time synchronization device 300 as connected to each other.The first time synchronization device 100 can thus identify the time synchronization devices as being connected in a ring topology.

[0033] The port information determination module 162 determines the port information about the device stations based on the response information acquired by the configuration acquisition module 161. The port information determination module 162 first determines whether the master station and the device stations are connected in a ring topology based on the acquisition results of the configuration acquisition module 161. If the devices are not connected in a ring topology, but in a bus or star topology, for example, the port information determination module 162 designates the ports that receive information from the master station as slave ports, and the remaining ports that do not receive information from the master station as master ports.

[0034] When the devices are connected in a ring topology, the port information determination module 162 identifies, for each device, the hop count of each port from the master station based on the connection information. The port information determination module 162 also determines, for each device station having ports with different hop counts, the port with a smaller hop count as the slave port and the port with a larger hop count as the master port. The port information determination module 162 also compares, for each device station having ports with the same hop count, the clock ID values of the device stations connected to the respective ports identified from the clock ID information, and determines the port connected to the device station with a smaller clock ID value as the slave port and the port connected to the device station with a larger clock ID value as the passive port.

[0035] The port information determination module 162 then generates the port information indicating the roles of the identified ports of each slave to determine the port information. The port information is set by the master station and can be displayed in the form of a table, as shown in Fig. 4C. Specifically, the port information includes information that can identify all ports and the roles of the ports for each device station. For example, the port information indicates that the first port of the device station with clock ID 0x0002 is the passive port and the second port is the slave port.

[0036] When the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs control as a master station, the port setting module 190 sets all ports of the time synchronization device as master ports. When the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs control as a device station, the port setting module 190 sets each port of the time synchronization device to one of the master port, the slave port, or the passive port based on the port information received from the information receiving module 170.

[0037] As in Fig. As shown in Figure 5B, when the master station determination module 122 determines that the time synchronization device including the master station determination module 122 is performing control as the master station, the information transmitter 140 transmits the configuration acquisition frame to all device stations, and the response information reception module 150 receives, as response information, the information used to acquire the configuration held by each device station. When the port information determination module 162 determines the port information, the information transmitter 140, as an example of a port information transmitter, transmits the port information to all device stations, and the response information reception module 150 receives, as response information, information indicating the completion of the port setting by each device station.

[0038] When the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs control as the device station, the information receiving module 170 receives the configuration acquisition frame from the master station, and the response information transmitter 180 transmits the information used to acquire the configuration as response information. The information receiving module 170, as an example of a port information receiving module, receives the port information from the master station, and when the port setting module 190 sets each port, the response information transmitter 180 transmits the information indicating the completion of the port setting as response information.

[0039] Thus, identified in the Fig. 5A, as described above, the first time synchronization device 100, which is the master station, identifies the time synchronization devices as being connected in a ring topology based on the detection results described above, and identifies the hop counts of the ports of the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400, which device stations are based on the connection information.More specifically, the first time synchronization device 100 identifies the second time synchronization device 200 as having the first port and the second port each with the hop count of 2, the third time synchronization device 300 as having the first port with the hop count of 2 and the second port with the hop count of 1, and the fourth time synchronization device 400 as having the first port with the hop count of 1 and the second port with the hop count of 3.

[0040] The first time synchronization device 100 also determines the roles of the ports of the third time synchronization device 300 and the fourth time synchronization device 400, each having ports with different hop counts. Specifically, the first time synchronization device 100 determines that the first port of the third time synchronization device 300 is the master port and the second port is the slave port, and that the first port of the fourth time synchronization device 400 is the slave port and the second port is the master port. The first time synchronization device 100 also determines the roles of the ports of the second time synchronization device 200, which have ports with the same hop count.Specifically, the first time synchronization device 100 determines that the first port of the second time synchronization device 200 connected to the fourth time synchronization device 400 with a larger clock ID value of 0x0004 is the passive port, and the second port of the second time synchronization device 200 connected to the third time synchronization device 300 with a smaller clock ID value of 0x0003 is the slave port. The first time synchronization device 100 can thus generate the port information indicating the designated roles of the ports of the device stations.

[0041] As in Fig. 5B, the first time synchronization device 100 then sends the generated port information to the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400, and receives, as response information, the information indicating the completion of the port setting from each device station. As shown in Fig. 5C, the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 can thus determine the roles of the ports.

[0042] Flowchart of the master station determination process in the present embodiment The operation of each time synchronization device for determining whether to perform control as a master station will now be described with reference to the flowchart shown in Fig. 6. After power-up, each time synchronization device begins performing a Fig. 6 shown master station determination process. As in Fig. As shown in Figure 6, after the time synchronization device including the BMCA determination module 121 is turned on, the BMCA determination module 121 first refers to the parameter information stored in the information storage 110 and determines whether the BMCA (user setting) is ON (step S101). If the BMCA (user setting) is ON (Yes in step S101), the BMCA determination module 121 determines that the time synchronization device including the BMCA determination module 121 is performing the BMCA. The master station determination module 122 performs the BMCA (step S102) and determines whether the time synchronization device including the master station determination module 122 is selected as the master station (step S103).

[0043] If the BMCA (user setting) is OFF (No in step S101), the BMCA determination module 121 determines that the time synchronization device including the BMCA determination module 121 is not performing the BMCA. The master station determination module 122 refers to the parameter information stored in the information storage 110 and determines whether the GM (user setting) is ON (step S104). If the time synchronization device including the master station determination module 122 is selected as the master station (Yes in step S103) or if the GM (user setting) is ON (Yes in step S104), the master station determination module 122 determines that the time synchronization device including the master station determination module 122 is performing control as the master station. The time synchronization module 130 performs the time operation as the master station (step S105) and ends the process.If the time synchronization device is not selected as the master station (No in step S103) or if the GM (user setting) is OFF (No in step S104), the master station determination module 122 determines that the time synchronization device performs control as the device station. The time synchronization module 130 performs the time operation as the device station (step S106) and ends the process.

[0044] Flowchart of the method for determining the port information in the present embodiment The operation of the master station for determining the port information about the device stations will now be described with reference to the flowchart shown in the Fig. 7 and Fig. 8. When the master station determination module 122 determines that the time synchronization device including the master station determination module 122 performs control as a master station, the time synchronization devices each start a port information determination process shown in the Fig. 7 and Fig. 8. As shown in Fig. As shown in Figure 7, the configuration acquisition module 161 first causes the information transmitter 140 to transmit the configuration acquisition frame to all device stations (step S201), and the response information reception module 150 acquires the response information received from each device station (step S202). The configuration acquisition module 161 acquires the connection configuration based on the response information (step S203).

[0045] The port information determination module 162 then determines, based on the detection results of the configuration detection module 161, whether the master station and the device stations are connected in a ring topology (step S204). If the devices are not connected in a ring topology (No in step S204), the port information determination module 162 selects the device stations in ascending order of the clock ID value based on the clock ID information (step S205). The port information determination module 162 then designates, for each selected device station, the port that receives information from the master station as the slave port and the remaining port that does not receive information from the master station as the master port (step S206). The port information determination module 162 then determines whether all device stations have been selected (step S207).If not all device stations have been selected (No in step S207), the port information determination module 162 returns to step S205 and repeats the processing in steps S205 and S206 until all device stations are selected.

[0046] If the devices are connected in a ring topology (Yes in step S204), the port information determination module 162 selects the device stations in ascending order of the clock ID value, as shown in Fig.8 (step S208). The port information determination module 162 then identifies, for each selected device, the hop count of each port based on the connection information (step S209) and determines whether the hop counts of the ports are the same (step S210). If the hop counts vary (No in step S210), the port information determination module 162 designates, for the selected device station, the port with a smaller hop count as the slave port and the port with a larger hop count as the master port (step S211).If the hop numbers are the same (Yes in step S210), the port information determination module 162 compares the clock ID values of the device stations adjacent to the respective ports identified based on the clock ID information, and determines the port connected to the device station with a smaller ID value as the slave port and the port connected to the device station with a larger ID value as the passive port (step S212).

[0047] After determining the roles of the ports of the selected device stations in steps S211 and S212, the port information determination module 162 determines whether all device stations have been selected (step S213). If not all device stations have been selected (No in step S213), the port information determination module 162 returns to step S208 and repeats the processing in steps S208 to S212 until all device stations are selected. After determining the roles of the ports of the selected device stations in step S207 or S213, the port information determination module 162 generates the port information (step S214) and causes the information transmitter 140 to transmit the port information to all device stations (step S215). The response information reception module 150 acquires the response information received from each device station (step S216) and terminates the process.

[0048] As described above, in the time synchronization system 1 according to the present embodiment, the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 each include the master station determination module 122, which can determine, based on the parameter predetermined by the user, whether the time synchronization device including the master station determination module 122 performs control as the master station. If the master station determination module 122 determines that the time synchronization module performs control as the master station, the time synchronization module 130 performs time synchronization as the master station.When the master station determination module 122 determines that the time synchronization device does not perform control as the master station, the time synchronization device 130 performs time synchronization as the device station.

[0049] Thus, in the time synchronization system 1 according to the present embodiment, the user can predetermine a time synchronization device as the master station when, for example, a time synchronization device as a server functioning as a management station is pre-identified and the user intends the pre-identified time synchronization device to perform time synchronization as the master station. In other words, in the time synchronization system 1 according to the present embodiment, the user can predetermine a time synchronization device as the master station when the time synchronization device is pre-identified as the most suitable for the master station, without executing a master station selection algorithm such as the BMCA.Thus, the time synchronization system 1 according to the present embodiment can determine the time synchronization device as the master station faster than a time synchronization system that performs an algorithm such as the BMCA to repeatedly compare information held by each time synchronization device to determine a time synchronization device most suitable for the master station as the master station, and can thus shorten the time required before starting the time synchronization control.

[0050] In the time synchronization system 1 according to the present embodiment, when the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, or the fourth time synchronization device 400 performs time synchronization as the master station, the configuration acquisition module 161 acquires the connection configuration with the device stations. In this case, the port information determination module 162 determines the port information about the device stations based on the acquired configuration, and the information transmitter 140, as an example of the port information transmitter, transmits the determined port information to the device stations.When the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, or the fourth time synchronization device 400 performs the time synchronization as a device station, the information receiving module 170, as an example of the port information receiving module, receives the port information, and the port setting module 190 sets the port based on the port information.

[0051] Thus, in the time synchronization system 1 according to the present embodiment, the master station can determine the port information about the device stations and cause the device stations to set the ports. The time synchronization system 1 according to the present embodiment can thus set the ports of each device station faster than a time synchronization system in which each device station determines the port information and sets the ports of the device station, and can thus shorten the time required before starting the time synchronization control.

[0052] In the time synchronization system 1 according to the present embodiment, the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 each include the BMCA determination module 121, which determines whether the time synchronization device performs the BMCA based on the parameter predetermined by the user. If the time synchronization device is determined to perform the BMCA, the master station determination module 122 performs the BMCA to determine whether the time synchronization device performs control as the master station. If the time synchronization device is determined not to perform the BMCA, the master station determination module 122 determines whether the time synchronization device performs control as the master station based on the parameter.

[0053] Thus, in the time synchronization system 1 according to the present embodiment, the user can predetermine whether to perform the BMCA. For example, in the time synchronization system 1 according to the present embodiment, the BMCA may be performed to determine the master station when a time synchronization device to function as the management station is not identified in advance, and a time synchronization device most suitable for the master station among all the time synchronization devices is to be determined using the time before the start of the time synchronization control. In other words, in the time synchronization system 1 according to the present embodiment, the user can execute the BMCA to select the master station when a time synchronization device most suitable for the master station is not identified in advance. Variations

[0054] In the present embodiment, the parameters predetermined by the user are stored in each time synchronization device as parameter information in the information storage 110, and the time synchronization device refers to the stored parameter information. However, the parameter information may be stored in other ways. For example, the parameter information may be stored in a database server other than the time synchronization device, and the time synchronization device may refer to the parameter information stored in the database server. In this case, the database server may be a server in the time synchronization system 1 or an external device on the network.

[0055] In the present embodiment, the master station sends the configuration acquisition frame to all device stations and receives, as response information from each device station, the information used to acquire the connection configuration. However, the information may be received in other ways. For example, the device station may send the information used to acquire the connection configuration to the master station when it, as a device station, specifies the execution of time synchronization. This allows the master station to acquire the information used to acquire the connection configuration without sending the configuration acquisition frame.

[0056] As in the present embodiment, each time synchronization device can determine whether to perform BMCA based on the parameter predetermined by the user. However, the time synchronization device can perform the determination in different ways. For example, the BMCA (user setting) may be eliminated from the parameter information, and each time synchronization device can always determine whether to perform control as the master station without performing BMCA based on a parameter predetermined by the user.

[0057] The master operation sections of the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400, each including the controller 51, the master memory 52, the external memory 53, the operation device 54, the display 55, and the transmission-reception module 56, which are connected to each other via the internal bus 50, may be implemented by a common computer system instead of a dedicated system.For example, a computer program for performing the above operation may be stored in a non-volatile computer-readable recording medium such as a flash memory or a read-only memory of a digital versatile disc (DVD-ROM), distributed, and installed in a computer to implement the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 that perform the above-mentioned processes. The computer program may be stored in a storage device in a server in a communication network such as the Internet and downloaded to a conventional computer system to implement the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400.

[0058] When the functions of the first time synchronization device 100, the second time synchronization device 200, the third time synchronization device 300, and the fourth time synchronization device 400 are implemented partly by an operating system (OS) and partly by an application program, or by cooperation between the OS and the application program, parts of the application program alone may be stored in a non-volatile recording medium or storage device.

[0059] The computer program may be superimposed on a carrier wave provided over a communications network. For example, the computer program may be provided on a bulletin board system (BBS) in a communications network provided over the network. The operation described above can be performed by activating the computer program and executing the program in the same manner as other application programs under the control of the operating system.

[0060] The foregoing describes some example embodiments for illustrative purposes. Although specific embodiments have been presented in the foregoing discussion, those skilled in the art will recognize that changes in form and detail may be made without departing from the general spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention will be defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. List of reference symbols 1 time synchronization system 50 internal bus 51 Control 52 main memory 53 external storage 54 Operating device 55 Advertisement 56 Transmission-receiving module 59 Control program 100 first time synchronization device 110 Information storage 121 BMCA determination module 122 Master station determination module 130 Time synchronization module 140 Information transmission module 150 Response information receiving module 161 Configuration Capture Module 162 port information determination module 170 Information reception module 180 Response information sending module 190 Port settings module 200 second time synchronization device 300 third time synchronization device 400 fourth time synchronization device 500 Network QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-051652

[0005]

Claims

[1] Time synchronization system comprising: a plurality of time synchronization devices each performing time synchronization as a master station or a device station connected to the master station to send and receive information to and from the master station, wherein each of the plurality of time synchronization devices comprises: a master station determination module for determining, based on a parameter predetermined by a user, whether the time synchronization device having the master station determination module performs control as the master station, and a time synchronization module for performing time synchronization as the master station when it is determined that the time synchronization device having the master station determination module performs control as the master station, and for performing time synchronization as the device station when it is determined that the time synchronization device having the master station determination module does not perform control as the master station. [2] Time synchronization system according to claim 1, where the master station comprises: a configuration acquisition module to acquire a connection configuration with the device station, a port information determination module for determining port information about the device station based on the acquired configuration, and a port information transmission module for transmitting the determined port information to the device station, and wherein the device station comprises: a port information receiving module to receive the port information, and a port setting module to set a port based on the port information. [3] Time synchronization system according to claim 1 or 2, wherein each of the plurality of time synchronization devices further comprises a BMCA determination module for determining, based on the parameter, whether the time synchronization device comprising the BMCA determination module performs a BMCA, and where the BMCA is a best master clock algorithm, and wherein the master station determination module performs the BMCA to determine whether the time synchronization device including the master station determination module performs control as the master station when it is determined that the BMCA is to be performed, and to determine, based on the parameter, whether the time synchronization device including the master station determination module performs control as the master station when it is determined that the BMCA is not to be performed. [4] A time synchronization device for performing time synchronization as a master station or as a device station connected to the master station to send and receive information to and from the master station, the time synchronization device comprising: a master station determination module for determining, based on a parameter predetermined by a user, whether the time synchronization device performs control as the master station; and a time synchronization module for performing time synchronization as the master station when it is determined that the time synchronization device performs control as the master station, and for performing time synchronization as the device station when it is determined that the time synchronization device does not perform control as the master station. [5] Time synchronization method comprising: Determining with a computer, based on a parameter predetermined by a user, whether the computer performs control as a master station in a time synchronization system; and Performing time synchronization with the computer as the master station when it is determined that the computer is performing control as the master station, and Performing time synchronization with the computer as a device station in the time synchronization system when it is determined that the computer does not perform control as the master station. [6] A program for causing a computer to act as: a master station determination module for determining, based on a parameter predetermined by a user, whether the computer performs control as a master station in a time synchronization system; and a time synchronization module for performing time synchronization as a master station when it is determined that the computer performs control as the master station, and for performing time synchronization as a device station in the time synchronization system when it is determined that the computer does not perform control as the master station.

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