JP6178540B1 - Wireless communication system and sensor - Google Patents

Abstract

The data station 10 communicates with a plurality of repeaters 20 according to a communication schedule divided into a plurality of time slots. Each of the plurality of repeaters 20 is assigned a specific slot among the plurality of time slots. The communication schedule includes an emergency slot in addition to the specific slot. Each of the plurality of repeaters 20 communicates with the data station 10 in the specific slot, and can communicate with the data station 10 in the emergency slot.

Description

  The technology disclosed herein relates to a wireless communication system and a communication terminal.

  Conventionally, a wireless communication system in which a network is formed by a plurality of communication terminals is known.

  For example, the wireless communication system described in Patent Literature 1 includes one communication terminal serving as a parent device and a plurality of communication terminals serving as child devices that communicate with the parent device. Each child device is assigned a specific time slot, and the parent device communicates with each child device in a corresponding time slot.

Japanese Patent Laid-Open No. 6-232835

  By the way, in the wireless communication system as described above, the parent device and the child device do not communicate except in the corresponding time slot. In normal processing, there is no particular problem even if communication is performed at such timing. However, if it is necessary to communicate between the master unit and the slave unit, communication cannot be performed until the corresponding time slot arrives. It takes time to do it.

  The technology disclosed herein has been made in view of the above points, and its purpose is to realize early communication with a communication terminal serving as a parent device when communication is required. It is in.

  The technique disclosed here is intended for a wireless communication system in which a network is formed by a plurality of communication terminals. The plurality of communication terminals include a master unit and a plurality of slave units, and the master unit communicates with the plurality of slave units according to a communication schedule divided into a plurality of time slots, and the plurality of slave units Each of the machines is assigned a specific time slot of the plurality of time slots, and the communication schedule includes an emergency time commonly assigned to the plurality of slave machines in addition to the specific time slot. Each of the plurality of slave units includes a slot, and communicates with the master unit in the specific time slot, but can communicate with the master unit in the emergency time slot.

  The communication terminal disclosed here communicates with other communication terminals. The communication terminal is assigned a specific time slot in a communication schedule divided into a plurality of time slots, and communicates with other communication terminals in the specific time slot. Communication with other communication terminals is possible in the time slot.

  Moreover, the communication terminal disclosed here communicates with other communication terminals. The communication terminal includes a sensor unit that detects a predetermined physical quantity, and a processing unit that transmits a detection value of the sensor unit to another communication terminal. The processing unit is a communication schedule divided into a plurality of time slots. When it is necessary to transmit the detection value at a timing other than the specific time slot while transmitting the detection value at the specific time slot to another communication terminal to which the specific time slot is allocated The detected value is transmitted to the other communication terminal in an emergency time slot among the plurality of time slots.

  According to the wireless communication system, when communication is required, communication with a communication terminal serving as a parent device can be realized at an early stage.

  Further, according to the communication terminal, when communication is required, communication with the communication terminal serving as a parent device can be realized at an early stage.

FIG. 1 is a schematic diagram of a wireless communication system. FIG. 2 is a block diagram of the data station. FIG. 3 is a block diagram of the repeater. FIG. 4 is a block diagram of the sensor. FIG. 5 is a diagram showing a communication schedule. FIG. 6 is a functional block diagram of the repeater. FIG. 7 is a functional block diagram of the sensor. FIG. 8 is a flowchart showing the processing of the repeater. FIG. 9 is a flowchart illustrating processing of the sensor in the first mode. FIG. 10 is a flowchart illustrating processing of the sensor in the second mode. FIG. 11 is a diagram illustrating a frame configuration. FIG. 12 is a flowchart illustrating processing of the sensor in the second mode according to the second embodiment.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

Embodiment 1
FIG. 1 is a schematic diagram of a wireless communication system 100. The wireless communication system 100 includes a data station 10, a plurality of relay devices 20, and a plurality of sensors 30. The data station 10, the repeater 20, and the sensor 30 are communication terminals that perform wireless communication with each other and autonomously construct a network. In the wireless communication system 100, a multi-hop wireless network is formed. The data station 10 functions as a parent device, and the relay device 20 functions as a child device. Basically, the data station 10 communicates with the relay machine 20, and the sensor 30 communicates with the relay machine 20. The data station 10 and the repeater 20 have a tree-type network topology with the data station 10 as a vertex. In the present specification, in the network, the data station 10 side is the upstream side or the upper side, and the end side of the tree is the downstream side or the lower side. Further, when the data station 10, the repeater 20, and the sensor 30 are not distinguished, they may be simply referred to as communication terminals. In addition, when distinguishing each relay machine 20, an alphabet is added after the reference numeral “20”.

  In the wireless communication system 100, the sensor 30 detects a predetermined physical quantity, and the detected value, that is, the detected data is collected in the data station 10 via the relay device 20. In the example in the present disclosure, the wireless communication system 100 is installed in a factory having a steam system. The steam system has a plurality of steam traps T (only one is shown in FIG. 1). The sensor 30 detects the frequency and temperature of the steam trap T.

<Data station configuration>
FIG. 2 is a block diagram of the data station 10. The data station 10 establishes a communication path of the wireless communication system 100 and collects and manages detection data of the sensor 30. Although not shown, the data station 10 is connected to an upper server or the like via an external network or the like. The data station 10 transfers the detection data of the sensor 30 to a server or the like as necessary.

  The data station 10 includes a CPU 11, a memory 12, a storage unit 13, a wireless communication circuit 14, a timing circuit 15, a higher level interface unit 16, and a power supply circuit 17.

  The storage unit 13 stores various programs and various information. The CPU 11 performs various processes by reading and executing various programs from the storage unit 13. For example, the storage unit 13 defines a program for forming a network communication path, a program for collecting detection data of the sensor 30, tree information on the network communication path, and a schedule for communicating with the repeater 20. Schedule information, collected detection data, and the like are stored.

  The wireless communication circuit 14 performs wireless communication with other communication terminals such as the repeater 20. The wireless communication circuit 14 operates under the control of the CPU 11, converts various signals into wireless signals by processing such as encoding and modulation, and transmits the signals via an antenna. In addition, the wireless communication circuit 14 converts a signal received via the antenna into an appropriate signal by processing such as demodulation / combination.

  The clock circuit 15 generates a predetermined clock and clocks the time serving as the reference for the data station 10. The upper interface unit 16 performs interface processing with a server or the like. The power supply circuit 17 is connected to an external power supply (not shown) and supplies power to each element of the data station 10.

<Configuration of repeater>
FIG. 3 is a block diagram of the repeater 20. The relay machine 20 transmits the detection data of the sensor 30 to the data station 10 in response to a command from the data station 10.

  The repeater 20 includes a CPU 21, a memory 22, a storage unit 23, a wireless communication circuit 24, a timer circuit 25, a power supply circuit 26, and a battery 27.

  The storage unit 23 stores various programs and various information. The CPU 21 performs various processes by reading and executing various programs from the storage unit 23. For example, in the storage unit 23, a program for forming a network communication path, a program for relaying detection data of the sensor 30, information on upper and lower communication terminals, detection data acquired from the sensor 30, and the like Is remembered.

  The wireless communication circuit 24 performs wireless communication with other communication terminals. The wireless communication circuit 24 operates under the control of the CPU 21, converts various signals into wireless signals through processing such as encoding and modulation, and transmits the signals via an antenna. The wireless communication circuit 24 converts the signal received via the antenna into an appropriate signal by processing such as demodulation and decoding.

  The clock circuit 25 generates a predetermined clock and clocks a time that is a reference for the repeater 20. A battery 27 is connected to the power circuit 26. The power supply circuit 26 supplies power to each element of the repeater 20.

<Sensor configuration>
FIG. 4 is a block diagram of the sensor 30. The sensor 30 detects the frequency and temperature of the steam trap T and transmits the detected data to the corresponding relay device 20. The sensor 30 includes a sensor unit 40 that detects a predetermined physical quantity, and a processing unit 50 that transmits a detection value of the sensor unit 40 to another communication terminal.

  The sensor unit 40 includes a vibration sensor and a temperature sensor, and detects the vibration frequency and temperature of the steam trap T. The sensor unit 40 is installed so as to be in contact with the casing of the steam trap T (for example, an inflow portion into which steam and drain flow), and detects the frequency and temperature of the contacted portion. The sensor unit 40 outputs an electrical signal corresponding to the detected frequency and temperature to the processing unit 50.

  The processing unit 50 includes a CPU 51, a memory 52, a storage unit 53, a wireless communication circuit 54, a timing circuit 55, a sensor interface unit 56, a power supply circuit 57, and a battery 58.

  The storage unit 53 stores various programs and various information. The CPU 51 performs various processes by reading and executing various programs from the storage unit 53. For example, in the storage unit 53, a program for forming a communication path of the network, a program for acquiring the vibration frequency and temperature from the sensor unit 40, and transmitting them to the relay device 20 as detection data, the detected vibration frequency and temperature Is stored, a program for determining whether or not is within a predetermined range, information on a higher-level communication terminal, detection data, and the like.

  The wireless communication circuit 54 performs wireless communication with other communication terminals. The wireless communication circuit 54 operates under the control of the CPU 51, converts various signals into wireless signals by processing such as encoding and modulation, and transmits the signals via an antenna. The wireless communication circuit 54 converts the signal received via the antenna into an appropriate signal by processing such as demodulation / compositing.

  The timer circuit 55 generates a predetermined clock and measures the time that is the reference of the sensor 30. The sensor interface unit 56 performs interface processing with the sensor unit 40. A battery 58 is connected to the power supply circuit 57. The power supply circuit 57 supplies power to each element of the sensor 30.

<Communication schedule>
The wireless communication system 100 configured as described above collects the detection data of the sensor 30 in the data station 10 as a normal driving operation. The data station 10 communicates with each relay device 20 according to the communication schedule shown in FIG. 5 and collects detection data of the sensor 30 corresponding to each relay device 20, that is, connected.

  The communication schedule of FIG. 5 shows one cycle of data collection, and the communication schedule of FIG. 5 is repeatedly executed. The communication schedule is divided into a plurality of time slots. Each repeater 20 is assigned a specific time slot. Each repeater 20 communicates with the data station 10 in the corresponding time slot, and transmits detection data from the sensor 30 connected to the repeater 20 to the data station 10 (hereinafter, this process is also referred to as “reply process”). Say). Basically, each repeater 20 is in an active state in a specific time slot assigned (hereinafter also referred to as “specific slot”), and is in a sleep state in other than a specific slot. However, since the relay device 20 existing on the communication path between the other relay device 20 and the data station 10 needs to perform relay processing when the lower-order relay device 20 communicates with the data station 10, The time slot assigned to the machine 20 (hereinafter also referred to as “relay slot”) becomes active and relay processing is executed. Further, since the sensor 30 transmits detection data to the relay device 20 in a specific slot of the connected relay device 20, the sensor 30 is in an active state in the specific slot of the relay device 20. The sensor 30 is basically in a sleep state when it is not necessary to transmit detection data to the relay device 20.

  In the communication schedule of FIG. 5, time slots are defined in a matrix. Time slots are assigned according to the hierarchy of communication paths in a tree structure. Specifically, a tree structure hierarchy is assigned to each column. For example, the data station 10 is assigned to the column L0, the first layer (ie, the number of hops is 1) is assigned to the column L1, and the second layer (ie, the number of hops is 2) is assigned to the column L2. Is assigned. The same applies to the third and subsequent layers.

  Normally, any one time slot is assigned to each repeater 20. The time slot of the column L1 is allocated to the first layer relay devices 20a and 20j. The second slot relay units 20b, 20c, 20d, and 20k are assigned the time slot of the column L2. The time slot of the column L3 is allocated to the relay devices 20e, 20f, and 20g in the third layer. The time slots in the column L4 are allocated to the fourth-layer repeaters 20h and 20i. On the other hand, since the data station 10 has more processing content than the repeater 20, a plurality of time slots (all time slots in the row L0 in FIG. 5) are assigned to the data station 10 instead of one time slot. . In addition, since the number of time slots included in the column is different from the number of repeaters 20 included in each layer (usually, the number of time slots included in the column is larger), the time slots included in the column include There are some relays that are not assigned.

  Further, as described above, in a specific slot of a certain repeater 20, the sensor 30 connected to the repeater 20 is also in an active state, and therefore, a specific time slot is virtually assigned to each sensor 30 as well. It will be. However, since a plurality of sensors 30 can be connected to the relay machine 20, in such a case, a plurality of sensors 30 are assigned to a specific slot of the relay machine 20. For example, in the example of FIG. 5, the repeater 20e is assigned to the time slot in the column L3 and the row N1. Since the two sensors 30 are connected to the relay machine 20e (see FIG. 1), the two sensors 30 are substantially allocated to the time slot of the column L3 and the row N1.

  In the communication schedule, time slot processing proceeds in the column direction. For example, in a certain column (for example, L1), the processing of time slots proceeds in ascending order with respect to row numbers (that is, the order of rows N1 to Nm), and the time slot of the last row number (row Nm) of the row When the process is completed, the process proceeds in the same order from the time slot of the first row number (row N1) of the next column (for example, L2).

  The time slot is assigned by the data station 10 when a communication path is established. For example, a path is formed between communication terminals prior to establishment of the entire communication path of the wireless communication system 100. Thereafter, the data station 10 acquires route information indicating which communication terminals are connected to each other, and establishes the entire communication route of the wireless communication system 100. When the communication path is established, the data station 10 assigns a time slot to each repeater 20, and notifies each repeater 20 of the number of the specific slot. At this time, the relay 20 that needs to perform the relay process of the lower relay 20 is notified of the specific slot of the lower relay 20, that is, the relay slot, in addition to its own specific slot. Further, the relay device 20 notifies the connected sensor 30 of the specific slot of the relay device 20. The data station 10 stores the communication schedule (that is, allocation of the time slot to the repeater 20) in the storage unit 13. The repeater 20 stores the specific slot and the relay slot in the storage unit 23. The sensor 30 stores the specific slot of the connected repeater 20 in the storage unit 53.

In addition, the communication schedule includes an emergency time slot (hereinafter also referred to as “emergency slot”). The emergency time slot is a time slot assigned to all the repeaters 20 in common. In other words, no specific repeater 20 is assigned to the emergency time slot. The emergency time slot is a time slot for transmitting the detection data of the sensor 30 to the data station 10 at a timing other than the normal time slot to which the repeater 20 is assigned, and all the repeaters 20 are in an active state. It is a time slot. That is, in an emergency time slot, communication is possible via an arbitrary communication path. In the emergency slot in the present embodiment, when an abnormal detection value is detected by the sensor 30, the detection value is transmitted to the data station 10 without waiting for a specific slot of the repeater 20 to which the sensor 30 is connected. Used to do.
As described above, since the number of time slots included in the communication schedule is larger than the number of repeaters 20, the communication schedule includes time slots to which no repeaters 20 are assigned. As described above, one or a plurality of time slots among the time slots to which no repeater 20 is assigned are assigned as emergency time slots. The emergency time slot is also assigned by the data station 10 when the communication path is established as described above. In the communication schedule of FIG. 5, the time slots in the column L1 and row N3 and the time slots in the column L4 and row N3 are emergency time slots. The repeater 20 also stores the emergency slot in the storage unit 23. The sensor 30 is stored in the emergency slot storage unit 53.

<System operation>
In data collection, the data station 10 proceeds with processing according to a communication schedule. Specifically, the data station 10 performs processing necessary for the data station 10 in the time slot allocated to itself. Subsequently, the data station 10 sequentially communicates with the repeaters 20 assigned to the time slots in the order of the time slots. At this time, the signal sent from the data station 10 to each repeater 20 includes at least a request signal for requesting return of detection data from the sensor 30.

  On the other hand, the repeater 20 becomes active at the timing of a specific slot according to the communication schedule, and waits for a request signal from the data station 10. Further, the relay machine 20 acquires detection data from the sensor 30 connected to the relay machine 20 according to the specific slot. Therefore, the sensor 30 becomes active according to a specific slot of the connected relay device 20 and transmits the detection data to the relay device 20. When receiving the request signal, the relay device 20 returns detection data from the sensor 30 to the data station 10 as a response to the request signal. In addition, the relay machine 20 is also active in the relay slot, and performs relay processing between the data station 10 and the lower relay machine 20.

  In the basic process of data collection, the above process is repeated, and the detection data of the sensor 30 is collected in the data station 10.

  However, the sensor 30 determines whether or not the detection value needs to be transmitted to the data station 10 in addition to the basic processing described above, and transmits the detection value to the data station 10 if necessary. . Specifically, the sensor 30 monitors the detected value abnormality, and transmits the detected value to the data station 10 when the detected value abnormality is detected. More specifically, the sensor 30 is in an active state in accordance with a specific slot of the connected repeater 20 and transmits a detection value to the repeater 20, and other than the specific slot of the connected repeater 20 However, there is a second mode in which the detected value is monitored in the active state, and when an abnormal detected value is detected, the detected value is transmitted to the data station 10 in the emergency slot. The sensor 30 switches between the first mode and the second mode based on the detection value. The sensor 30 enters the first mode when the detected value is within the predetermined second range, and enters the second mode when the detected value is outside the second range. For example, the second range is a range in which it is necessary to monitor whether the detected value becomes an abnormal value although the detected value is a normal range. In the second mode, the sensor 30 monitors whether or not the detected value is within the first range. If the detected value is outside the first range, the detected value is sent to the data station 10 in the nearest emergency slot. Send. The first range is a range of normal detection values, and is a range wider than the second range. In the emergency slot, since all the repeaters 20 are in the active state, the detection value from any sensor 30 can be transmitted to the data station 10 via the repeater 20.

<Function block>
FIG. 6 is a functional block diagram of the repeater 20. The repeater 20 includes a sleep unit 201 and a communication unit 202 as functional blocks.

  The sleep unit 201 switches between the active state and the sleep state of the relay device 20 (specifically, the CPU 21). The sleep unit 201 includes a CPU 21 and a timer circuit 25. The CPU 21 serving as the sleep unit 201 enters the sleep state by setting the time at which the next active state is set in the timing circuit 25, and enters the active state by receiving a notification of arrival of the set time from the timing circuit 25.

  The communication unit 202 performs communication with other wireless communication in accordance with the processing of the repeater 20. The communication unit 202 includes the CPU 21 and the wireless communication circuit 24. For example, the communication unit 202 executes a reply process and a relay process.

  FIG. 7 is a functional block diagram of the sensor 30. The sensor 30 includes a sleep unit 301, a detection unit 302, a determination unit 303, and a communication unit 304 as functional blocks.

  The sleep unit 301 switches between an active state and a sleep state of the sensor 30 (specifically, the CPU 51). The sleep unit 301 includes a CPU 51 and a timer circuit 55. The CPU 51 as the sleep unit 301 sets the time when the next active state is set in the time counting circuit 55 and enters the sleep state, while receiving the notification of arrival of the set time from the time counting circuit 55, becomes the active state.

  The detection unit 302 detects a predetermined physical quantity. The detection unit 302 includes the sensor unit 40. The detection unit 302 detects the frequency and temperature of the steam trap T.

  The determination unit 303 determines whether the detection value of the detection unit 302 is within the second range. That is, the determination unit 303 performs mode determination for the first mode and the second mode. Further, the determination unit 303 determines whether or not the detection value of the detection unit 302 is within the first range, that is, whether or not the detection value should be transmitted to the data station 10.

  The communication unit 304 performs communication with other wireless communication. The communication unit 304 includes a CPU 51 and a wireless communication circuit 54. The communication unit 304 appropriately performs communication with other wireless communication according to the processing of the sensor 30. For example, the communication unit 304 transmits the detection data to the relay device 20 in the first mode, and transmits the detection data to the data station 10 via the relay device 20 in the second mode.

<Processing flow>
Hereinafter, processing of the relay machine 20 and the sensor 30 in data collection will be described in detail.

  First, the processing of the repeater 20 will be described with reference to the flowchart of FIG. As described above, the repeater 20 is in the active state in the specific slot, the relay slot, and the emergency slot, and is in the sleep state in the other time slots.

  The relay device 20 (sleep unit 201) in the active state sets the start time of the next time slot that should be in the active state in the timer circuit 25 (step Sa1). Specifically, the repeater 20 sets the start time of the time slot that comes next among the specific slot, the relay slot, and the emergency slot in the timer circuit 25. Thereafter, the relay device 20 goes from the active state to the sleep state (step Sa2).

  The timer circuit 25 continues to count the time and notifies the CPU 21 of the arrival of the time when the set time is reached. The CPU 21 receives the notification from the time measuring circuit 25 and changes from the sleep state to the active state (step Sa3).

  In step Sa4, the repeater 20 determines whether the current time slot is an emergency slot. If the slot is not an emergency slot, that is, if it is a specific slot or a relay slot, the repeater 20 proceeds to step Sa5, whereas if it is an emergency slot, the repeater 20 proceeds to step Sa8.

  In step Sa5, the repeater 20 determines whether the process to be performed is a reply process. That is, if the current time slot is a specific slot, the process to be performed is a reply process, and if the current time slot is a relay slot, the process to be performed is a relay process.

  If the process to be performed is a reply process, the repeater 20 waits for a request signal from the data station 10 (step Sa6). And the relay machine 20 (communication part 201) will transmit the detection data from the sensor 30 toward the data station 10, if a request signal is received (step Sa7). At this time, the relay device 20 transmits a detection signal for requesting a return of detection data to the sensor 30 and acquires the detection data from the sensor 30. The detection data may be acquired after receiving a request signal from the data station 10 or prior to receiving the request signal. When the transmission of the detection data is completed, the relay machine 20 returns.

  When the repeater 20 cannot receive the request signal during the specific slot, the repeater 20 gives up communication with the data station 10 in the current specific slot and returns without performing any special processing.

  On the other hand, if it is determined in step Sa5 that the process to be performed is a relay process, the relay machine 20 performs the relay process in step Sa8. In the relay process, regardless of the content of the received signal, the relay 20 transmits the signal to the next communication terminal on the communication path to the final transmission destination of the signal. For example, when receiving a request signal from the data station 10 to the lower relay 20 from the data station 10, the relay 20 (communication unit 201) sends the request signal to the next relay 20 on the communication path to the lower relay 20. Send. When the relay device 20 receives the detection data from the lower relay device 20 to the data station 10, the relay device 20 transmits the detection data to the next relay device 20 on the communication path to the data station 10. The relay machine 20 returns when the relay process is completed or when the time slot ends.

  Also, if the current time slot is an emergency slot, that is, if YES in step Sa4, the repeater 20 performs the relay process in step Sa8. In this case, when receiving the detection data from the sensor 30 to the data station 10, the relay device 20 transmits the detection data to the next relay device 20 on the communication path to the data station 10.

  By repeating the above flow, the repeater 20 becomes active in the specific slot, the relay slot, and the emergency slot, and performs processing according to the time slot at that time. The repeater 20 enters a sleep state except for the specific slot, the relay slot, and the emergency slot.

-Sensor-
Next, the process of the sensor 30 will be described. FIG. 9 is a flowchart showing processing of the sensor 30 in the first mode, and FIG. 10 is a flowchart showing processing of the sensor 30 in the second mode.

  First, the process of the sensor 30 in the first mode will be described with reference to FIG. As described above, the sensor 30 in the first mode is in an active state according to a specific slot of the connected repeater 20, and is in a sleep state at other times.

  The sensor 30 (sleep unit 301) in the active state in the first mode sets the start time of the next time slot that should be in the active state in the timer circuit 55 (step Sb1). Specifically, the sensor 30 sets the start time of the specific slot of the connected repeater 20 that arrives next in the timer circuit 55. Thereafter, the sensor 30 changes from the active state to the sleep state (step Sb2).

  The timer circuit 55 continues to count the time and notifies the CPU 51 of the arrival of the time when the set time is reached. In response to the notification from the time measuring circuit 55, the CPU 51 changes from the sleep state to the active state (step Sb3).

  In step Sb4, the sensor 30 waits for a detection signal from the repeater 20. When the sensor 30 receives the detection signal, the sensor unit 40 (detection unit 302) detects the frequency and temperature of the steam trap T (step Sb5), and the processing unit 50 (communication unit 304) detects the detection value (detection data). ) Is transmitted to the repeater 20 (step Sb6).

  Further, the sensor 30 (determination unit 303) determines whether or not the detected value is within the second range (step Sb7). Specifically, the sensor 30 determines whether or not the temperature is within the range of the second lower limit temperature Ta2 or more and the second upper limit temperature Tb2 or less, and the frequency is the second lower limit frequency Fa2 or more and the second upper limit temperature. It is determined whether or not the frequency is within the range of the frequency Fb2.

  If both the temperature and the frequency are within the second range, the sensor 30 returns and returns to step Sb1. Thereafter, the sensor 30 repeats the above-described processing.

  On the other hand, when at least one of the temperature and the frequency is out of the second range, the sensor 30 (communication unit 304) shifts from the first mode to the second mode in step Sb8.

  As described above, the sensor 30 in the first mode becomes active according to the specific slot of the connected repeater 20, transmits the detection value to the repeater 20, and enters the sleep state otherwise. That is, the sensor 30 transmits the detection value only in a specific slot of the connected relay machine 20 in one cycle of the communication schedule. At this time, the sensor 30 monitors the detection value in the specific slot, and shifts from the first mode to the second mode when the detection value is out of the second range.

  Next, the process of the sensor 30 in the second mode will be described with reference to FIG. The sensor 30 in the second mode is in an active state according to a specific slot of the connected repeater 20, and is in an active state every predetermined monitoring period. The monitoring cycle is a cycle shorter than one cycle of the communication schedule, for example, a cycle that arrives many times during one cycle of the communication schedule. In other cases, the sensor 30 enters a sleep state.

  The sensor 30 (sleep unit 301) in the active state in the second mode sets the time for the next active state in the time counting circuit 55 (step Sc1). Specifically, the sensor 30 in the second mode sets, in the clock circuit 55, the start time of the specific slot of the connected relay 20 and the earlier one of the monitoring periods. Thereafter, the sensor 30 changes from the active state to the sleep state (step Sc2).

  The timer circuit 55 continues to count the time and notifies the CPU 51 of the arrival of the time when the set time is reached. The CPU 51 changes from the sleep state to the active state in response to the notification from the timing circuit 55 (step Sc3).

  Subsequently, the sensor 30 determines whether or not the current slot is a specific slot (step Sc4). If the current slot is a specific slot, the sensor 30 proceeds to step Sc5. On the other hand, if the current slot is not a specific slot, that is, if the sensor 30 is in an active state due to the arrival of the monitoring cycle, the sensor 30 proceeds to step Sc10.

  If the current slot is a specific slot (YES in step Sc4), the sensor 30 performs the same process as in the first mode. That is, the processing of Step Sc5 to Step Sc8 is the same as the processing of Step Sb4 to Step Sb7 in the first mode. The sensor 30 waits for a detection signal from the connected repeater 20, receives the detection signal, acquires a detection value, and transmits the detection value (detection data) to the repeater 20. Thereafter, the sensor 30 determines whether to continue the second mode or shift to the first mode based on the detected value in step Sc8. Specifically, when the detected value is within the second range, the sensor 30 proceeds to step Sc9 and shifts from the second mode to the first mode, while the detected value is outside the second range. In the case, the sensor 30 returns and repeats the process from Step Sc1.

  On the other hand, when the sensor 30 is in the active state in the monitoring cycle, the sensor 30 (detection unit 302) acquires the detection value in step Sc10. And the sensor 30 (bottom part 303) determines whether a detected value is in a 1st range (step Sc11). Specifically, the sensor 30 determines whether or not the temperature is in the range of the first lower limit temperature Ta1 or more and the first upper limit temperature Tb1 or less, and the frequency is the first lower limit frequency Fa1 or more and the first upper limit temperature. It is determined whether or not it is within the range of the frequency Fb1 or less. The first lower limit temperature Ta1 is a temperature lower than the second lower limit temperature Ta2, and the first upper limit temperature Tb1 is a temperature higher than the second upper limit temperature Tb2. That is, the first range related to temperature is a wider range than the second range. The first lower limit frequency Fa1 is lower than the second lower limit frequency Fa2, and the first upper limit frequency Fb1 is higher than the second upper limit frequency Fb2. That is, the first range related to the frequency is a range wider than the second range.

  When both the temperature and the frequency are within the first range, the sensor 30 proceeds to step Sc8 and performs the above-described mode determination. On the other hand, if at least one of the temperature and the frequency is outside the first range, the sensor 30 proceeds to step Sc12.

  In step Sc <b> 12, the sensor 30 (sleep unit 301) sets, in the time counting circuit 55, the start time of the emergency slot and the specific slot that comes first. Thereafter, the sensor 30 changes from the active state to the sleep state (step Sc13). The timer circuit 55 continues to count the time and notifies the CPU 51 of the arrival of the time when the set time is reached. In response to the notification from the time measuring circuit 55, the CPU 51 changes from the sleep state to the active state (step Sc14). That is, the sensor 30 is activated in the emergency slot or the specific slot. Then, the sensor 30 transmits the detection value to the data station 10. In the emergency slot, as described above, since all the repeaters 20 are in the active state, the detection value is transmitted to the data station 10 via one or a plurality of repeaters 20. In addition, in the specific slot, the repeater 20 to which the sensor 30 is connected and the repeater 20 on the communication path between the data stations 10 are in an active state, so the detected value is one or more repeaters. 20 to the data station 10.

  As described above, the sensor 30 in the second mode performs the same process as in the first mode in accordance with the specific slot of the connected repeater 20, acquires the detection value for each monitoring period, and the detection value is the first value. Monitor whether it is within one range. When the detected value is out of the first range, the sensor 30 transmits the detected value to the data station 10 in the nearest emergency slot without waiting for the next specific slot. If the next specific slot comes before the emergency slot, the sensor 30 transmits the detection value to the data station 10 in the specific slot. Otherwise, the sensor 30 is in a sleep state. That is, the sensor 30 is in an active state not only in a specific slot of the connected repeater 20 but also in a monitoring cycle in one cycle of the communication schedule. However, the sensor 30 always transmits the detection value in the specific slot, but only acquires and determines the detection value in the monitoring period. The sensor 30 also determines whether or not the detected value is within the second range, that is, mode determination.

  The sensor 30 repeats the above flow to perform processing according to the mode while switching between the first mode and the second mode. Thereby, the sensor 30 can detect abnormal detection data at an early stage and transmit it to the data station 10 at an early stage while transmitting the detection data according to the time slot of the communication schedule.

<Frame configuration>
Here, a data frame configuration in the wireless communication system 100 will be described. FIG. 11 is a diagram illustrating a data frame configuration.

  The frame transmitted by the communication terminal includes an ID field 71 for storing the PAN ID, a DA field 72 for storing the address of one hop ahead, an SA field 73 for storing the address of the transmission source, and a final transmission destination A TA field 74 that stores an address, a CMD field 75 that stores a command, an FG field 76 that stores an emergency flag, and a data field 77 that stores detection data are included. The emergency flag is a flag that is turned on (set) when the sensor 30 in the second mode transmits a detection value to the data station 10 in the emergency slot, and is turned off at other times.

  For example, in a frame when transmitting detection data from the sensor 30 in the first mode to the repeater 20b, the DA field 72 stores the address of the repeater 20b one hop ahead. In the SA field 73, the address of the sensor 30 is stored. The TA field 74 stores the address of the repeater 20b that is the final transmission destination. The CMD field 75 stores a value corresponding to detection data transmission. The FG field 76 stores a value indicating that the emergency flag is off. In the data field 77, detection data of the sensor 30 is stored. Since the final transmission destination of the frame transmitted from the sensor 30 to the relay device 20 in the first mode is the relay device 20, the same address is stored in the DA field 72 and the TA field 74.

  In the frame when the relay 20b that has received the detection data from the sensor 30 in the first mode transmits the detection data to the data station 10, the DA field 72 contains the relay 20a that is one hop ahead. Stores the address. The SA field 73 stores the address of the repeater 20b. The TA field 74 stores the address of the data station 10 that is the final transmission destination. The CMD field 75 stores a value corresponding to detection data transmission. The FG field 76 stores a value indicating that the emergency flag is off. In the data field 77, detection data from the sensor 30 is stored.

  On the other hand, in the frame when transmitting detection data from the sensor 30 in the second mode to the repeater 20b, the DA field 72 stores the address of the repeater 20b that is one hop ahead. In the SA field 73, the address of the sensor 30 is stored. The TA field 74 stores the address of the data station 10 that is the final transmission destination. The CMD field 75 stores a value corresponding to detection data transmission. The FG field 76 stores a value indicating that the emergency flag is turned on. In the data field 77, detection data of the sensor 30 is stored.

  Then, in the frame when the relay device 20b receiving the detection data from the sensor 30 in the second mode relays the detection data, the DA field 72 stores the address of the relay device 20a one hop ahead. In the SA field 73, the address of the sensor 30 is stored. The TA field 74 stores the address of the data station 10 that is the final transmission destination. The CMD field 75 stores a value corresponding to detection data transmission. The FG field 76 stores a value indicating that the emergency flag is turned on. In the data field 77, detection data from the sensor 30 is stored.

  Thus, when the sensor 30 in the first mode transmits detection data, the address of the sensor 30 is stored in the SA field 73 of the frame transmitted from the sensor 30, and the connected relay is stored in the TA field 74. The address of the relay station 20 is stored, while the address of the relay station 20 is stored in the SA field 73 of the frame transmitted by the relay station 20 that has received the frame, and the address of the data station 10 is stored in the TA field 74. Stored.

  On the other hand, when the sensor 30 in the second mode transmits detection data, the address of the sensor 30 is stored in the SA field 73 of the frame transmitted from the sensor 30, and the address of the data station 10 is stored in the TA field 74. Stored. Since the relay device 20 that has received the frame only performs a relay process, the address of the sensor 30 is stored in the SA field 73 of the frame transmitted from the relay device 20, and the address of the data station 10 is stored in the TA field 74. Is stored. In addition, the emergency flag is turned on in the frame including the detection data of the sensor 30 in the second mode.

  Therefore, when the data station 10 receives the frame including the detection data, the data station 10 determines whether the detection data is from the first mode sensor 30 or the second mode sensor 30 based on the contents of the SA field 73 and the FG field 76. It is possible to determine whether the detected data is normal or abnormal.

  In the wireless communication system 100 configured as described above, the data station 10 communicates with the relay device 20 corresponding to each time slot, and collects detection data of the sensor 30 connected to the relay device 20. At this time, if the sensor 30 is in the first mode, the sensor 30 becomes active according to the specific slot of the connected relay 20 and transmits a detection value (detection data) to the relay 20. At other times, the sensor 30 is in a sleep state. Further, the sensor 30 determines whether or not the detection value needs to be frequently monitored based on the detection value. If the detection value is outside the second range, it is necessary to monitor, and the sensor 30 enters the second mode. Transition.

  In the second mode, the sensor 30 periodically enters an active state other than the specific slot of the connected repeater 20, acquires the detection value, and monitors whether the detection value is within the first range. . If the detected value is out of the first range, the sensor 30 becomes active in the emergency slot and transmits the detected value to the data station 10. In the emergency slot, all the repeaters 20 are in the active state and can communicate, so the detection data from the sensor 30 reaches the data station 10.

  Thus, when the sensor 30 detects abnormal detection data, the detection data can be delivered to the data station 10 in the emergency slot without waiting for the specific slot of the connected relay 20. As a result, the data station 10 can acquire abnormal detection data at an early stage.

  As described above, the wireless communication system 100 forms a network with a plurality of communication terminals. The plurality of communication terminals include a data station 10 (master unit) and a plurality of relay units 20 (slave units). The data station 10 communicates with a plurality of relays 20 according to a communication schedule divided into a plurality of time slots, and each of the plurality of relays 20 has a specific slot (a specific time slot among a plurality of time slots). ) And the communication schedule includes an emergency slot (emergency time slot) commonly assigned to the plurality of relay devices 20 in addition to the specific slot, and each of the plurality of relay devices 20 includes a specific slot. While communicating with the data station 10, communication with the data station 10 is possible in the emergency slot.

  That is, the repeater 20 is assigned a specific slot in the communication schedule divided into a plurality of time slots, and communicates with the data station 10 in the specific slot, while the data station in the emergency slot of the plurality of time slots. 10 is communicable.

  According to this configuration, each repeater 20 basically communicates with the data station 10 in a specific slot. However, if it is necessary to communicate with the data station 10 at other times, the relay 20 Communication with the data station 10 can be performed in the slot. Thereby, the repeater 20 can communicate with the data station 10 at an early stage without waiting for a specific slot.

  The plurality of communication terminals detect the frequency and temperature (predetermined physical quantity) of the steam trap T, and transmit the detected values to the connected (corresponding) relay devices 20 among the plurality of relay devices 20. Each of the plurality of sensors 30 transmits the detection value to the relay device 20 connected in a specific slot of the connected relay device 20, while the detection value is transmitted to the data station at a timing other than the specific slot. When it is necessary to transmit to 10, the detected value is transmitted to the repeater 20 connected in the emergency slot.

  That is, the sensor 30 includes a sensor unit 40 that detects a predetermined physical quantity, and a processing unit 50 that transmits a detection value of the sensor unit 40 to another communication terminal. The processing unit 50 is divided into a plurality of time slots. When it is necessary to transmit a detection value at a timing other than the specific slot to the repeater 20 to which the specific slot is assigned in the communication schedule, it is necessary to transmit the detection value at a timing other than the specific slot. The detected value is transmitted to the repeater 20 in the emergency slot.

  According to this configuration, the sensor 30 communicates with the relay device 20, and the detection value (detection data) of the sensor 30 is transmitted to the data station 10 via the relay device 20. As described above, since the relay machine 20 communicates with the data station 10 in a specific slot, the sensor 30 also transmits a detection value to the relay machine 20 in the specific slot of the connected relay machine 20. As a result, the detection value is transmitted from the repeater 20 to the data station 10. However, when the detection value needs to be transmitted to the data station 10, the sensor 30 transmits the detection value to the relay device 20 in the emergency slot. Since all the repeaters 20 are communicable with the data station 10 in the emergency slot, whichever sensor 30 outputs the detected value, the detected value is transmitted via the repeater 20 to the data station 10. To reach.

  Each of the plurality of sensors 30 determines whether or not a detection value needs to be transmitted to the data station 10, and when it is determined that the detection value needs to be transmitted to the data station 10, The detected value is transmitted to the connected relay device 20.

  According to this configuration, the necessity for transmitting the detection value to the data station 10 is determined by the sensor 30. That is, the sensor 30 itself determines the necessity of transmission of the detection value, and if necessary, transmits the detection value to the repeater 20 connected in the emergency slot.

  Further, each of the plurality of sensors 30 determines that the detected value needs to be transmitted to the data station 10 when the detected value is outside the predetermined first range.

  According to this configuration, the necessity for transmission of the detection value is determined based on the detection value. Specifically, when the detected value is out of the first range, it is determined that the detected value needs to be transmitted. For example, the first range is set to a normal detection value range. In this case, when an abnormal detection value is detected, the detection value is transmitted from the sensor 30 to the data station 10 in the emergency slot.

  Each of the plurality of sensors 30 detects the frequency and temperature of the steam trap T at a timing corresponding to a specific slot of the connected repeater 20, and transmits the detected value to the connected repeater 20. The frequency and temperature are detected at a timing that does not correspond to the mode and the specific slot of the connected repeater 20, and it is determined whether or not the detected value is within the first range. And a second mode in which the detected value is transmitted to the repeater 20 connected to the slot.

  According to this configuration, when the sensor 30 in the first mode acquires the detection value, the detection value is transmitted to the relay device 20. Therefore, even if a detection value outside the first range is acquired in the first mode, the detection value is immediately transmitted to the data station 10 via the repeater 20.

  On the other hand, in the second mode, the detection value is acquired even at a timing that does not correspond to the specific slot. Basically, if the slot is not a specific slot, the repeater 20 does not communicate with the data station 10, so even if the sensor 30 acquires a detection value outside the first range at a timing not corresponding to the specific slot, the detection is performed. The value cannot be sent immediately to the data station 10. On the other hand, when the sensor 30 in the second mode acquires a detection value outside the first range at a timing not corresponding to the specific slot, the detection value is transmitted to the relay device 20 in the emergency slot. In the emergency slot, all the repeaters 20 are communicable with the data station 10, so that the detection value reaches the data station 10. If the specific slot arrives earlier than the emergency slot when the detection value outside the first range is acquired, the sensor 30 transmits the detection value to the relay device 20 in the specific slot. In the specific slot, the repeater 20 to which the specific slot is assigned communicates with the data station 10, so that the detection value reaches the data station 10.

<< Embodiment 2 >>
Next, the process of the sensor 30 in the second mode according to the second embodiment will be described. The configuration of the wireless communication system 100 is the same as that of the first embodiment. FIG. 12 is a flowchart illustrating processing of the sensor 30 in the second mode according to the second embodiment.

  In the second embodiment, the processing of the repeater 20 and the processing of the first mode sensor 30 are the same as those of the first embodiment, and the processing of the second mode sensor 30 is different from the first embodiment. The sensor 30 in the second mode is the same as in the first embodiment in that it is in the active state in the monitoring period and the specific slot, but the processing after acquiring the detection value in the monitoring period is different.

  Specifically, after acquiring the detected value in the monitoring period (step Sc10), the sensor 30 determines whether the first one of the monitoring period, the specific slot, and the emergency slot is the emergency slot (step Sc16). ).

  If the first arrival is not an emergency slot, the sensor 30 proceeds to step Sc8. Step Sc8 is a step for performing mode determination as in the first embodiment. That is, the sensor 30 determines whether or not the detected value is within the second range. If the detected value is within the second range, the sensor 30 proceeds to the first mode, and if the detected value is outside the second range, Continue 2 mode.

  On the other hand, if the first incoming slot is an emergency slot, the sensor 30 determines in step Sc11 whether the detected value is within the first range. Step Sc11 is the same as in the first embodiment, and is a step for determining whether or not the detected value is within a normal range. If the detected value is within the first range, the sensor 30 proceeds to step Sc8.

  On the other hand, if the detected value is outside the first range, the sensor 30 sets the start time of the emergency slot in the timer circuit 55 in step Sc17. Thereafter, the sensor 30 performs the processes of Steps Sc13 to Sc15 as in the first embodiment. That is, the CPU 51 changes from the active state to the sleep state (step Sc13), and the CPU 51 changes from the sleep state to the active state according to the notification from the timer circuit 55 (step Sc14). Then, the sensor 30 transmits the detection value to the data station 10.

  As described above, the second mode sensor 30 determines whether or not the detection value is within the first range only when the detection value is acquired in the monitoring period immediately before the emergency slot, and other than immediately before the emergency slot. In the monitoring cycle, after the detection value is acquired, only mode determination is performed.

  In short, the sensor 30 in the second mode acquires a detection value at least immediately before the emergency slot, and determines whether or not the detection value is within the first range. As a result, even if the specific slot does not arrive, the detection value is acquired. If the detection value is outside the first range, the detection value is transmitted to the repeater 20 and thus to the data station 10 in the emergency slot. . As a result, the sensor 30 can detect abnormal detection data at an early stage and transmit it to the data station 10 at an early stage.

<< Other Embodiments >>
As described above, the embodiment has been described as an example of the technique disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to an embodiment in which changes, replacements, additions, omissions, and the like are appropriately performed. Moreover, it is also possible to combine each component demonstrated by the said embodiment and it can also be set as a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the technology. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

  About the said embodiment, it is good also as following structures.

  For example, the wireless communication system 100 may be applied to other than the steam system. The sensor 30 detects the frequency and temperature of the steam trap T, but may detect other physical quantities (for example, electric power).

  Furthermore, although the relay machine 20 acquires the detection data of the sensor 30 and transmits it to the data station 10, data other than the detection data of the sensor 30 may be transmitted to the data station 10. That is, basically, the data station 10 exchanges data with the repeater 20 corresponding to each specific slot, and when necessary, the data station 10 and the repeater 20 in the emergency slot exchange necessary data. The structure which communicates may be sufficient.

  In the communication schedule, time slots may not be defined in a matrix. The time slot allocation to the relay device 20 may not be performed for each network hierarchy. Further, one specific slot is assigned to one repeater 20, but two or more specific slots may be assigned to one repeater 20.

  Furthermore, the number of emergency slots in the communication schedule is not limited to two. The number of emergency slots may be 1 or 3 or more.

  The sensor 30 determines that the detected value needs to be transmitted to the data station 10 (master unit) when the detected value is outside the predetermined first range, but is not limited to this. . It can be arbitrarily set what determines that the detection value needs to be transmitted to the parent device. Furthermore, the first range is not limited to the range of normal detection values, and can be set arbitrarily. Similarly, the second range for switching between the first mode and the second mode can also be set arbitrarily.

  Furthermore, although the first range and the second range are defined by both the upper limit value and the lower limit value, only one of them may be used. For example, the first range of temperature may be a range that is equal to or higher than the first lower limit temperature Ta1, and the second range of temperature may be a range that is equal to or higher than the second lower limit temperature Ta2 (> Ta1).

  The timing at which the sensor 30 in the second mode acquires the detection value may be any timing as long as it does not correspond to the specific slot. That is, the sensor 30 in the second mode may not periodically detect the detection value as in the monitoring cycle. For example, the sensor 30 in the second mode may acquire the detection value in the emergency slot without acquiring the detection value in the monitoring cycle. That is, the sensor 30 in the second mode detects and transmits the detection value in the specific slot similarly to the first mode, detects and determines the detection value in the emergency slot, and transmits the detection value if necessary. You may make it do.

  Moreover, in the said embodiment, although the sensor 30 determines whether it is necessary to transmit a detected value to a main | base station, the relay machine 20 with which the sensor 30 is connected may determine. That is, the sensor 30 only acquires the detection data and transmits it to the relay device 20. In that case, the repeater 20 needs to be in the active state at the same timing as the sensor 30 in the second mode is in the active state. That is, the repeater 20 has a first mode and a second mode as in the case of the sensor 30, and in the second mode, it is necessary to be in an active state every monitoring period.

  The above-described flowchart is merely an example, and the above-described steps may be executed by changing the order, may be executed in parallel, or may be omitted. For example, in the flowchart of FIG. 9, after acquiring the detection value, the sensor 30 transmits the detection data to the relay device 20 (step Sb6), and then determines whether the detection value is within the second range. However (step Sb7), detection data transmission and detection value determination may be performed in reverse order or in parallel.

  As described above, the technology disclosed herein is useful for wireless communication systems and communication terminals.

100 wireless communication system 10 data station (communication terminal, base unit)
20 Repeater (communication terminal, slave unit)
30 sensor (communication terminal)

Claims (5)

A wireless communication system that forms a network with a plurality of communication terminals,
The plurality of communication terminals include a master unit, a plurality of slave units, and a plurality of sensors that detect a predetermined physical quantity and transmit a detection value to a corresponding slave unit among the plurality of slave units. ,
The master unit communicates with the plurality of slave units according to a communication schedule divided into a plurality of time slots,
Each of the plurality of slave units is assigned a specific time slot among the plurality of time slots,
The communication schedule includes, in addition to the specific time slot, an emergency time slot assigned in common to the plurality of slave units,
Each of the plurality of slave units communicates with the master unit in the specific time slot, while being able to communicate with the master unit in the emergency time slot,
Each of the plurality of sensors is
While transmitting the detected value to the corresponding slave unit in the specific time slot of the corresponding slave unit,
When the detection value needs to be transmitted to the parent device at a timing other than the specific time slot, the detection value is transmitted to the corresponding child device in the emergency time slot. Wireless communication system. The wireless communication system according to claim 1, wherein
Each of the plurality of sensors determines whether or not the detection value needs to be transmitted to the parent device, and the emergency time is determined when it is determined that the detection value needs to be transmitted to the parent device. A wireless communication system, wherein the detected value is transmitted to the corresponding slave unit in a slot. The wireless communication system according to claim 2,
Each of the plurality of sensors determines that it is necessary to transmit the detected value to the parent device when the detected value is outside a predetermined first range. The wireless communication system according to claim 3,
Each of the plurality of sensors is
A first mode in which the physical quantity is detected at a timing corresponding to the specific time slot of the corresponding slave unit, and the detected value is transmitted to the corresponding slave unit;
When the physical quantity is detected at a timing that does not correspond to the specific time slot of the corresponding slave unit, it is determined whether or not the detection value is within the first range, and when the detection value is outside the first range And a second mode in which the detected value is transmitted to the corresponding slave unit in the emergency time slot. A network is formed by a plurality of communication terminals including a parent device, a plurality of child devices, and a plurality of sensors that detect a predetermined physical quantity and transmit a detection value to a corresponding child device among the plurality of child devices. A sensor in a wireless communication system in which the master unit communicates with the plurality of slave units according to a communication schedule divided into a plurality of time slots,
A sensor unit for detecting a predetermined physical quantity;
A processing unit that transmits the detection value of the sensor unit to the corresponding slave unit ,
The processor is
While transmitting the detection value to the corresponding slave unit in a specific time slot assigned to the corresponding slave unit among the plurality of time slots ,
When it becomes necessary to transmit the detection value at a timing other than the specific time slot, the detection value is transmitted to the corresponding slave unit in an emergency time slot of the plurality of time slots. A featured sensor .

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