JP2013235348A - Radio communication system, radio sensor, and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption of a radio sensor.SOLUTION: A sensor circuit 31 detects a given physical quantity concerning environment in a predetermined area. A memory 36 stores a detection history table indicating a detection history of the physical quantity. A CPU 38 acquires a detection result by the sensor circuit 31 at every first time interval, and determines necessity of transmitting data to a radio master station on the basis of the acquired detection result and the detection history table. When the CPU 38 determines that it is necessary to transmit data, the CPU 38 transmits detection data including the detection result to the radio master station via a radio communication I/F 32, and also, regardless of the determination result, stores the detection result and the current time in association in the detection history table.

Description

  The present invention relates to a technique for suppressing power consumption of a sensor in wireless communication between a battery-powered sensor and a host station.

  For example, in an air conditioning system that controls an air conditioner installed in a building or the like, a plurality of sensors are installed in an air conditioning target area, and a host controller (system controller) uses the temperature detected by the sensors to Perform air conditioning control of the air conditioning target area.

  Each sensor wirelessly transmits detection data storing detection results to the wireless master station. For example, the wireless master station is connected to the system controller by wire, and transmits detection data from each sensor to the system controller.

  A sensor that performs such wireless communication (wireless sensor) generally includes a battery and is driven by receiving power from the battery. For this reason, when the capacity of the battery is lost or decreased, the sensing function is hindered and the battery needs to be replaced. Therefore, in this type of wireless sensor, it can be said that extending the battery life is one of important issues.

  For example, in Patent Document 1, in a wireless system including a plurality of slave stations that report observation data, monitoring data, and the like at a specified time, each slave station is connected to a transmission / reception unit at a time other than a predetermined transmission / reception time. A technique is disclosed in which the power supply is stopped and the power is transmitted to the transmission / reception means spontaneously at a transmission / reception start time specified in advance to reduce the power consumption of each slave station and the like.

JP 2004-53355 A

  By the way, in a control target space (control target area) such as air conditioning, a predetermined physical quantity (for example, temperature) regarding the environment tends to be substantially the same as the detection result at the same time on the previous day. However, regarding the reduction of the power consumption of the wireless sensor, in reality, an effective technique focusing on the characteristic of the physical quantity detected by the wireless sensor has not been proposed yet.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a wireless communication system or the like that can further reduce the power consumption of a wireless sensor.

In order to achieve the above object, a wireless communication system according to the present invention includes:
A wireless communication system comprising a wireless sensor and a wireless master station,
The wireless sensor is
An environmental physical quantity detector that detects a predetermined physical quantity relating to the environment of a predetermined area;
A detection history storage unit that stores a detection history table indicating a detection history of the physical quantity;
A first communication unit that performs wireless communication with the wireless master station;
The detection result of the environmental physical quantity detection unit is acquired every time the first time elapses, and it is determined whether or not data transmission to the wireless master station is necessary based on the acquired detection result and the detection history table. When it is determined that it is necessary, the detection data including the detection result is transmitted to the wireless master station via the first communication unit, and the detection result and the current A first control unit that stores time in association with the detection history table,
The wireless master station is
A second communication unit that performs wireless communication with the wireless sensor;
A third communication unit that communicates with other devices via a predetermined network;
A reception history storage unit for storing a reception history table indicating a reception history of the detection data from the wireless sensor;
When the detection data is received via the second communication unit, the received detection data is transmitted to the other device via the third communication unit, and the received detection data and the current time are A second control unit that associates and stores in the reception history table,
The second control unit, when an elapsed time after storing the detection data in the reception history table exceeds a time obtained by adding a second time shorter than the first time to the first time The detection data satisfying a predetermined condition is read from the reception history table, data based on the read detection data is transmitted to the other device via the second communication unit, and the transmitted data and the current time The time before the second time is associated and stored in the reception history table.

  According to the present invention, the wireless sensor determines whether or not the detection data needs to be transmitted to the wireless master station based on the detection result of the predetermined physical quantity related to the environment of the area and the detection history. Therefore, it is possible to further reduce the power consumption required for the communication processing of the wireless sensor.

It is a figure which shows the whole structure of the equipment management system provided with the radio | wireless communications system which concerns on Embodiment 1 of this invention. 1 is a block diagram illustrating a configuration of a wireless sensor according to a first embodiment. 3 is a flowchart illustrating a procedure of detection data transmission processing according to the first embodiment. 1 is a block diagram illustrating a configuration of a wireless master station according to a first embodiment. 3 is a flowchart illustrating a procedure of wireless sensor handling processing according to the first embodiment. 6 is a graph for explaining an example of an effect of the wireless communication system according to the first embodiment. 6 is a graph for explaining an example of an effect by the wireless communication system of the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram illustrating an overall configuration of a facility management system including a wireless communication system 7 according to Embodiment 1 of the present invention. This facility management system is installed in an office building, for example, and includes a system controller 1, a wireless master station 2, wireless sensors 3A and 3B, and facility equipment 4, as shown in FIG. The system controller 1 and the wireless master station 2 are connected to the first network 5. The first network 5 is, for example, a network based on Modbus specifications. The system controller 1 is a programmable logic controller (PLC) generally called a sequencer, for example, and the equipment 4 is connected to the second network 6 and controlled by the system controller 1. Note that the wireless master station 2 and the equipment 4 may be connected on the same network.

  The equipment management system is a system for performing air conditioning, lighting, etc. according to the situation of a predetermined area in the office building. The system controller 1 controls the operation of the equipment 4 (for example, an air conditioner, an illuminator, etc.) based on a predetermined physical quantity (temperature, humidity, illuminance, etc.) in the predetermined area detected by the wireless sensors 3A, 3B. I do. In the present embodiment, the equipment 4 is an air conditioner, and the wireless sensors 3A and 3B have sensor functions for detecting the temperature and humidity of the air-conditioning target area of the equipment 4 respectively. Although not shown, a plurality of wireless master stations 2 can be connected to the first network 5. A plurality of facility devices 4 can be connected to the second network 6.

  The wireless communication system 7 includes a wireless master station 2 and wireless sensors 3A and 3B. As shown in FIG. 2, the wireless sensors 3A and 3B include a sensor circuit 31, a wireless communication I / F 32, a clock circuit 33, a timer 34, an oscillation circuit 35, a memory 36, a battery 37, and a CPU 38. .

  The sensor circuit 31 (environmental physical quantity detection unit) is a circuit for detecting temperature in the wireless sensor 3A and detecting humidity in the wireless sensor 3B. The wireless communication I / F (interface) 32 (first communication unit) communicates with the wireless master station 2 by a predetermined wireless communication method. The clock circuit 33 is a circuit that generates time information. The timer 34 is an interval timer that generates an interrupt to the CPU 38 at a predetermined time interval (for example, one minute interval).

  The oscillation circuit 35 is configured by a crystal oscillator or the like, and supplies a clock having a predetermined frequency to the timer 34 and the CPU 38. The memory 36 includes a readable / writable non-volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, and the like. A predetermined program, data used when the program is executed, and will be described later. A detection history table or the like is stored.

  The battery 37 is a primary battery or a secondary battery that supplies power to each component of the wireless sensor 3A (3B). A CPU (Central Processing Unit) 38 (first control unit) performs overall control of the wireless sensor 3A (3B). Further, the CPU 38 executes detection data transmission processing described below in accordance with the above-described program stored in the memory 36.

  FIG. 3 is a flowchart showing a procedure of detection data transmission processing executed by the CPU 38. When interrupted by the timer 34, the CPU 38 executes the following detection data transmission process.

  First, the CPU 38 acquires a result (sensor data) detected by the sensor circuit 31 (step S101). The CPU 38 acquires the current time (date and time) from the clock circuit 33 (step S102). The CPU 38 reads out sensor data detected at the same time on the previous day from the detection history table stored in the memory 36 (step S103). Then, the CPU 38 determines whether or not the sensor data acquired from the sensor circuit 31 matches the read sensor data (step S104). Here, the detection history table is a data table in which the detection history of sensor data for a predetermined past period (for example, one day) is stored.

  As a result of the determination, if the two do not match (step S104; NO), the CPU 38 stores the acquired sensor data (that is, the current time) and the ID (identification information) of the wireless sensor 3A (3B). Data is transmitted to the wireless master station 2 via the wireless communication I / F 32 (step S105). Then, the CPU 38 associates the current sensor data with the current time and stores them in the detection history table (step S106).

  On the other hand, if the two match (step S104; YES), the CPU 38 performs the process of step S106 without transmitting the detection data to the wireless master station 2.

  Next, the wireless master station 2 will be described. As shown in FIG. 4, the wireless master station 2 includes a wireless communication I / F 21, a clock circuit 22, an oscillation circuit 23, a memory 24, a wired communication I / F 25, a power receiving circuit 26, and a CPU 27. Prepare.

  The wireless communication I / F 21 (second communication unit) communicates with the wireless sensors 3A and 3B by a predetermined wireless communication method. The clock circuit 22 is a circuit that generates time information. The oscillation circuit 23 is configured by a crystal oscillator or the like, and supplies a clock having a predetermined frequency to the CPU 27. The memory 24 includes a readable / writable non-volatile semiconductor memory such as a RAM, a ROM, and a flash memory, and stores a predetermined program, data used when the program is executed, a reception history table described later, and the like.

  The wired communication I / F 25 (third communication unit) is connected to the transmission line (communication cable) of the first network 5 and uses a predetermined communication method (for example, a communication method compliant with the Modbus specification) to control the system controller. 1 and data communication via the first network 5. In addition, the wired communication I / F 25 supplies power received from the power supply line included in the communication cable to the power receiving circuit 26.

  The power receiving circuit 26 includes a current smoothing circuit, a voltage conversion regulator, and the like, and converts power supplied from the wired communication I / F 25 into power of a specific voltage so that each component of the wireless master station 2 can use the power. Then, the converted power is supplied to each component.

  The CPU 27 (second control unit) performs overall control of the wireless master station 2. In addition, the CPU 27 executes a wireless sensor handling process described below according to the program stored in the memory 24.

  FIG. 5 is a flowchart showing a procedure of wireless sensor correspondence processing executed by the CPU 27. When the detection data from the wireless sensor 3A or 3B is received by the wireless communication I / F 21 (step S201; YES), the CPU 27 transmits the received detection data to the system controller 1 via the wired communication I / F 25. (Step S202). The CPU 27 acquires the current time (date and time) from the clock circuit 22 (step S203), associates the received detection data with the acquired current time, and corresponds to the transmission source wireless sensor (3A or 3B). Store in the reception history table (step S204). Moreover, after resetting the non-reception time for the wireless sensor (3A or 3B) to 0, the CPU 27 starts counting the non-reception time again.

  Here, the reception history table is a data table storing reception histories of detection data for a predetermined period in the past (for example, one day). In the present embodiment, two reception history tables for the wireless sensors 3 </ b> A and 3 </ b> B are stored in the memory 24.

  When none of the detection data of the wireless sensors 3A and 3B has been received (step S201; NO), or after the processing of step S204, the CPU 27 does not receive any of the detection data of the wireless sensors 3A or 3B ( It is determined whether or not (unreceived time) exceeds the first time + the second time (step S205). Here, the first time is equal to a time interval (for example, one minute interval) at which the timer 34 interrupts the CPU 38 in the wireless sensor 3A (3B). The second time is shorter than the first time. For example, when the first time is 1 minute, the second time is set to about 10 seconds or less.

  As a result of the determination, if any of the non-reception times corresponding to the wireless sensors 3A and 3B does not exceed the first time + the second time (step S205; NO), the processing of the CPU 27 proceeds to step S201. Return. On the other hand, if any of the unreceived times exceeds the first time + the second time (step S205; YES), the CPU 27 acquires the current time from the clock circuit 22 (step S206), and the corresponding reception. The detection data at the same time on the previous day is read from the history table (step S207). The same time here means a time before the second time from the acquired current time.

  The CPU 27 transmits the read detection data to the system controller 1 via the wired communication I / F 25 (step S208). Further, the CPU 27 associates the read detection data with the time before the second time from the acquired current time, and stores it in the corresponding reception history table (step S209). Moreover, after resetting the non-reception time for the wireless sensor (3A or 3B) to 0, the CPU 27 starts counting the non-reception time again. Then, the process of the CPU 27 returns to step S201.

  As described above, according to the wireless communication system 7 of the present embodiment, the wireless sensor 3A (3B) can detect the wireless master station 2 when the detected sensor data matches the sensor data detected at the same time on the previous day. Does not send detection data to For example, in FIG. 6, the corresponding detection data is not transmitted for the sensor data detected at the time indicated by the circle. When the detection data from the wireless sensor 3 </ b> A (3 </ b> B) is not sent at a predetermined time interval, the wireless master station 2 transmits the detection data at the same time on the previous day to the system controller 1. Therefore, the power consumption of the wireless sensor 3A (3B) can be further reduced as compared with the conventional case.

  In the present embodiment, the wireless sensor 3A (3B) compares the detected sensor data with the sensor data detected at the same time on the previous day, but any past sensor stored in the detection history table. Choosing data for comparison is an arbitrary design matter. For example, the detection history of sensor data for the past year may be stored in the detection history table, and sensor data detected at the same time one year ago may be selected as a comparison target. In this case, if the detection data from the wireless sensor 3A (3B) is not sent at a predetermined time interval, the wireless master station 2 receives it at the same time one year ago (more specifically, one year The detection data (stored in the reception history table at the same time before) may be transmitted to the system controller 1.

  Further, the wireless sensor 3A (3B) may compare the detection history with a predetermined statistical process and the detected sensor data. For example, the wireless sensor 3A (3B) compares the average of the sensor data detected at the same time in the past week with the detected sensor data, and if the detected sensor data matches the above average, the wireless sensor 3A (3B) The detection data may not be transmitted to the master station 2. In this case, if the detection data from the wireless sensor 3A (3B) is not sent at a predetermined time interval, the wireless master station 2 determines the past one week from the reception history table corresponding to the wireless sensor 3A (3B). Read detection data for minutes. Then, the wireless master station 2 calculates the average of the sensor data included in the detection data at the same time, and transmits the detection data storing the calculated average and the ID of the wireless sensor 3A (3B) to the system controller 1. do it.

  In addition, in the comparison between the detected sensor data and the sensor data at the same time on the previous day, the wireless sensor 3A (3B) is not limited to the wireless parent 3A when the difference between the two is within a predetermined range. The detection data may not be transmitted to the station 2. This range (difference range) may be fixed, or may be changed by the system controller 1 or the wireless master station 2 under a predetermined condition and notified to the wireless sensor 3A (3B). In this way, for example, the wireless sensor 3A (3B) does not need to transmit detection data corresponding to sensor data that has changed at a level that may be regarded as an error range in the control of the equipment 4 and is consumed. Further reduction in power can be expected.

  In the above-described modification, for example, the system controller 1 and the wireless master station 2 may change the difference range based on the remaining capacity of the battery 37 of the wireless sensor 3A (3B). In this case, the wireless sensor 3 </ b> A (3 </ b> B) may include the remaining capacity of the battery 37 (e.g., shown in five stages 1 to 5 in ascending order of capacity) in the detection data to be transmitted. In this way, for the wireless sensor 3A (3B) having a small remaining capacity, the battery 37 can be prevented from suddenly running out by increasing the difference range and suppressing the frequency of detection data transmission.

  Further, the system controller 1 and the wireless master station 2 may change the difference range according to a time zone, a day of the week, a holiday, and the like. For example, the difference range is increased when there are no or few people in the control area of the equipment 4 such as at night, overtime, weekends, and holidays. In this way, the power consumption of the wireless sensor 3A (3B) can be further reduced without impairing the user's comfort.

(Embodiment 2)
Subsequently, Embodiment 2 of the present invention will be described. In the following description, the same reference numerals are given to components common to the first embodiment, and the description thereof is omitted.

  In the wireless communication system of the second embodiment, the wireless sensor 3A (3B) compares the data obtained by adding or subtracting the adjustment value to the detected sensor data with the sensor data detected at the same time on the previous day, If they match, the detection data is not transmitted to the wireless master station 2.

  This adjustment value is determined by the wireless master station 2 and notified to the wireless sensor 3A (3B). More specifically, the CPU 27 of the wireless master station 2 and the sensor data included in the detection data sent from the wireless sensor 3A (3B) at a predetermined timing (for example, a specific time every day) and the same time of the previous day. The above adjustment value is calculated by comparing the detected sensor data and obtaining the difference. Then, the CPU 27 of the wireless master station 2 sends the adjustment request data storing the calculated adjustment value and the information (addition / subtraction instruction information) indicating either addition or subtraction via the wireless communication I / F 21 to the wireless sensor 3A. To (3B). In addition, the CPU 27 stores the calculated adjustment value and addition / subtraction instruction information in the memory 24.

  When the CPU 38 of the wireless sensor 3A (3B) receives the adjustment request data from the wireless master station 2 via the wireless communication I / F 32, the CPU 38 extracts the adjustment value and the addition / subtraction instruction information from the adjustment request data, 36. In the subsequent detection data transmission process, the CPU 38 adds or subtracts the adjustment value to the detected sensor data according to the addition / subtraction instruction information. Then, the CPU 38 compares the data obtained thereby with the sensor data detected at the same time on the previous day, and if they match, the detected data is not transmitted to the wireless master station 2.

  When the detection data from the wireless sensor 3A (3B) is not sent even if a predetermined time (first time + second time) elapses in the wireless sensor compatible processing, the CPU 27 of the wireless master station 2 1 The sensor data is extracted from the detection data received at the same time of the previous year (more specifically, stored in the reception history table), and the adjustment value is applied to the extracted sensor data according to the addition / subtraction instruction information. Add or subtract. The CPU 27 generates detection data storing the obtained data and transmits it to the system controller 1. Further, the CPU 27 associates the transmitted detection data with the time before the second time from the current time, and stores it in the corresponding reception history table.

  As described above, according to the wireless communication system of the present embodiment, the wireless sensor 3A (3B) is configured such that the data obtained by adding the adjustment value to the detected sensor data matches the sensor data at the same time on the previous day. Does not transmit detection data to the wireless master station 2. Therefore, for example, as shown in FIG. 7, although the trend of fluctuations in sensor data is similar to the previous day, there are no or few matching time points in the sensor detected today and the sensor data detected the previous day. Even if it exists, the transmission frequency of the detection data from the wireless sensor 3A (3B) can be suppressed, and the power consumption can be reduced.

  In the present embodiment, the adjustment value is determined by the wireless master station 2 and notified to the wireless sensor 3A (3B), but may be determined by the wireless sensor 3A (3B). In this case, the CPU 38 of the wireless sensor 3A (3B) compares the detected sensor data with the sensor data detected at the same time of the previous day at a predetermined timing (for example, a specific time every day) to obtain a difference. Thus, the adjustment value is calculated. The CPU 38 transmits adjustment request data storing the calculated adjustment value and addition / subtraction instruction information to the wireless master station 2 via the wireless communication I / F 32. Further, the CPU 38 stores the calculated adjustment value and addition / subtraction instruction information in the memory 36.

  When the CPU 27 of the wireless master station 2 receives the adjustment request data from the wireless sensor 3A (3B) via the wireless communication I / F 21, the CPU 27 extracts the adjustment value and the addition / subtraction instruction information from the adjustment request data, 24. The subsequent processing is as described above for both the wireless master station 2 and the wireless sensor 3A (3B).

  Further, the adjustment value may indicate a slope such as an increase rate or a decrease rate instead of a difference value from the sensor data detected at the same time on the previous day. In this case, for example, the CPU 38 of the wireless sensor 3A (3B), in the detection data transmission process, the data obtained by multiplying the detected sensor data by this adjustment value and the sensor data detected at the same time on the previous day. And compare. If the two match, detection data may not be transmitted to the wireless master station 2.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  For example, the wireless sensor 3A (3B) always detects every predetermined time (for example, 1 hour) even when the detected sensor data (or data obtained by adding or subtracting the adjustment value) matches the data at the same time on the previous day. The detection data may be transmitted to the wireless master station 2. In this way, it is possible to prevent a situation in which the wireless sensor 3A (3B) is overlooked despite the failure of the wireless sensor 3A (3B), the battery being exhausted, or the like.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. Further, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 System controller 2 Radio | wireless master station 3A, 3B Wireless sensor 4 Equipment 5 First network 6 Second network 7 Wireless communication system 21, 32 Wireless communication I / F
22, 33 Clock circuit 23, 35 Oscillation circuit 24, 36 Memory 25 Wired communication I / F
26 Power receiving circuit 27, 38 CPU
31 sensor circuit 34 timer 37 battery

Claims (5)

A wireless communication system comprising a wireless sensor and a wireless master station,
The wireless sensor is
An environmental physical quantity detector that detects a predetermined physical quantity relating to the environment of a predetermined area;
A detection history storage unit that stores a detection history table indicating a detection history of the physical quantity;
A first communication unit that performs wireless communication with the wireless master station;
The detection result of the environmental physical quantity detection unit is acquired every time the first time elapses, and it is determined whether or not data transmission to the wireless master station is necessary based on the acquired detection result and the detection history table. When it is determined that it is necessary, the detection data including the detection result is transmitted to the wireless master station via the first communication unit, and the detection result and the current A first control unit that stores time in association with the detection history table,
The wireless master station is
A second communication unit that performs wireless communication with the wireless sensor;
A third communication unit that communicates with other devices via a predetermined network;
A reception history storage unit for storing a reception history table indicating a reception history of the detection data from the wireless sensor;
When the detection data is received via the second communication unit, the received detection data is transmitted to the other device via the third communication unit, and the received detection data and the current time are A second control unit that associates and stores in the reception history table,
The second control unit, when an elapsed time after storing the detection data in the reception history table exceeds a time obtained by adding a second time shorter than the first time to the first time The detection data satisfying a predetermined condition is read from the reception history table, data based on the read detection data is transmitted to the other device via the second communication unit, and the transmitted data and the current time The time before the second time is associated and stored in the reception history table.
A wireless communication system. The wireless master station performs wireless communication with a plurality of wireless sensors,
In each of the wireless sensors,
The first control unit stores identification information of the wireless sensor in the detection data transmitted to the wireless master station,
In the wireless master station,
The reception history storage unit stores a reception history table corresponding to each wireless sensor,
In the reception history table corresponding to any one of the wireless sensors, the second control unit is a time obtained by adding the second time to the first time after storing the detection data. Is detected, the detection data satisfying a predetermined condition is read from the reception history table, data based on the read detection data is transmitted to the other device via the second communication unit, and the transmitted data and , The time before the second time from the current time is associated and stored in the reception history table,
The wireless communication system according to claim 1. The first control unit of the wireless sensor acquires a detection result of the environmental physical quantity detection unit at every elapse of the first time, and adds or adjusts a predetermined adjustment value to the acquired detection result. Determining the necessity of data transmission to the wireless master station based on the value obtained by this and the detection history table,
The second control unit of the wireless master station, when the elapsed time after storing the detection data in the reception history table exceeds the time obtained by adding the second time to the first time, Detection data satisfying a predetermined condition is read from the reception history table, the adjustment value is added to or subtracted from the sensor data included in the read detection data, and data obtained as a result is stored in the second data Transmitting to the other device via the communication unit, and associating the transmitted data with the time before the second time from the current time, and storing it in the reception history table;
The wireless communication system according to claim 1. An environmental physical quantity detector that detects a predetermined physical quantity relating to the environment of a predetermined area;
A detection history storage unit that stores a detection history table indicating a detection history of the physical quantity;
A first communication unit that performs wireless communication with a wireless master station;
The detection result of the environmental physical quantity detection unit is acquired every time the first time elapses, and it is determined whether or not data transmission to the wireless master station is necessary based on the acquired detection result and the detection history table. When it is determined that it is necessary, the detection data including the detection result is transmitted to the wireless master station via the first communication unit, and the detection result and the current A first control unit that associates the time and stores the time in the detection history table,
A wireless sensor characterized by the above. A wireless communication method between a wireless sensor and a wireless master station,
The wireless sensor is
Detect a certain physical quantity related to the environment of a certain area,
Every time the first time elapses, the necessity of data transmission to the wireless master station is determined based on the physical quantity detection result and the detection history table indicating the physical quantity detection history, and data transmission is necessary. If it is determined, the detection data including the detection result is transmitted to the wireless master station, and the detection result and the current time are associated with each other and stored in the detection history table regardless of the determination result. ,
The wireless master station is
When the detection data from the wireless sensor is received, the received detection data is transmitted to another device connected via a predetermined network, and the received detection data is associated with the current time to detect the detection. Store it in the reception history table showing the data reception history,
When the elapsed time since the detection data is stored in the reception history table exceeds the first time plus a second time shorter than the first time, a predetermined condition is set from the reception history table. The detection data satisfying the above condition is read, and the data based on the read detection data is transmitted to the other device, and the received data is associated with the time before the second time from the current time. Store in history table,
A wireless communication method.

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