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

Abstract

A time synchronization system (1000) comprises a synchronization management unit (10) and a synchronization management unit (20), each of which performs a time synchronization process based on an initial time from a specific clock source. The synchronization management unit (10) is connected to a network (100) and performs a time synchronization process with a general unit (11) contained in another communication device (2) connected via the network (100). The synchronization management unit (20) is connected to a network (200) different from the network (100) and performs a time synchronization process with general units (21, 22, 23) contained in yet another communication device (3, 4, 5) connected via the network (200).

Description

Technical area

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

[0002] In industrial control systems, a large number of communication devices are interconnected via a network. These networked communication devices synchronize the timing of their built-in clocks and can therefore achieve synchronized control of operations at the same input and output times (for example, patent literature 1).

[0003] For example, an industrial network based on CC-Link IE TSN (registered trademark) achieves network synchronization communication via a time synchronization function based on the IEEE 1588 protocol, defined in non-patent literature 1, or the IEEE 802.1AS protocol, defined in non-patent literature 2. The time synchronization function aligns the times of communication devices on the same network, thus providing identical input and output times.

[0004] In an industrial network with a time synchronization function based on a protocol such as IEEE 1588 or IEEE 802.1AS, a communication device acts as a synchronization management unit (CMU), which manages the reference time. Other communication devices, distinct from the CMU, act as common-order units (CEUs), which are managed by the CMU. Each CMU calculates a time difference between its own time and the CMU's time, based on a propagation delay between the CMU and the CMU, and then synchronizes its CMU time with the CMU's time.

[0005] The communication system disclosed in patent literature 1 comprises first and second communication devices in the same network, whose times are synchronized by a time synchronization function based on the propagation delay time, and several third communication devices connected to one of the communication devices via system buses. The first and second communication devices each perform the time synchronization function and repeatedly transmit the current time, which is the same for all communication devices in the same network, to each of the third communication devices connected to the first or second communication device via the system bus.Patent literature 1 describes that the time synchronization function can align the times of other communication devices, which are connected to one of the communication devices via system buses, to the time maintained by the communication devices in a single network. List of patent literature

[0006] Patent literature 1: International publication number WO 2020 / 194714 Non-patented literature Non-patent literature 1: IEEE Std. 1588-2008, “IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems” Non-Patent Literature 2: IEEE Std. 802.1AS-2020, “IEEE Standard for Local and Metropolitan Area Networks-Timing and Synchronization for Time-Sensitive Applications” Brief description of the invention: Technical problem

[0007] The time synchronization function, which is based on a protocol such as IEEE 1588 or IEEE 802.1AS, can only achieve time synchronization between communication devices on the same network. This function cannot synchronize the times of communication devices on different networks and is therefore not capable of cross-network synchronization control. The number of communication devices that can be connected to a single network is limited to the number of communication devices capable of synchronization control.

[0008] The communication system disclosed in patent literature 1, in which several communication devices in a single network synchronize their times with other communication devices connected to one of the communication devices via system buses, is not capable of time-synchronized control across networks. A technique for time-synchronized control between communication devices belonging to different networks is desired.

[0009] One objective of the present disclosure, which has been achieved in view of the above circumstances, is to provide a communication device, a time synchronization system, a time synchronization method and a program that can achieve time synchronization across networks. Solution to the problem

[0010] To achieve the above objective, a communication device, according to a first aspect of the present disclosure, comprises a first synchronization management unit and a second synchronization management unit, each configured to perform a time synchronization process based on a first time from a specific clock source. The first synchronization management unit is connected to a first network and performs a time synchronization process with a first general unit contained in another communication device, which is connected to the communication device via the first network.The second synchronization management unit is connected to a second network, which is different from the first network, and performs a time synchronization process with a second general unit, which is contained in yet another communication device that is connected to the communication device via the second network.

[0011] A communication device according to a second aspect of the present disclosure comprises a first general unit connected to a first network and a third synchronization management unit connected to a third network different from the first network. The first general unit performs a time synchronization process with a first synchronization management unit contained in a further communication device connected to the first communication device via the first network. The third synchronization management unit performs a time synchronization process, based on a second time synchronized by the first general unit, with a third general unit contained in yet another communication device connected to the communication device via the third network. Advantageous effects of the invention

[0012] According to the aspects of the present disclosure, multiple synchronization management units synchronize their times with general entities connected via different networks, or a synchronization management unit performs a time synchronization process with another general entity via a network different from the network containing the synchronization management unit with which a general entity synchronizes its time. This configuration can therefore achieve time synchronization across networks. Brief description of the drawings Fig. Figure 1 is a block diagram showing an exemplary overall configuration of a time synchronization system according to one embodiment; Fig. Figure 2 is a block diagram showing an example hardware configuration of a communication device; Fig. Figure 3 is a block diagram showing an example of a functional configuration of a communication device; Fig. Figure 4 is a block diagram showing an example of a functional configuration of another communication device; Fig. Figure 5 is a block diagram showing an exemplary functional configuration of yet another communication device; Fig. 6 is a flowchart showing time synchronization; Fig. Figure 7 is a flowchart showing a time synchronization process; Fig. 8 is a table showing exemplary times that are held by individual communication devices at several points in time; Fig. Figure 9 is a block diagram showing an exemplary overall configuration of a time synchronization system according to a modification; and Fig. Figure 10 is a block diagram showing an exemplary overall configuration of a time synchronization system according to a further modification. Description of embodiments / design form

[0013] The following describes in detail an embodiment of the present disclosure with reference to the accompanying drawings. In the drawings, components that are identical or corresponding to one another are designated with the same reference numeral.

[0014] Fig. Figure 1 is a block diagram showing an exemplary overall configuration of a time synchronization system 1000 according to one embodiment. The time synchronization system 1000 is an industrial control system that, for example, performs time-synchronized control. The time synchronization system 1000 comprises several networks and several communication devices that are connected to one of the networks. Although Fig. Figure 1 shows an exemplary configuration of the time synchronization system 1000, which includes networks 100, 200 and 300 and communication devices 1 to 8, which are connected to one of the networks. The configuration can have any number of networks, any number of communication devices and any number of connections.

[0015] The networks in this embodiment are each a closed network to which a limited number of communication devices can be connected. A typical example of such a network is one based on CC-Link IE TSN (registered trademark).

[0016] Communication device 1, which serves as the first communication device, is connected to the separate networks 100 and 200 and comprises a synchronization management unit 10 of network 100 and a synchronization management unit 20 of network 200. Synchronization management unit 10 is the first synchronization management unit, which manages a general unit 11 connected to network 100, which serves as the first network. Synchronization management unit 20 is the second synchronization management unit, which manages general units 21 to 23 connected to network 200, which serves as the second network. General unit 11 is the first general unit contained within communication device 2, which serves as the second communication device and is connected to communication device 1, which serves as the first communication device.The general units 21 to 23 are second general units contained in the communication devices 3 to 5, which serve as third communication devices connected to the communication device 1, which serves as the first communication device.

[0017] Communication device 2, which serves as the second communication device, is connected to network 100 and another network 300. It comprises a synchronization management unit 30 of network 300 and the general unit 11 of network 100. Synchronization management unit 30 is a third synchronization management unit that manages general units 31 to 33, which are connected to network 300, which serves as a third network. General units 31 to 33 are third general units contained within communication devices 6 to 8, which serve as third communication devices and are connected to communication device 2, which serves as the second communication device.

[0018] Fig. Figure 2 shows a hardware configuration of each of the communication devices 1 to 8. The communication devices 1 to 8 are each contained in a device, such as an actuator or a robot, to perform, for example, time-synchronized control in the industrial control system. As shown in Fig. As shown in Figure 2, the communication devices 1 to 8 each comprise a processor 901, a primary memory 902, a secondary memory 903, a clock generator 904, an input device 905, an output device 906, and a communication interface 907. The primary memory 902, the secondary memory 903, the clock generator 904, the input device 905, the output device 906, and the communication interface 907 are connected to the processor 901 via internal buses 908.

[0019] The 901 processor, for example, is a central processing unit (CPU). The 901 processor reads programs stored in the 903 secondary memory and executes them, thus achieving various functions of each of the communication devices 1 to 8.

[0020] Primary memory 902 is a working memory from which the processor 901 can quickly read data for various calculations, and to which the processor 901 can quickly write data for various calculations. A typical example of primary memory 902 is random access memory (RAM).

[0021] The secondary memory 903 stores programs for achieving various functions of each of the communication devices 1 through 8 and various types of data, including parameters used in processes of the processor 901. Examples of secondary memory 903 include non-volatile semiconductor memory such as electrically erasable programmable read-only memory (EEPROM) and flash memory, magnetic floppy disks, and optical discs. The secondary memory 903 provides data to the processor 901 for use by the processor 901 and stores data supplied by the processor 901 according to the processor 901's instructions.

[0022] The 904 clock generator comprises a clock generation circuit with an oscillating element. The 904 clock generator produces a clock signal according to the number of oscillations of the oscillating element and outputs the clock signal. A typical example of the oscillating element is a crystal oscillator. The clock signal contains clock pulses. For example, the number of rising edges of the clock pulses is counted by the 901 processor to determine the time.

[0023] The input device 905 comprises an input device, such as an input key or a pointing device. The input device 905 receives information entered by a user into each of the communication devices 1 to 8 and communicates the received information to the processor 901. The output device 906 comprises an output device, such as a display or a speaker. The output device 906 outputs various types of information to the user according to the instructions from the processor 901.

[0024] The 907 communication interface is a network interface for communication between communication devices 1 through 8 or for communication with other external devices. A typical example of the 907 communication interface follows the CC-Link IE TSN communication standard (registered trademark). The 907 communication interface receives signals from other devices and outputs the data specified by these signals to the 901 processor. Furthermore, the 907 communication interface transmits signals specifying data output by the 901 processor to other devices. Although Fig. Figure 2 shows a single communication interface 907 as a representative example; the communication devices 1 to 8 can each include two or more communication interfaces 907 for connecting to the individual networks.

[0025] The in Fig. The two hardware components shown work together, such that the communication devices 1 to 8 each comprise a memory unit, a synchronization management unit, and a general-purpose unit. In other words, the execution of the programs stored in the secondary memory 903 by the processor 901 causes the following in Fig. The two hardware components shown work together to perform the functions of the storage unit, the synchronization management unit, and the general unit.

[0026] Fig. Figures 3 to 5 are each a block diagram showing a functional configuration of communication devices 1 to 8. As in Fig. As shown in Figure 3, the communication device 1, which serves as the first communication device, comprises a storage unit 110, which stores time information 101, which indicates a first time of a specific clock generator based on clock signals from the clock generator 904, the synchronization management unit 10, which performs a time synchronization process with the general unit 11 of the communication device 2, which is connected to the network 100, and the synchronization management unit 20, which performs a time synchronization process with the general units 21 to 23 of the communication devices 3 to 5, which are connected to the network 200.

[0027] Synchronization management units 10 and 20 operate based on the time information 101, which is maintained by communication device 1. In the time synchronization system 1000, the first time specified by the time information 101 is used as the reference time for networks 100 and 200, to which communication device 1 is connected, and as the reference time for the entire time synchronization system 1000.

[0028] Synchronization Management Unit 10 comprises a synchronizer 111 (first synchronizer), which performs a time synchronization process, and a communicator 112, which communicates with the general unit 11. Synchronization Management Unit 20 comprises a synchronizer 211 (second synchronizer), which performs a time synchronization process, and a communicator 212, which communicates with general units 21 through 23. The time synchronization processes of synchronizers 111 and 211 are according to the IEEE 1558 protocol or the IEEE 802.1AS protocol.

[0029] As in Fig. As shown in Figure 4, the communication device 2, which serves as the second communication device, comprises a storage unit 210, which stores time information 201, which indicates a second time of another clock generator based on clock signals from the clock generator 904, the synchronization management unit 30, which performs a time synchronization process with the general units 31 to 33 of the communication devices 6 to 8, which are connected to the network 300, and the general unit 11, which is connected to the network 100 and whose time is synchronized by the synchronization management unit 10 of the communication device 1.

[0030] The time information 201 held by communication device 2 corresponds to a second time information, which indicates the second time that is synchronized to the time held by communication device 1 by the time synchronization process performed by the synchronization management unit 10 of communication device 1. In the time synchronization system 1000, the time information 201 is used as the reference time of network 300, which is connected to the synchronization management unit 30 contained in communication device 2.

[0031] General Unit 11 comprises a synchronizer 321 (third synchronizer), which performs a time synchronization process by communicating with the synchronization management unit 10 of the communication device 1, and a communicator 322, which communicates with the synchronization management unit 10. Synchronization management unit 30 comprises a synchronizer 311 (fourth synchronizer), which performs a time synchronization process, and a communicator 312, which communicates with General Units 31 to 33. The time synchronization processes of synchronizers 321 and 311 are according to the IEEE 1558 protocol or the IEEE 802.1AS protocol.

[0032] As in Fig. As shown in Figure 5, the communication devices 3 to 5, which serve as the third communication device without a synchronization management unit, each function as a storage unit 410, which stores time information 401 of another clock generator based on clock signals from the clock generator 904, and one of the general units 21 to 23, which are connected to the network 200 and whose time is synchronized by the synchronization management unit 20 of the communication device 1.

[0033] The same applies to communication devices 6 to 8, which serve as the third communication devices, connected to communication device 2, which serves as the second communication device. As in Fig. As shown in Figure 5, this means that the communication devices 6 to 8 each function as a storage unit 410, which stores time information 401 based on clock signals from the clock generator 904, and one of the general units 31 to 33, which are connected to the network 300 and whose time is synchronized by the synchronization management unit 30 of the communication device 2.

[0034] The time information 401 held by communication devices 3 to 5 indicates the time that is synchronized to the time held by communication device 1 by the time synchronization process performed by the synchronization management unit 20 of communication device 1. The time information 401 held by communication devices 6 to 8 indicates the time that is synchronized to the time held by communication device 2 by the time synchronization process performed by the synchronization management unit 30 of communication device 2. The general units 21 to 23 and 31 to 33, which are contained in communication devices 3 to 8, operate based on the time information 401.

[0035] General units 21 to 23 and 31 to 33 each comprise a synchronizer 421, which performs a time synchronization process by communicating with the synchronization management unit 20 of communication device 1 or the synchronization management unit 30 of communication device 2, and a communicator 422, which communicates with the synchronization management unit 20 or 30. The time synchronization process of the synchronizer 421 is according to the IEEE 1558 protocol or the IEEE 802.1AS protocol.

[0036] The following describes the operating modes of the time synchronization system 1000 with the configuration described above, with reference to the flowcharts of the Fig. 6 and Fig. 7. Fig. Figure 6 is a flowchart showing the time synchronization of the entire time synchronization system 1000, and Fig. Figure 7 is a flowchart showing the time synchronization process of each of the communication devices 1 to 8.

[0037] Time synchronization in the Time Synchronization System 1000 first comprises time synchronization processes based on the initial time information, executed by communication devices in the network. This network includes the first communication device, which in turn includes the first and second synchronization management units. As in Fig. As shown in Figure 6, this means that the synchronization management unit 10 of the communication device 1, which serves as the first communication device, performs a time synchronization process with the general unit 11 in the network 100, and the synchronization management unit 20 performs a time synchronization process with the general units 21 to 23 in the network 200 (step S101: first time synchronization step).

[0038] Time synchronization then comprises a time synchronization process based on the second time information, which specifies the time synchronized in step S101, and is executed by communication devices in the network that includes the third synchronization management unit, contained in the second communication device. This means that the synchronization management unit 30 of communication device 2 executes a time synchronization process with the general units 31 to 33 in network 300 (step S102: second time synchronization step).

[0039] As in Fig. As shown in Figure 7, processor 901 first determines in each of the communication devices 1 to 8 whether the communication device contains a general entity (step S201). If no general entity is contained (step S201: No), the process proceeds to step S204. Conversely, if a general entity is contained (step S201: Yes), the general entity waits unless an instruction to initiate time synchronization is received from the synchronization management unit that manages this general entity (step S202: No).

[0040] In particular, the general unit 11 of communication device 2 waits until it receives an instruction to initiate time synchronization from the synchronization management unit 10, the general units 21 to 23 of communication devices 3 to 5 wait until they receive an instruction to initiate time synchronization from the synchronization management unit 20, and the general units 31 to 33 of communication devices 6 to 8 wait until they receive an instruction to initiate time synchronization from the synchronization management unit 30.

[0041] When the general-purpose units 11, 21 to 23, and 31 to 33 of communication devices 2 to 8 each receive an instruction to initiate time synchronization from one of the synchronization management units 10, 20, and 30 (step S202: Yes), that general-purpose unit synchronizes its time with the synchronization management unit 10, 20, or 30 (step S203). This time synchronization process is in accordance with the IEEE 1558 protocol or the IEEE 802.1AS protocol. The time synchronization process aligns the times of communication devices 2 to 5 to the time held by communication device 1 and aligns the times of communication devices 6 to 8 to the time held by communication device 2.

[0042] The processor 901 of each of the communication devices 2 through 8 then determines whether the communication device contains a synchronization management unit (step S204). If no synchronization management unit is contained (step S204: No), the process terminates. If, on the other hand, a synchronization management unit is contained (step S204: Yes), the synchronization management unit performs a time synchronization process with the commons in the network containing the synchronization management unit (step S205), after which the time synchronization process terminates.

[0043] Specifically, the synchronization management unit 10 of communication device 1 performs a time synchronization process with the general unit 11 in network 100, and the synchronization management unit 20 performs a time synchronization process with the general units 21 to 23 in network 200. The synchronization management unit 30 of communication device 2 performs a time synchronization process with the general units 31 to 33 in network 300.

[0044] The communication device 1, which does not contain a general unit and contains the synchronization management units 10 and 20, achieves time synchronization in the networks 100 and 200 in step S205 of the Fig. 7 steps shown (step S101 in Fig. 6) The general unit 11 of the communication device 2 then synchronizes its time with the synchronization management unit 10 in step S203. The synchronization management unit 30 then achieves time synchronization in the network 300 (step S102 in Fig. 6).

[0045] The following describes an example of time synchronization with reference to Fig. 8. Fig. Figure 8 shows exemplary entities of time information, which are transmitted by the individual communication devices at various points in time. Fig. 6 will be held.

[0046] In Fig. In step 8, communication devices 1, 2, 3, 4, 5, 6, 7, and 8 maintain different times A, B, C, D, E, F, G, and H before the time synchronization processes. In step S101 in Fig. 6. The synchronization management unit 10 contained in the communication device 1 executes the time synchronization process with the general unit 11, which is connected via the network 100. This time synchronization process aligns the time held by the general unit 11 with the time held by the synchronization management unit 10.

[0047] In step S101 in Fig. 6. The synchronization management unit 20 contained in the communication device 1 executes the time synchronization process with the general units 21 to 23, which are connected via network 200. This time synchronization process aligns the times held by the general units 21 to 23 with the time held by the synchronization management unit 20. The time synchronization process in network 100 by the synchronization management unit 10 and the time synchronization process in network 200 by the synchronization management unit 20 can be executed in any order.

[0048] The time synchronization processes by synchronization management units 10 and 20 are based on the first time, which is specified by the identical time information 101. These time synchronization processes therefore align the time held by communication device 2, which is connected to network 100, and the times of communication devices 3, 4, and 5, which are connected to network 200, to the time A held by communication device 1, as Fig. 8 shows.

[0049] In step S102 in Fig. 6. The synchronization management unit 30 contained in communication device 2 executes the time synchronization process with the general units 31 to 33, which are connected via network 300. This time synchronization process aligns the times of the general units 31 to 33 with the time of the synchronization management unit 30. Due to the time synchronization process with communication device 1 in step S101, the time held by communication device 2 is equal to the time A held by communication device 1. This means that the time synchronization process by the synchronization management unit 30 in step S102 aligns the times held by the general units 31 to 33 with the time A held by the synchronization management unit 20.

[0050] Steps S101 and S102 therefore synchronize the times of all communication devices connected to networks 100, 200 and 300 to time A.

[0051] As described above, in the time synchronization system 1000 according to the embodiment, the synchronization management units 10 and 20 of the communication device 1 perform time synchronization processes with the general units 11 and 21 to 23, which are connected via networks 100 and 200, based on the time information 101, which specifies a time from the clock generator. The synchronization management unit 30 of the communication device 2, which contains the general unit 11, then performs a time synchronization process with the general units 31 to 33, which are connected via network 300, based on the time information 201, which specifies the synchronized time. These processes can achieve time synchronization across networks.

[0052] The hardware configurations and flowcharts in the embodiment described above are merely examples and can be varied and modified as desired. Although in the embodiment described above the communication device 1 contains the synchronization management units 10 and 20, the communication device 1 can, for example, contain three or more synchronization management units and effect time synchronization in three or more networks.

[0053] Although in the embodiment described above the communication devices 3 to 8 each contain the general unit, the communication device may also contain a synchronization management unit which synchronizes its time with a general unit of a communication device which is connected via another network.

[0054] Although the time synchronization system comprises the first communication device (communication device 1), which contains the synchronization management units 10 and 20, the second communication device (communication device 2), which contains the synchronization management unit 30 and the general unit 11, and the third communication devices (communication devices 3 to 8), which each contain only one of the general units 21 to 23 and 31 to 33 in the embodiment described above, this configuration is merely an example. Fig. 9 and Fig. Figure 10 is a block diagram showing an exemplary overall configuration of a time synchronization system according to a modification of the embodiment.

[0055] As in Fig. As shown in Figure 9, the time synchronization system can, for example, be without the second communication device and comprise the first communication device (communication device 1), which contains the synchronization management units 10 and 20, and third communication devices (communication devices 2 to 5), each containing one of the general units 11 and 21 to 23. As shown in Fig.As shown in Figure 10, the time synchronization system can alternatively consist of a communication device (communication device 9) containing only the synchronization management unit 10, a second communication device (communication device 2) containing the synchronization management unit 30 and the general unit 11, and third communication devices (communication devices 6 to 8), each containing one of the general units 31 to 33. Alternatively, the communication device (communication device 9) containing only the synchronization management unit 10 can be connected in series with second communication devices (communication devices 2), each containing the synchronization management unit 30 and the general unit 11.

[0056] Although in the embodiment described above, time synchronization between a synchronization management unit and a general unit is achieved by aligning the times to the first time held by communication device 1, this configuration is merely an example. Time synchronization can also be achieved by aligning the times to the time held by another communication device or to a third time. Alternatively, the synchronization management unit or the general unit of a communication device can achieve time synchronization by maintaining the difference between its own time and a specific time, without aligning its own time to that specific time.

[0057] The assignment of functions of processor 901 to each of the communication devices 1 to 8 in the embodiment described above is merely an example and can be modified as desired. The functions of processor 901 can be achieved not only by a dedicated system but also by a computer system with ordinary communication functions.

[0058] A program for achieving the functionality described above can be stored and distributed on non-volatile, computer-readable recording media, such as Compact Disc Read-Only Memories (CD-ROMs), Digital Versatile Discs (DVDs), magneto-optical (MO) disks, and memory cards. The program can then be installed on a computer, causing the computer to perform the functions. If the functions are achieved by sharing an operating system (OS) and an application, or by cooperation between the OS and the application, only the components distinct from the OS need to be stored on a non-volatile recording medium.

[0059] The foregoing describes some exemplary embodiments for illustrative purposes. Although the preceding discussion has presented specific embodiments, the person skilled in the art understands that changes in form and detail may be made without departing from the broader spirit and scope of the invention. Accordingly, the description and drawings are to be understood as exemplary rather than restrictive. This detailed description is therefore not to be understood in a limiting sense, and the scope of the invention is defined solely by the appended claims, together with the full range of equivalents attributable to such claims. Reference symbol list 1 to 9 Communication device 10, 20, 30 Synchronization Management Unit 11, 21, 22, 23, 31, 32, 33 General unit 100, 200, 300 network 101, 201, 401 Time information 110, 210, 410 storage unit 111, 211, 311, 321, 421 Synchronizers 112, 212, 312, 322, 422 Communicator 901 processor 902 Primary storage 903 Secondary storage 904 Clock generator 905 inputs 906 issuers 907 Communication interface 908 internal bus 1000 Time Synchronization System QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] WO 2020 / 194 714

[0006] Cited non-patent literature

[0000] IEEE Std. 1588-2008, „IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems

[0006] IEEE Std. 802.1AS-2020, „IEEE Standard for Local and Metropolitan Area Networks-Timing and Synchronization for Time-Sensitive Applications

[0006]

Claims

[1] Communication device, comprising: a first synchronization management unit; and a second synchronization management unit, wherein the first synchronization management unit and the second synchronization management unit are each configured to execute a time synchronization process based on a first time from a specific clock source, wherein the first synchronization management unit is connected to a first network and performs a time synchronization process with a first general unit, wherein the first general unit is contained in a further communication device which is connected to the communication device via the first network, and wherein the second synchronization management unit is connected to a second network, which is different from the first network, and performs a time synchronization process with a second general unit, wherein the second general unit is contained in a further communication device which is connected to the communication device via the second network. [2] Communication device according to claim 1, wherein the first synchronization management unit aligns a time of the first general unit to the first time, wherein the first general unit is connected to the first synchronization management unit via the first network, and wherein the second synchronization management unit aligns a time of the second general unit to the first time, wherein the second general unit is connected to the second synchronization management unit via the second network. [3] Communication device, comprising: a first general unit connected to a first network; and a third synchronization management unit, which is connected to a third network that is different from the first network, wherein the first general-purpose unit performs a time synchronization process with a first synchronization management unit, the first synchronization management unit being contained in a further communication device which is connected to the communication device via the first network, and wherein the third synchronization management unit performs a time synchronization process, based on a second time synchronized by the first general unit, with a third general unit, wherein the third general unit is contained in a further communication device which is connected to the communication device via the third network. [4] Communication device according to claim 3, wherein the first general unit aligns its time to a time of the first synchronization management unit, wherein the first synchronization management unit is connected to the first general unit via the first network, and wherein the third synchronization management unit aligns a time of the third general unit to the time which is aligned by the first general unit to the time of the first synchronization management unit, wherein the third general unit is connected to the third synchronization management unit via the third network. [5] Time synchronization system, comprising: at least one communication device according to claim 1 or 2 and the communication device according to claim 3 or 4. [6] Time synchronization methods, including: a first time synchronization step of the execution, by each of at least one first synchronization management unit contained in a communication device, of a time synchronization process based on a first time of a specific clock generator, with a general unit connected to the first synchronization management unit via a network; and a second time synchronization step of execution, by a third synchronization management unit, which is contained in yet another communication device, which contains the general unit, of a time synchronization process, which is based on a time synchronized in the first time synchronization step, with another general unit, which is connected to another network, which is different from the network to which the first synchronization management units are connected. [7] A program configured to cause a computer with communication capabilities to function as: a first synchronizer, which performs a time synchronization process based on a first time from a specific clock generator with another computer, wherein the other computer is connected to the computer via a first network and functions as a first generality; and a second synchronizer, which performs a time synchronization process based on the first time with yet another computer, the yet another computer being connected to the computer via a second network, which is different from the first network, and functioning as a second general entity. [8] A program configured to cause a computer with communication capabilities to function as: a third synchronizer, which performs a time synchronization process with another computer, wherein the other computer is connected to the computer via a first network and functions as a first synchronization management unit; and a fourth synchronizer, which performs a time synchronization process based on a time synchronized by the third synchronizer with yet another computer, wherein the yet another computer is connected to the computer via a third network, which is different from the first network, and functions as a third general entity.

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