JP5183528B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system having a mesh network structure.

  In recent years, systems that perform environmental measurement, monitoring, control, and the like using wireless communication are increasing. In a wireless communication system that performs environmental measurement, monitoring, control, and the like, there are many cases where the target area is relatively wide or there are many obstacles for wireless communication in the target area. In such a case, in order to cover the target area, even if it is not possible to communicate directly depending on the environment such as the installation position of the receiver and the transmitter and the radio wave condition, it is possible to perform communication by relaying other devices. It is advantageous to use a communication network.

  As this type of wireless communication network, a mesh network such as a wireless communication network using a Zigbee (registered trademark) protocol (see, for example, Patent Documents 1 and 2) has been proposed. In this mesh network, bidirectional communication between a master node (master device) and a slave node (slave device) is performed by relaying other slave nodes in the direct communication range, and one communication path is multi- Even if communication is not possible due to the influence of path fading, the technology can search for another communication path and continue communication. Multipath fading refers to a phenomenon in which a received radio wave is canceled due to a phase difference generated between a plurality of communication radio wave reflection paths, and reception becomes impossible.

  In Patent Literature 3, there are two methods for establishing a communication path in a mesh network: a method of establishing from the master node side to each slave node and a method of establishing from each slave node side to the master node. A method is defined.

  When establishing a communication path from the master node side to the slave node, a route search is performed from the master node to the slave node. As a result of this route search success, a downlink from the master node to the slave node is established, and an uplink from the slave node to the master node is established accordingly.

  When establishing a communication path from the slave node side to the master node, a route search is performed from the slave node to the master node. As a result of this route search success, an uplink from the slave node to the master node is established, and a downlink from the master node to the slave node is established accordingly.

JP 2006-5928 A JP 2006-42370 A JP 2008-211684 A

  For example, in a monitoring / control system for industrial use such as air conditioning control, the system restarts due to the occurrence of several planned power outages and instantaneous power failures. At this time, the restart of the system is required to be completed in a time as fast as possible after the power recovery. In such a case, in the monitoring / control system using the conventional mesh network described above, it takes time to complete the establishment of the communication path between the master node and all the slave nodes, or the communication load on the master node There were problems such as concentration.

  Hereinafter, this problem will be described separately for a case where a communication path is established from the slave node side to the master node and a case where a communication path is established from the master node side to the slave node.

[When establishing a communication path from the slave node side to the master node (route search by uplink)]
In a monitoring / control system, the power supply system of all slave nodes is often shared. In such a case, all the slave nodes are activated simultaneously with the power recovery, and the route search is started. The route search from the slave node is performed by broadcasting. For this reason, communication collisions frequently occur due to the start of route search from all slave nodes, and the possibility of failure in route search becomes very high. As a result, the time required until the establishment of the communication path between the master node and all the slave nodes is finally increased.

[When establishing a communication path from the master node to the slave node (route search by downlink)]
Since the master node controls all communication timings, no communication collision occurs, and the establishment of the communication path is completed in the shortest time. However, since the route search does not always succeed, it is necessary to repeat the route search retry for the slave node that has failed in the route search, that is, the slave node that has failed to establish the communication path. On the other hand, since the slave node that has succeeded in the route search and has established the communication path starts communication with the master node, the communication load is always concentrated on the master node.

  If there is a slave node that is in a situation where route search is likely to fail due to deterioration of radio wave conditions, or a slave node that previously existed but does not exist at the time of power recovery, repeat the route search retry for that slave node. Therefore, a processing load for retry of route search is further applied to the master node that originally has a high communication processing load, and the communication performance of the entire system is deteriorated. In particular, when a slave node that no longer exists remains, such an unnecessary communication load is permanently generated.

  The present invention has been made to solve such problems, and the object of the present invention is to establish a mesh network in a time as fast as possible while avoiding concentration of communication load on the master device when the system is restarted. An object of the present invention is to provide a wireless communication system that can be increased.

  In order to achieve such an object, according to the present invention, a device located at the highest level is set as a master device, a device located at a lower level having the same power supply as the master device is set as a slave device, and the master device and the slave device are In a wireless communication system that performs two-way wireless communication along a communication path established by successful route search, the master device is Immediately after starting up, a master side route search means is provided that sequentially searches the slave device from the first device to the last device one by one, and the slave devices are numbered in order from the first for each slave device. Identifier storage means for storing the unique identifier n, and the master device Communication route establishment confirmation means for confirming whether or not a communication route with the master device has been established at the time when the route search from the first device to the last device in the network is completed, and this communication route establishment confirmation means When it is confirmed that the communication path with the master device has not been established, the identifier n is read from the identifier storage means, T is set to a predetermined time longer than the time required for route search, and the last device is changed from the first device to the last device. The number of devices up to M is M, and (“self identifier n” −1) × T time has elapsed from that point, starting from the time point of M × T time period until the master device succeeds in route search. Slave side route search means is provided.

  According to the present invention, when a power failure or a momentary power failure occurs, the common power supply to the master device and the slave device is cut off, and when the cut off power supply is restored and the system restarts, the master device Immediately after starting, the route search is sequentially performed once for each slave device from the head device to the last device. Here, assuming that the time for one route search is N and the number of devices from the first device to the last device is M, after the lapse of N × M time from the start of the master device, all the slave devices from the master device to Route search (route search from the master side) is completed.

  On the other hand, the slave device confirms whether or not a communication path with the master device has been established when N × M time has passed immediately after starting up itself. Here, if the communication path with the master device has not been established, (“self identifier n” −1) × T time has elapsed, and the master device is cycled to M × T time from the starting point. Until the route search (route search from the slave side) is successful. For example, when the self identifier n is 2, immediately after the start of the self, the route search is performed for the master device when (2-1) × T = T time has passed after N × M time has passed. Do. If this route search is not successful, the route search is performed again for the master device when M × T time has passed. Such a route search is repeated until it succeeds in the M × T time period.

  In this case, the slave device for which the communication path with the master device has not been established is immediately after starting itself, after N × M time has elapsed, and (“own identifier n” −1) × T time has elapsed. As a starting point, the route search is repeated for the master device with a period of M × T time. Therefore, even if there are a plurality of slave devices for which the communication path to the master device is not established, the route search for the master device is performed. There is no overlap. Also, since the master device searches for a route for the slave device only for N × M time immediately after its startup, even if there is a route search from the slave device after N × M time has passed, Will not concentrate.

  In the present invention, the number M of devices from the first device to the last device may be the number of slave devices actually registered in the master device, and the maximum number of slave devices that can be registered in the master device. It is good. In the present invention, the slave device can immediately start communication with the master device when the communication path is established by route search from the master device. It is desirable to wait until the route search from the first device to the last device is completed and to start communication with the master device, and to occupy the entire communication band for the route search from the master device.

  According to the present invention, when the time for one route search is N and the number of devices from the first device to the last device is M, all N.M times from the start of the master device are When the route search to the slave device (route search from the master side) is completed and N × M time has elapsed from the completion of the route search from the master side, the communication path with the master device is established. The slave device that has not been started searches for the route to the master device at a cycle of M × T time (route search from the slave side), starting from the time when “(self identifier n) −1” × T time has elapsed. ) Until the network is restarted, the mesh network can be set up in a time as fast as possible while avoiding concentration of communication load on the master device when the system is restarted. It is possible.

It is a block diagram which shows the outline of one Embodiment of the radio | wireless communications system which concerns on this invention. It is a figure which illustrates the maximum slave node number M on the system used by this radio | wireless communications system, the execution required time N of route search, and the execution time interval T of route search from the slave node SL side. It is a flowchart for demonstrating the route search function (master side route search function) which the master node in this radio | wireless system has. It is a flowchart for demonstrating the route search function (slave side route search function) which the slave node has in this radio | wireless system. It is a figure which shows the mode of the route search from the master side. It is a figure which illustrates the state after the route search from the master side is completed. It is a time chart which shows the 1st time of the route search from the master side, and the route search from the slave side. It is a figure which shows the mode of the 1st time of the route search from the slave side. It is a figure which illustrates the state after the 1st time of the route search from a slave side is completed. It is a figure which shows the mode of the 2nd time of the route search from a slave side. It is a figure which illustrates the state after the 2nd time of the route search from a slave side is completed. It is a time chart which shows the 2nd time of the route search from the slave side. It is a functional block diagram of the principal part of a master node. It is a functional block diagram of the principal part of a slave node.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of an embodiment of a radio communication system according to the present invention. In the figure, MS is a master node (master device) positioned at the highest level, and SL is a slave node (slave device) positioned at a lower level sharing the power source with the master node MS. The master node MS and slave node SL A mesh network is configured.

  In this embodiment, the maximum number of slave nodes SL that can be registered in the master node MS (the maximum number of slave nodes in the system) M and the route search are stored in the memories of the master node MS and the slave node SL. N (time required for execution of route search) N and execution time interval T of route search from the slave node SL are stored. In this example, the maximum number of slave nodes M on the system is 10, the execution time N for route search is 5 seconds, and the execution time interval T for route search from the slave node SL is 15 seconds (FIG. 2). reference).

  The memory of the slave node SL stores a unique identifier n assigned so as not to overlap in order from the first for each slave node SL. In the memory of the master node MS, the configuration of the slave node SL existing on the system is registered by a unique identifier n assigned to the slave node SL. In this example, as slave nodes existing in the system, identifier 1 of slave node SL1, identifier 2 of slave node SL2, identifier 3 of slave node SL3, identifier 4 of slave node SL4, identifier 9 of slave node SL9, and slave node The identifier 10 of SL10 is registered.

  FIG. 1 shows a state immediately after the power supply (common power supply) to the master node MS and the slave node SL is cut off due to the occurrence of a power failure or a momentary power failure, and the cut off power supply is restored and the system is restarted. Is shown. The slave node SL9 is registered in the master node MS, but is in a state where communication is not possible (communication impossible) due to a failure or the like, for example. Further, when the interrupted power supply is restored (when power failure occurs), the master node MS and all the slave nodes SL are activated all at once.

  The master node MS and the slave node SL are realized by hardware including a processor and a storage device, and a program for realizing various functions in cooperation with these hardware, and a route search function as a function unique to the present embodiment. have. Hereinafter, the route search function (master side route search function) of the master node MS will be described according to the flowchart shown in FIG. 3, and the route search function (slave side route search function) of the slave node SL will be described according to the flowchart shown in FIG. To do.

[Route search from the master side (route search by downlink)]
When the system is restarted, the master node MS performs a route search for the slave node L from the first slave to the last slave one by one, immediately after starting itself. In this case, depending on the maximum number of slave nodes M in the system, the number of target slaves is M = 10, the slave node with identifier 1 is the first slave, and the slave node with identifier 10 is the last slave.

  First, the master node MS sets the slave node with the identifier 1 as the first slave, that is, sets the slave node with the identifier 1 as the first target slave (FIG. 3: step S101), and the slave in which the target slave with the identifier 1 exists in the system. It is checked whether or not it is registered as a node (step S102). In this case, since the target slave with the identifier 1 is registered as the slave node SL1 (YES in step S102), a route search to the slave node SL1 is executed (step S103). This route search takes N = 5 seconds.

  After confirming that the target slave that has performed the route search is not the final slave (NO in step S104), 1 is added to the identifier 1 of the current target slave, and the identifier of the next target slave is set to identifier 2. (Step S105), it is checked whether or not the target slave of the identifier 2 is registered as a slave node existing on the system (Step S102). In this case, since the target slave with the identifier 2 is registered as the slave node SL2 (YES in step S102), a route search to the slave node SL2 is executed (step S103). This route search takes N = 5 seconds.

  Similarly, the route search to the registered slave nodes SL3 and SL4 is executed by repeating steps S102 to S105 in the same manner. After the route search to the slave node SL4 is executed, the identifier of the target slave is set to the identifier 5. In this case, the target slave having the identifier 5 is not registered as a slave node existing on the system. Therefore, the master node MS does not perform the route search for the target slave with the identifier 5 (NO in step S102), and waits for the time required for executing the route search N = 5 seconds (YES in step S106). The process proceeds to steps S104 and S105.

  Thereby, the identifier of the next target slave is set to the identifier 6 (step S105), and the process returns to step S102. In this case, since the target slave with the identifier 6 is not registered as a slave node existing in the system, the route search is not performed for the target slave with the identifier 6 (NO in step S102), and the route search needs to be executed. After the elapse of time N = 5 seconds (YES in step S106), the process proceeds to steps S104 and S105. In the same manner, the route search is not performed for the target slaves of the identifiers 7 and 8 that are not registered as slave nodes existing in the system, and only the elapsed time for executing the route search N = 5 seconds. , The process of proceeding to steps S104 and S105 is repeated.

  Next, when the identifier of the target slave is the identifier 9, since the target slave of the identifier 9 is registered as the slave node SL9 (YES in step S102), a route search to the slave node SL9 is executed (step S102). S103). Even when the identifier of the target slave is the identifier 10, since the target slave of this identifier 10 is registered as the slave node SL10 (YES in step S102), the route search to the slave node SL10 is executed (step S102). S103). In this case, since the target slave of the identifier 10 is the final slave (YES in step S104), a series of route searches (route search from the master side) is terminated.

  FIG. 5 shows the route search from the master side described above. In this case, when the system is restarted, the route search for the slave node SL1 is executed immediately after (after 0 seconds). Then, after the time required for executing the route search N = 5 seconds, the route search for the slave node SL2 is executed, and further after 10 seconds after N = 5 seconds, the route search for the slave node SL3 is executed, and further N = 5 15 seconds after the second, a route search for the slave node SL4 is executed.

  Further, after 20 seconds after N = 5 seconds, the target slave is not registered, so the route search is not executed, and the passage of N = 5 seconds is awaited. Since the target slave is not registered after 25 seconds waiting for N = 5 seconds, 30 seconds waiting for N = 5 seconds, and 35 seconds waiting for N = 5 seconds, the route is not registered. The search is not executed and N = 5 seconds are awaited. Then, 40 seconds after the passage of N = 5 seconds, the route search for the slave node SL9 is executed, and further, after 45 seconds after N = 5 seconds, the route search for the slave node SL10 is executed. As a result, the route search from the master side is completed 50 seconds after the system is restarted.

  As described above, in this embodiment, when the required time N for route search is 5 seconds and the maximum number of slave nodes M on the system is 10, N × M = 5 seconds × 10 after the system is restarted. The route search from the master side is completed in 50 seconds. Until this route search is completed, the slave node SL waits for acceptance of a route search from the master node MS (FIG. 4: step S201), and when a route search from the master node MS is accepted (YES in step S202). , A notification that the route search is accepted is sent to the master node MS. Upon receiving this notification, the master node MS determines that the route search is successful. Thereby, a communication path (downlink and uplink) between the master node MS and the slave node SL is established.

  Note that the slave node SL in which the communication path is established by the route search from the master side does not start communication until the route search from the master side is completed. That is, in the present embodiment, the slave node SL can immediately start communication with the master node MS when the communication path is established by route search from the master node MS. Wait until the route search from the side is completed, start communication with the master node MS, and occupy the entire communication band for route search from the master node MS. This avoids concentration of communication load during route search from the master side, and shortens the time for route search from the master side.

  In addition, in order to avoid duplication of the timing of starting the route search from the slave side, which will be described later, the route search from the master side does not overlap with the maximum number of slave nodes M even if there are no maximum number of slave nodes M. There is a period of minutes. In this example, there is no slave node with the identifiers 5 to 8, and therefore the allocation time for the route search for the slave nodes with the identifiers 5 to 8 is originally unnecessary (the 20th to 40th seconds). There is no such thing as shortening the route search period from the side.

  FIG. 6 illustrates a state after the route search from the master side is completed. In this example, the route search is successful for the slave nodes SL1, SL2, and SL3, and between the master node MS and the slave node SL1, between the master node MS and the slave node SL2, and between the master node MS and the slave node SL3. A communication path between them has been established. On the other hand, the route search fails for the slave nodes SL4, SL9, and SL10, and the communication path between the master node MS and the slave nodes SL4, SL9, and SL10 is not established. At this point, N × M = 5 seconds × 10 units = 50 seconds have elapsed since the system was restarted.

  FIG. 7 shows a time chart in this case. Time t1 is the time when the system is restarted (simultaneous power recovery), and the route search from the master side is performed from time t1 to time t2 until 50 seconds elapse. At time t2, the route search from the master side is completed, and the route search is not retried for the slave nodes SL4, SL9, and SL10 that have failed in the route search.

  When the route search from the master side is completed, normal communication is started between the slave nodes SL1, SL2, SL3 and the master node MS, which have been successfully route-searched and the communication path has been established. The communication load is concentrated. On the other hand, in the route search, the communication load is most concentrated on the issuer. Therefore, if the route search is retried by the master node MS, the communication load is further applied to the master node MS, and the performance of normal communication is reduced. End up.

  For this reason, after the route search from the master side is completed, the route search is not retried even if there is a slave node that has failed in the route search. Further, especially when there is a slave node that is registered but is not actually communicable like the slave node SL9, the route search retry for this slave node is prevented from being executed permanently. It is also for the purpose.

[Route search from slave side (route search by uplink)]
When the system is restarted, the slave node SL immediately after starting itself, N (required time for route search) × M (maximum number of slave nodes) = 5 seconds × 10 = 50 seconds Without doing anything, the route search from the master side is executed, and the communication path is established (FIG. 4: steps S201 to S203).

  If N × M = 50 seconds have elapsed without establishment of a communication path (YES in step S203), the slave node SL determines that a communication path with the master node MS has not been established, and stores it in the memory. The stored self identifier is read (step S204). That is, the slave node SL confirms whether or not a communication path with the master node MS has been established immediately after starting itself, and when the route search from the master side is completed. When it is confirmed that the communication path is not established, the self identifier stored in the memory is read out.

  In the example shown in FIG. 6, when the route search from the master side is completed, communication paths are established between the slave nodes SL1, SL2, and SL3 and the master node MS, but the slave nodes SL4 and SL10 A communication path has not been established with the master node MS. Therefore, the slave node SL4 reads its own identifier 4, and the slave node SL10 reads its own identifier 10.

  Then, the slave node SL4 obtains the route search start time from itself as the time when (“self identifier 4” −1) × T time has passed (step S205). Here, T is an execution time interval of route search from the slave node SL side, and T = 15 seconds is defined in this embodiment. Therefore, the slave node SL4 sets the time when (4-1) × T = 3 × 15 = 45 seconds have elapsed since the completion of the route search from the master side as the route search start time from itself.

  Similarly, the slave node SL10 obtains the route search start time from itself as the time when ("own identifier 10" -1) × T time has elapsed (step S205), and when the route search from the master side is completed. The time when (10-1) × T = 9 × 15 = 135 seconds has elapsed is set as the route search start time from itself.

  Then, the slave nodes SL4 and SL10 execute the route search to the master node MS (step S207) when the current time reaches the route search time from itself (YES in step S206), and the route search succeeds. If YES (YES in step S208), the processing is terminated assuming that a communication path with the master node MS has been established.

  If the route search fails (NO in step S208), the next route search start time is determined as the time when M × T time has elapsed from the previous route search start time (step S209). Here, M is the maximum number of slave nodes on the system, and M = 10 is determined in the present embodiment. Therefore, when the route search fails, the previous route search time is set as the starting point, and the time when 10 × T = 150 seconds elapses is set as the next route search start time.

  FIG. 8 shows the route search from the slave side described above. In this case, when the system restarts and N × M = 50 seconds elapses, when 45 seconds elapses, the slave node SL4 executes a route search for the master node MS. Further, after a system restart occurs and N × M = 50 seconds elapses, when 135 seconds elapses, the slave node SL10 executes a route search for the master node MS. Note that the slave nodes SL1, SL2, SL3, and SL do not execute route search because the communication path is established. Since there are no slave nodes with identifiers 5, 6, 7, 8, and 9, nothing is done.

  In this embodiment, the route search execution time interval T from the slave node SL side is set to be longer than the time N required for route search (required route search execution time) N. In this example, T = 15 seconds and N = 5 seconds. This is because the slave node SL and the master node MS, which have completed the establishment of the communication path, may perform normal communication after that, and it is necessary to leave a certain communication band so as not to hinder their communication. is there.

  FIG. 9 shows the state after the first route search from the slave side is finished (when N × M = 50 seconds have passed after the system restart has occurred and M × T = 150 seconds have passed). Illustrate. In this example, the route search of the slave node SL10 succeeds, and the communication path between the master node MS and the slave node SL10 is established, but the route search of the slave node SL4 fails, and the master node MS and the slave node SL4 The communication path between is not established.

  FIG. 7 also shows a time chart in this case. Time t1 is the time when system restart occurs (simultaneous power recovery), time t2 is the time when N × M = 50 seconds have passed, 45 seconds after this N × M = 50 seconds have passed The route search for the master node MS from the slave node SL4 is executed at the time (time t3) after the elapse, and the route search for the master node MS from the slave node SL10 is executed when the time of 135 seconds elapses (time t4). . In this case, the route search at time t3 has failed, and the route search at time t4 has succeeded. Then, when M × T = 150 seconds have elapsed (time t5), the first route search from the slave side is completed.

  In this case, when the first route search from the slave side is completed, only the slave node SL4 remains without successful route search. For this reason, the second route search from the slave side is performed. In the second route search from the slave side, the slave node SL4 executes a route search for the master node MS when M × T time has elapsed from the previous route search start time. That is, if the first point of the route search from the slave side is started, the route search (retry) for the master node MS is executed when 45 seconds have elapsed from that point (see FIG. 10).

  FIG. 11 illustrates a state after the second route search from the slave side is completed. In this example, the route search of the slave node SL4 is successful (see FIG. 12), and the communication path between the master node MS and the slave node SL4 is established. As a result, communication paths between all the slave nodes SL and the master node MS that actually exist on the system are established, and the startup of the system is completed.

  In this example, it is assumed that the route search of the slave node SL4 has succeeded in the second route search from the slave side. However, if the route search of the slave node SL4 fails, the route from the slave side is similarly determined. A third route search is performed, and the retry is repeated until the route search is successful in an M × T time period starting from the previous route search start time.

  As described above, in this embodiment, when the system is restarted, the mesh network can be started up in a time as fast as possible while avoiding concentration of communication load on the master node MS.

  FIG. 13 shows a functional block diagram of the main part of the master node MS. The master node MS has a maximum slave node number storage unit 1A for storing the maximum number of slave nodes SL that can be registered with itself (the maximum number of slave nodes on the system) M, and a slave with an identifier 1 immediately after its startup. A master side route search unit 1B that sequentially performs a route search from the first slave to the last slave one by one with a node as a head slave and a slave node with an identifier M as a final slave.

  FIG. 14 shows a functional block diagram of the main part of the slave node SL. The slave node SL has an identifier storage unit 2A for storing a unique identifier n assigned in order from the first for each slave node SL, and the maximum number of slave nodes SL that can be registered in the master node MS ( Maximum slave node number storage unit 2B for storing the maximum number of slave nodes on the system) M, route search execution required time storage unit 2C for storing time required for route search (route search execution required time) N, and slave A route search execution time interval storage unit 2D that stores a route search execution time interval T from the node SL side, a communication path establishment confirmation unit 2E, and a slave side route search unit 2F are provided.

  In this slave node SL, the communication path establishment confirmation unit 2E receives the master at the time when N × M time has elapsed immediately after its activation (when the route search from the first node to the last node in the master node MS is completed). It is confirmed whether a communication path with the node MS is established. When the communication route establishment confirmation unit 2E confirms that the communication route with the master node MS has not been established, the slave side route search unit 2F reads its own identifier n from the identifier storage unit 2A, From (“self identifier n” −1) × T time has passed as a starting point until a route search is successfully performed for the master node MS in a cycle of M × T time.

  In the embodiment described above, the number M of nodes from the first node to the last node in the master node MS is the maximum number of slave nodes SL that can be registered in the master node MS. The number of slave nodes SL that are actually registered may be used.

  The wireless communication system of the present invention can be used in various fields such as a medium-scale and large-scale monitoring control system having a mesh network structure in which a communication trunk line is wireless. Specifically, it can be applied to a room air conditioning system by VAV (variable air volume adjustment).

  MS ... master node, SL (SL1, SL2, SL3, SL4, SL9, SL10) ... slave node, 1A ... maximum slave node number storage unit, 1B ... master side route search unit, 2A ... identifier storage unit, 2B ... maximum slave Node number storage unit, 2C ... route search execution time storage unit, 2D ... route search execution time interval storage unit, 2E ... communication path establishment confirmation unit, 2F ... slave side route search unit.

Claims (4)

The device located at the highest level is set as a master device, the device located at a lower level common to this master device and the power source is set as a slave device, and another slave device is set as a relay point between the master device and the slave device. In a wireless communication system that performs a route search for a communication route and performs bidirectional wireless communication along a communication route established by the success of this route search,
The master device is
Immediately after starting itself, the slave device is provided with means for sequentially performing the route search once from the head device to the last device,
The slave device is
Identifier storage means for storing a unique identifier n assigned in order from the first for each slave device;
Communication path establishment confirmation means for confirming whether or not a communication path with the master device has been established at the time when the route search from the first device to the last device in the master device is completed immediately after starting the device itself. When,
When it is confirmed by the communication path establishment confirmation means that a communication path with the master device is not established, the identifier n is read from the identifier storage means, and a predetermined time longer than the time required for the route search is obtained. The time is T, the number of devices from the first device to the last device is M, and (“self identifier n” −1) × T time has elapsed from that point in time at a cycle of M × T time. A wireless communication system, comprising: slave side route search means for performing the route search on the master device until the route search is successful. The wireless communication system according to claim 1, wherein
The wireless communication system, wherein the number M of devices from the first device to the last device is the number of slave devices actually registered in the master device. The wireless communication system according to claim 1, wherein
The wireless communication system, wherein the number M of devices from the first device to the last device is the maximum number of slave devices that can be registered in the master device. In the radio | wireless communications system described in any one of Claims 1-3,
The slave device is
When it is confirmed by the communication path establishment confirmation means that a communication path with the master device has been established, communication with the master device is started from that point. .

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