KR102406689B1 - Communication System based on LoRa Protocol with Improved Security and Communication Method using the same - Google Patents

Abstract

A LoRa protocol-based communication system and a communication method using the same are provided. According to the present invention, it is possible to efficiently and stably transmit data through a protocol for IoT sensors that can transmit sensor information transmitted from various sensors using the LoRa protocol.

Description

Communication System based on LoRa Protocol with Improved Security and Communication Method using the same}

The present invention relates to a LoRa protocol-based communication system for the Internet of Things, and provides a communication system suitable for IoT devices including various sensors by performing encryption on a transmitted data packet frame in a predetermined manner, while providing a secure It relates to a communication system with improved performance and a communication method using the same.

Recently, with the development of sensors, communication, embedded systems, etc., the Internet of Things (IoT) is being applied to various fields. Although the Internet of Things needs to exchange information between various types of sensors, sensors are required to have a wide range of coverage for the convenience of network configuration, as they are driven by batteries in most cases. A communication protocol made according to the above requirements is a LoRa (Long Range, LoRa) protocol. The LoRa protocol has a wide range of coverage and uses radio frequencies in the Sub Giga Hz (400 MHz to 900 MHz) band as a low-power wireless platform. Since the Internet of Things does not require high-speed real-time communication due to its characteristics, the LoRa protocol can set the data transmission time to transmit data every few seconds to several tens of minutes as needed. It has a lower transmission speed than LTE or 5G communication, which is widely used. As described above, the LoRa protocol can run the network for several months to years without battery replacement due to its low transmission speed and long transmission interval, and because it uses a transmission frequency of a relatively lower MHz band than the recently commercialized LTE or 5G. Data can be transmitted/received to a sensor installed in an arbitrary location at a distance of several hundred meters or more than 10 km without a repeater. Due to these characteristics, the LoRa protocol is widely adopted in the recently built Internet of Things system. However, the LoRa protocol only provides basic guidelines for transmitting data collected from various sensors. It does not support a communication protocol suitable for the Internet of Things (IoT) device.

Korean Patent Document No. 10-1783834 (2017.09.26) Korean Patent Publication No. 10-2019-0079917 (2019.07.08) Korean Patent Document No. 10-1663994 (2016.10.04) Korean Patent Publication No. 10-2016-0116716 (2016.10.10) Korean Patent Publication No. 10-2017-0111768 (2017.10.12) Korean Patent Publication No. 10-2018-0058415 (2018.06.01)

An object of the present invention is to provide a system and method capable of efficiently and stably transmitting data by inventing a protocol for an IoT sensor that can transmit sensor information transmitted from various sensors using the LoRa protocol.

Another object of the present invention is to provide a system and method capable of smoothly performing communication with a sensor or device installed in a site where an existing communication network is not provided.

In addition, an object of the present invention is to provide a system and method capable of optimized communication according to the type and number of sensors installed in the field by flexibly changing the size of the data field according to the type and number of sensors provided in the system. There is this.

Another object of the present invention is to provide a system and method capable of real-time on-site monitoring in a control server by mapping and displaying sensor information transmitted from a corresponding sensor or device to a location where a sensor or device is installed in real time.

An embodiment of the present invention for solving the above problems is installed at a preset location, configured to transmit sensor information at the installed location, and a sensor 10 or a unique device to which a unique sensor ID is assigned The device 20 to which an ID is assigned, the sensor 10 or the device 20 performs wireless communication through a serial communication protocol, and the sensor 10 or the device 20 transmits the is configured to receive sensor information, converts the received sensor information into first conversion information according to the LoRa protocol, a sensor ID or device ID included in the sensor information, and a time at which the sensor information is transmitted The IoT RF module 30, which generates an encryption key based on a combination of information, is configured to receive the first conversion information and the encryption key transmitted from the IoT RF module 30, and transmitted from the IoT RF module 30 The second conversion transmitted from the gateway 40 and the gateway 40, which converts the encryption key and the first conversion information to be converted into second conversion information according to the TCP/IP protocol or TCP/IP Modbus protocol and a control server (50) configured to receive information.

In one embodiment, the data packet frame used in the TCP/IP protocol and the TCP/IP Modbus protocol includes a start byte, a frame length field, a serial number field, a transaction number field, a current time field, a command field, and a data field. , a cyclic redundancy check (CRC) field and an end byte.

In an embodiment, information on a length from the serial number field to the end byte is recorded in the frame length field, the sensor ID or the device ID is recorded in the serial number field, and the transaction number field The ID of one or more of the sensor, device, and IoT RF module that has passed from the sensor 10 or device 20 to which the initial sensor information is transmitted until it is transmitted to the control server 50 is recorded, or the first sensor information is transmitted The number of hops from the sensor 10 or device 20 to being transmitted to the control server 50 may be recorded, and the year, month, day, hour, minute and second of the time when the sensor information was transmitted may be described in the current time field.

In one embodiment, the sensor 10 is any one selected from the group consisting of a PIR sensor, an occupant counter sensor, a CO ₂ sensor, a dust sensor, a temperature/humidity sensor, a CO sensor, an illuminance sensor, a temperature sensor, and a smoke sensor. As described above, the size of the data field may be flexibly adjusted according to the type and number of sensors provided in the communication system, and command information described in the command field.

In an embodiment, the control server 50 includes the sensor ID, the device ID, a unique IoT RF module ID assigned to each IoT RF module 30 , and a unique gateway assigned to each gateway 40 . It may further include a registration module 54 in which the ID is input and the installation positions of the sensor 10 and the device 20 are registered.

In an embodiment, the control server 50 includes a mapping module 53 that displays the sensor information at an installation location of the sensor 10 or the device 20 described in the serial number field and the sensor Further comprising a warning signal generating module 55 for generating a warning signal when the information meets a predetermined criterion so that the generated warning signal is transmitted to the gateway 40, the IoT RF module 30 is a notification module Further including ( 35 ), when the warning signal is received from the control server 50 , the notification module 35 may output a notification signal. The gateway 40 and the control server 50 perform wired communication, and use the TCP/IP protocol or the TCP/IP Modbus protocol method to establish a wireless communication network established at a location where the control server 50 is provided. It may further include a fourth communication module 60 for performing wireless communication with the gateway 40 and the control server 50 through the.

In one embodiment, the serial communication protocol may be an RS-485 Modbus protocol.

In one embodiment, as a communication method using the above-described communication system, (a) the sensor 10 or the device 20, transmitting sensor information at a location where each sensor or each device is installed , (b) the conversion module 32 of the IoT RF module 30 receiving the sensor information transmitted in the step (a), and converting the received sensor information into first conversion information according to the LoRa protocol, (c) generating, by the encryption module 33 of the IoT RF module 30, an encryption key based on a combination of a sensor ID or device ID included in the sensor information and time information at a time when the sensor information is transmitted; (d) the gateway 40 converts the information including the first conversion information and the encryption key into second conversion information according to the TCP/IP protocol or the TCP/IP Modbus protocol, It provides a communication method, comprising the steps of transmitting the second conversion information and (e) the control server 50 receiving the second conversion information transmitted in the step (d).

In one embodiment, before step (a), (a0) the sensor ID of the sensor 10 and the device ID of the device 20 are registered in the registration module 54 of the control server 50 Steps, (a1) the control server 50 transmitting a data packet frame including a connection information exchange command code to the gateway 40, and (a2) in response to the command transmitted in the step (a1), The step of the sensor 10 or the device 20 transmitting sensor information, (a3) the sensor information transmitted from the sensor 10 or the device 20, the IoT RF module 30 and the gateway The sensor information having the data packet frame structure in step (a1) is transmitted to the control server 50 through (40), and (a4) in the step (a3), the sensor information is transmitted to the control server 50 ) may further include the step of determining the normal connection state or the abnormal connection state according to the presence or absence of transmission.

In one embodiment, the case in which sensor information is transmitted to the control server 50 in step (a4) is a normal connection state, and a case in which sensor information is not transmitted to the control server 50 is an abnormal connection state. , when it is determined that the connection is abnormal, (a5) the control server 50 may further include transmitting a data packet frame including a reconnection information exchange command code to the gateway 40 .

In one embodiment, the step (a5) may be a step repeatedly performed every preset period.

The present invention can transmit data efficiently and stably by inventing a protocol for IoT sensors that can transmit sensor information transmitted from various sensors using the LoRa protocol.

In addition, according to the present invention, communication with a sensor or device installed in a field where an existing communication network is not provided is performed smoothly.

In addition, according to the present invention, the size of the data field is flexibly changed according to the type and number of sensors provided in the system, so that communication optimized according to the type and number of sensors installed in the field is possible.

In addition, according to the present invention, real-time on-site monitoring in the control server is possible by mapping and displaying sensor information transmitted from a corresponding sensor or device to a location where a sensor or device is installed in real time.

1 is a schematic block diagram for explaining a communication system according to the present invention.
FIG. 2 is a block diagram illustrating the communication system of FIG. 1 in more detail.
3 is a view for explaining a type of sensor provided in the communication system of FIG. 1 and a module in which the sensor is installed.
4 is a diagram for explaining an example of a request packet and a response packet according to the RS-485 Modbus protocol used for mutual communication in the communication system according to the present invention.
5 is a diagram for explaining the structure of a data packet frame according to the TCP/IP protocol used for mutual communication in the communication system according to the present invention.
FIG. 6 is a diagram for explaining a command written in a CMD field of the data packet frame of FIG. 5 .
7 is a diagram for explaining a data field of a data packet frame used to exchange interconnection information.
8 is a diagram for explaining a data field of a data packet frame used to exchange reconnection information with each other.
9 is a diagram for explaining a data field of a data packet frame used to set a sensor or device.
10 is a diagram for explaining a data field of a data packet frame used to collect data from a sensor or a device.
11 is a diagram for explaining a data field of a data packet frame collected from a plurality of sensors provided in the system.
12 and 13 are diagrams for explaining a data field of a data packet frame used for reset and factory reset, respectively.

In some cases, well-known structures and devices may be omitted or shown in block diagram form focusing on core functions of each structure and device in order to avoid obscuring the concept of the present invention.

Throughout the specification, when a part is said to "comprising or including" a certain component, it does not exclude other components unless otherwise stated, meaning that other components may be further included. do. In addition, terms such as “…unit”, “…group”, and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. have. Also, "a or an", "one", "the" and like related terms are used differently herein in the context of describing the invention (especially in the context of the following claims). Unless indicated or clearly contradicted by context, it may be used in a sense including both the singular and the plural.

In describing the embodiments of the present invention, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

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

LoRa protocol based communication system

1 and 2, a communication system according to an embodiment of the present invention will be described.

The communication system according to the present invention includes a sensor 10 , a device 20 , an IoT RF module 30 , a gateway 40 , and a control server 50 .

The sensor 10 may be installed at a preset location in the field, and each of them is configured to transmit different sensor information according to a sensor type while a unique sensor ID is assigned. When it is assumed that the site where the sensor 10 is installed is a construction site of an assembly building, the sensor 10 is preferably provided for each household, for example, it may be installed on the ceiling surface, wall surface and doorway of each household. .

The sensor 10 is, for example, an infrared human body detection (Passive Infrared, PIR) sensor, an occupant counter sensor, a CO ₂ sensor, a dust sensor, a temperature/humidity sensor, a CO sensor, an illuminance sensor, a temperature sensor, and a smoke sensor. It may be any one or more selected from among.

Infrared human body detection sensor transmits human body information, occupant counter sensor transmits occupant counter information, CO ₂ sensor transmits CO ₂ concentration information, dust sensor transmits dust concentration information, and temperature/humidity sensor transmits Temperature/humidity information is transmitted, CO concentration information is transmitted from the CO sensor, illuminance information is transmitted from the illuminance sensor, temperature information is transmitted from the temperature sensor, and smoke concentration information is transmitted from the smoke sensor.

Information transmitted from each sensor is transmitted to the control server 50 through the IoT RF module 30 and the gateway 40, and through this, the sensor information of each sensor installation location is checked in real time on the control server 50 side This may be possible.

The device 20 may also be installed at a preset location in the field, and each of them is configured to transmit different information according to a device type while a unique device ID is assigned thereto.

For example, the device 20 may include a beacon (B) and a location recognition dedicated device (T) provided in the construction site.

In the so-called apartment construction site, it is preferable that a plurality of beacons (B) are provided for each household. The location of the beacon (B) in each household may be located inside the wall pad, and may be buried together when concrete is poured inside each household. Mainly, by embedding the beacon (B) in the wall located in the center of each household, it is desirable to arrange the beacon (B) and the location recognition-only device (T) so that wireless communication with each other is possible no matter where the worker is at least in a specific household do.

A unique beacon ID is given to each beacon (B), and in order to distinguish the positions of a plurality of beacons (B), the beacon ID needs to be registered and stored in the registration module 54 of the control server 50 in advance and stored and managed. there is This process is preferably performed collectively through a separate beacon ID granting device.

The beacon (B) may be divided into a unit household location beacon, an entrance location beacon, an elevator hall location beacon, a basement location beacon, etc., based on the installation location in the collective building. A unit household location beacon means a beacon installed in each individual unit household (meaning it is buried in a wall pad or a wall located in the center of each household), and an entrance location beacon is a beacon installed on the first floor entrance side of each building. means

Here, 'entrance' means the hoist entrance arranged in each building. It is common for workers, construction equipment, and materials to move using a hoist, and after the hoist entrance, it is linked with the elevator hall location beacon so that the movement of the worker can be identified. However, it can be placed at any suitable installation location within the house other than the hoist entrance. The hoist entrance may be located separately from the east entrance, and the east entrance may have a structure connected to the stairwell. At this time, a separate location recognition dedicated device (T) may be provided at the entrance and exit.

The elevator hall location beacon means a beacon installed on each floor of the elevator hall. Here, in addition to the elevator hall location beacon, a separate beacon may be provided in the middle of the stairway connecting each floor. Workers frequently move through the stairwell, and if the distance between the stairwell and the elevator hall is relatively long, it may be difficult to check the movement of the workers moving to the stairwell. It may be provided for each stairway connecting the floors (meaning that it is provided in the middle of each floor).

A basement location beacon means a beacon installed in the basement or underground parking lot.

Here, one basement location beacon may be disposed in each preset area within the basement floor, and these may be disposed so that a blind spot in which a signal of beacon information generated from an individual basement location beacon is not received is not generated. The basement location beacon may be embedded in the floor or ceiling surface of the basement. Alternatively, it may be embedded in columns, beams, etc. disposed in the basement.

The location recognition dedicated device (T) is a personal terminal configured to be able to receive beacon information from a beacon (B) in a nearby location. It may be attached to the safety helmet of the worker in the form of a wearable device that the worker can easily wear, and may further include a separate strong attachment device to be attached to and maintained on the side of the construction equipment and hoist. The location recognition dedicated device (T) is also, like the beacon (B), a unique location recognition dedicated device ID is assigned to each worker or is attached to the construction equipment. The location recognition dedicated device T generates data including location recognition dedicated device ID based on the beacon information. That is, data having a preset data structure is generated by collecting beacon information, and the data generated by the location recognition dedicated device T is transmitted to the IoT RF module 30 . Here, the location recognition dedicated device (T) may be a tracker, but is not particularly limited thereto, and mobile devices such as smartphones, tablet PCs, and laptops having a GPS function may also correspond to this.

The location recognition dedicated device T can be conceptually divided into the following three types. First, an exclusive device for location recognition for workers possessed by the operator, a device for location recognition for equipment provided in the construction equipment itself, a device for location recognition for drivers possessed by a driver who operates construction equipment, and fixed installation at a preset location It is classified as a dedicated device for location recognition. Here, the fixed location recognition dedicated device may be located on the hoist side of each building, and when the material is moved to a specific entrance by the fixed location recognition dedicated device, the movement information of the material can be grasped.

The location recognition dedicated device T includes, for example, a signal receiving module 21, an arithmetic processing module 22, a GPS sensor 23a, a gyro sensor 23b, an acceleration sensor 23c, and an altitude sensor 23d. The sensor module 23 including one or more of the group consisting of a first notification module 24 , a signal transmission module 25 and an emergency call button 26 are included.

The signal receiving module 21 performs a function of receiving beacon information transmitted from the beacon (B). The signal receiving module 21 is configured to receive beacon information in a BLE (Bluetooth Low Energy, BLE) method. The signal reception module 21 is configured to receive the beacon information from the beacon B at a period of a first preset time, and in one embodiment is configured to receive the beacon information in a period of 20 seconds. When the location recognition dedicated device T is not adjacent to the beacon B, there may be a section in which the beacon information cannot be received. To prevent this, the beacon (B) is preferably installed throughout the construction site. In addition, when the signal receiving module 21 does not receive the beacon information, it is preferably configured to receive the GPS information from the GPS sensor 23a. That is, the beacon information or GPS information may be received by the regular signal receiving module 21 .

The arithmetic processing module 22 performs a function of generating or converting data based on the beacon information received by the signal receiving module 21 and the sensor information transmitted from the sensor module 23 . The arithmetic processing module 22 is configured to receive beacon information from the signal receiving module 21 and to receive sensor information from the sensor module 23, and generates data by processing the beacon information and the sensor information in a preset manner. do. In this regard, a plurality of location recognition dedicated devices (T) may be located at the construction site, and when all information sensed or received by each location recognition dedicated device (T) is transmitted to the IoT RF module 30, the system Overall, overload problems can occur. Accordingly, the data is processed to have a specific data structure and then transmitted to the IoT RF module 30 . At this time, the specific data structure is configured in the form of TLV (Time, Length, Value) and has a size less than a preset size (preferably less than 50 bytes), and the specific data structure consists only of information optimized for the construction site.

The signal transmission module 25 refers to a communication module that receives data generated by the arithmetic processing module 22 and transmits it to the IoT RF module 30 . At this time, the signal transmission module 25 may be configured to transmit data to the IoT RF module 30 at a preset second period of time, and preferably may be configured to transmit data at a period of 2 minutes.

The sensor module 23 includes a GPS sensor 23a, a gyro sensor 23b, an acceleration sensor 23c, and an altitude sensor 23d.

The GPS sensor 23a is configured to perform outdoor positioning of the location recognition exclusive device T at a preset third time period, and transmit GPS information to the calculation processing module 22 . This is because the location where beacon information is not received is highly likely to be outside, and GPS information may be received from outside. Alternatively, a GLONASS sensor that performs outdoor positioning in the GLONASS method may be applied.

The gyro sensor 23b and the acceleration sensor 23c are configured to output motion information of the location recognition dedicated device T. The movement information may mean step information (meaning gait) of the operator, and if the step information is not 0, it means that the operator is currently moving. When the step information is 0, it means that the current operator is not moving, and there is a possibility that the operator's safety abnormal situation has occurred. A separate call module (not shown) may be built-in to the location recognition dedicated device T, and through the call module, the manager can make an emergency call with the operator in the above situation. The motion information may mean work information of construction equipment (eg, rotation angle of a tower crane).

The altitude sensor 23d is configured to output altitude information. The altitude information may be the height from the ground of the construction site to the location of the location recognition-only device (T). In the present invention, an altitude sensor having an error within ±3 m may be applied.

The calculation processing module 22 performs a function of generating a warning signal based on sensor information (GPS information, motion information, altitude information) output from the sensor module 23, and when the sensor information meets a preset criterion Generates a warning signal.

For example, when the movement information output from the sensor module 23 is not observed for more than a preset time (that is, when the step information is 0), there is a physical abnormality in the operator to which the position recognition dedicated device T is attached or carried. When it is deemed that the first warning signal is generated, and the altitude information output from the sensor module 23 includes information that changes from the first altitude to a second altitude lower than the first altitude within a preset time (that is, the position When the recognition-only device falls), a second warning signal may be generated by considering that a fall risk has occurred.

When a warning signal is generated by the arithmetic processing module 22, a notification signal such as being transmitted to the first notification module 24 to emit light or to output a sound is output from the location recognition dedicated device T. In addition, it is also possible to monitor the warning signal generation history is transmitted to the control server 50 through the IoT RF module 30 in real time.

When a warning signal is generated by the arithmetic processing module 22 , the data of the corresponding location recognition dedicated device T is immediately transmitted to the IoT RF module 30 . The default setting is that data is collected at a first time period and transmitted to the IoT RF module 30 at a second time period. It can be used as a means to inform the situation. Through this, the manager can determine the location of the location recognition dedicated device (T) where the warning signal is generated, and then check the structure and safety of the operator. That is, it performs a function of immediately and forcibly transmitting data transmitted to the IoT RF module 30 to the IoT RF module 30 in a second period of time.

In addition, the location recognition dedicated device (T) of the present invention is provided with an emergency call button 26, and when the operator presses the emergency call button, the data of the location recognition dedicated device (T) is transferred to the IoT RF module 30 It is configured to be transmitted immediately. The default setting is that data is collected at a first time period and transmitted to the IoT RF module 30 at a second time period, but when the operator detects an abnormality in safety or health, by operating the emergency call button, It can be used as a means to notify the emergency situation. Through this, the manager can determine the location of the location recognition dedicated device 20 at which the emergency call button 26 is pressed, and then check the structure and safety of the operator. That is, it performs a function of immediately and forcibly transmitting data transmitted to the IoT RF module 30 to the IoT RF module 30 in a second period of time. The emergency call button 26 may be provided with two or more buttons, and only when two or more buttons are simultaneously pressed, data may be immediately transmitted to the IoT RF module 30 . Through this, a phenomenon in which the emergency call button 26 is malfunctioned can be prevented.

The IoT RF module 30 of the present invention is installed in one case together with the sensor 10 or the device 20 to receive information transmitted from the sensor 10 or the device 20, and collect the received sensor information. It is converted into the first conversion information according to the (LoRa) protocol and transmitted to the gateway 40 . In another embodiment, the IoT RF module 30 is provided separately from the sensor 10 or the device 20 to receive information transmitted from the sensor 10 or the device 20 .

The IoT RF module 30 includes a first communication module 31 performing wireless communication with the sensor 10 or device 20 through a serial communication protocol, and information received by the first communication module 31 . to the first conversion information, the conversion module 32 for generating an encryption key in a preset manner, and the gateway 40 and TCP/IP protocol or TCP/IP Modbus protocol to communicate and a second communication module (34). The serial communication protocol may be an RS-485 Modbus protocol.

RS-485 Modbus protocol is a communication protocol for serial communication that can transmit and receive data 1 bit at a time. . RS-485 Modbus protocol transmits/receives data in a half-duplex method. Normally, the maximum communication distance is about 1.2km, and the maximum communication speed is about 10Mb/s. The distance is shortened to 12 m.

A data packet frame according to the RS-485 Modbus protocol used for wireless communication between the sensor 10 or the device 20 - the first communication module 31 will be described in more detail with reference to FIG. 4 .

FIG. 4 is a diagram for explaining a data packet frame according to the RS-485 Modbus protocol between the resident counter sensor and the first communication module 31 by taking the sensor 10 as an occupant counter sensor as an example.

When the first communication module 31 transmits a request packet consisting of an STX header, an ID number field, a command field, and an EXT flag to the sensor 10 or device 20, the sensor or device performs a corresponding command to perform the STX header , ID number field, response field, identification code field, accumulated value field, signal output field, counter recognition field, button press field, sensor status field, the first communication module (31) send to

The STX header of the request packet is a part indicating the start of the request packet and has a size of 1 byte, and the ID number field corresponds to the sensor ID of the sensor 10 and the device ID of the device 20 requesting a response, and has a size of 4 bytes. The command field has a size of 3 bytes, and in the case of a “status inquiry” command, the command of “BTR” is written in the command field, and the EXT flag is a part indicating the end of the request packet and has a size of 1 byte. That is, the request packet has a total size of 9 bytes, and when it is desired to inquire the state of the sensor whose sensor ID is “0000”, a request packet of [0000BTR] may be transmitted to the sensor 10 or the device 20.

The STX header of the response packet indicates the start of the response packet and contains 1 byte of information.

In the ID number field, the sensor ID of the responding sensor 10 or the device ID of the device 20 is written in a size of 4 bytes.

The response field is a part according to the command of the request packet, and in the case of a command of “status inquiry”, a response of “BTW” is written in the response field as a response.

In the identification code field, "," is written as a part for classifying the values written in the subsequent accumulated value field, signal output field, counter recognition field, button press field, sensor state field, person limit field, etc.

The cumulative value field includes a cumulative entry value field in which the cumulative number of entry and exit counted by the visitor counter sensor is recorded, a cumulative exit value field in which the cumulative number of exits is recorded, and the current number of people in the space where the counter sensor is installed. It includes fields and each 5 bytes of information is described.

In the signal output field, information on which line to communicate through (RS-485 Modbus protocol communicates through two communication lines) is written in the size of 1 byte each.

In the counter recognition field, the set value of the visitor counter sensor has a size of 1 byte and is described.

In the button press field, the value of whether the button of the counter sensor is operated has a size of 1 byte and is described.

In the sensor status field, the value of the counter sensor status has a size of 1 byte and is described.

In the occupancy limit field, the maximum occupancy setting value in the space where the counter sensor is installed is written in the size of 1 byte.

The reserve field is a field to which a data value can be added as needed, and information of 1 byte can be written in each.

That is, the response packet has a total size of 43 bytes, and when a status inquiry request packet called [0000BTR] is transmitted from the first communication module 31, the sensor 10, for example, [0000BTW,00030,00006,00024,1] ,0,2,1,0,20,0,0] may be transmitted to the first communication module 31 . The above response packet is a response packet according to the sensor status request of the sensor with sensor ID "0000". The cumulative number of entering is 30 and the cumulative number of leaving is 6, so the current number of people is 24, and A response packet is sent, the counter sensor is set with the set value of No. 2, the button is operating, the sensor state is normal, the maximum number of people set is 20, and there are two reserve fields. it means.

The above request packet and response packet have been described as an example, and although the packet having the same structure is applied according to the RS-485 Modbus protocol, it goes without saying that the detailed data of the packet may vary depending on the type of sensor and the request command.

The conversion module 32 is configured to convert information (sensor information) received from the sensor 10 or device 20 into first conversion information according to a LoRa protocol.

The LoRa protocol is a protocol developed for the Internet of Things, which enables long-distance communication with low power, can attach multiple sensors to a Dail node, and provides an advanced encryption standard. In addition, the LoRa protocol has the advantage that it can transmit data over 10 km without a repeater (gateway), so it can cover a wide area by installing only a small number of repeaters to build a network. In addition, since the LoRa protocol transmits data in a chirp spread spectrum method, data can be transmitted with low power, and it is robust against multipath and has a wide range of coverage.

The conversion module 32 converts the sensor information received from the sensor 10 or the device 20 into first conversion information so as to conform to the LoRa protocol, and the LoRa protocol is a well-known communication protocol, so a detailed description thereof will be omitted. On the other hand, in order to restore the first converted information converted through the LoRa protocol, a chirp signal used for data transmission is required, which has a strong advantage against interference with external signals or security.

The encryption module 33 generates an encryption key in a preset manner. The encryption module 33 according to the present invention includes the sensor ID or device ID of each sensor included in the information transmitted from the sensor 10 or the device 20, and the sensor information from the sensor 10 or the device 20. An encryption key is generated based on the combination of time information at the time of transmission.

In one example, the sensor ID and device ID may be composed of 4 bytes of data, and the time information may be composed of 6 bytes of data. In another example, the last 2 bytes of the sensor ID and the device ID and the first 4 bytes of the time information can be combined to generate a total encryption key of 6 bytes. However, unless specifically limited thereto, it will be said that any encryption algorithm may be applied as long as an encryption key is generated based on a combination of a sensor ID or device ID and time information.

The algorithm for generating the encryption key by the encryption module 33 is registered in the control server 50 in advance, and the control server 50 decrypts the transmitted information using the previously registered encryption algorithm to decrypt the information. It is possible to restore

The encryption key generated by the encryption module 33 is transmitted to the gateway 40 together with the first conversion information, so that in order to restore information transmitted through the gateway 40, restoration of the chirp spread spectrum applied in the LoRa protocol You need a chirp signal for , and an encryption key to decrypt. That is, the data transmitted in the present invention has advantages in that security is improved through double encryption and is robust against external signals or interference.

In another example, without generating an encryption key by the encryption module 33, only the first conversion information may be transmitted to the gateway 40, and in another example, encryption is performed according to the Advanced Encryption Standard (AES). may be performed.

This may be performed according to the setting of the encryption module 33 of the IoT RF module 30, for example, when the encryption setting is “0000”, data is transmitted without performing encryption, and when the encryption setting is “0001” Encrypted data is transmitted by performing encryption using the advanced encryption standard method (AES128, domestic standard). When the encryption setting is “0002”, the above encryption key is generated and data can be transmitted with the first conversion information. have.

The second communication module 34 transmits the information including the first conversion information converted by the conversion module 32 and the encryption key generated by the encryption module 33 to the gateway 40 .

The gateway 40 is configured to receive the first conversion information and the encryption key transmitted from the second communication module 30 .

The gateway 40 may be provided at a main point, for example, a distribution board, and at a construction site, the distribution board is a device for temporarily supplying electricity, and can be moved according to the progress of the construction, thereby providing a stable electricity supply at all times. can receive

The gateway 40 communicates with the control server 50 through a TCP/IP protocol or a TCP/IP Modbus protocol, and the structure of a data packet frame performed for communication may have the structure shown in FIG. 5 . To this end, the gateway 40 converts the received encryption key and the first conversion information into second conversion information to conform to the TCP/IP protocol or the TCP/IP Modbus protocol.

FIG. 5 is a diagram for explaining a data packet frame according to the TCP/IP protocol between the gateway 40 and the control server 50 .

A data packet frame according to the TCP/IP protocol includes a Start Byte, Frame Length field, Serial No. field, Transaction No. field, Current Time field, It may consist of a command (CMD) field, a data (DATA) field, a CRC field, and an end byte.

In the start byte, information indicating the start of data to be transmitted has a size of 1 byte and is described, for example, a value of 0x02 may be described.

In the frame length field, information on the length from the serial number field to the end byte is written in a size of 2 bytes.

In the serial number field, the unique ID of the sensor 10 or the device 20 to which the first information is transmitted is written in a size of 4 bytes, for example, in the order of device identifier / manufacturing year / product manufacturing order written in two digits. Data with a size of 4 bytes is described.

In the transaction number field, each ID that has passed from the sensor 10 or device 20 from which the initial information is transmitted to the gateway 40 is described in a size of 4 bytes or the number of hops.

In the current time field, information about the time when the information was generated, specifically, information of 6 bytes in size consisting of year, month, day, hour, minute, and second is described. As an example, time information of 10:56:21 on July 17, 19 in the form of a HEX code may be written as 13 07 11 0A 36 15 in the current time field.

Command information is written in the CMD field. Specifically, commands such as "Request Status Information", "Status Information Response", "Measurement Value Request", "Measured Value Receive", "Write Settings", and "Read Settings" described as information.

In the data field, accompanying information according to the command written in the CMD field is described, the size is flexibly adjusted according to the type of sensor provided in the communication system and command information described in the command field.

In the CRC field, information for error checking is described, and a CRC16 code of 2 bytes from the start byte to the data field is described.

The end byte is a part indicating the end of data, and 1 byte of information having a value of 0x03 may be written. The above-described values starting with 0x (ie, 0x02, 0x03, etc.) mean hexadecimal values.

6 is a diagram for explaining a command that can be written in a CMD field of a data packet frame according to the present invention.

The command code of 0x00 corresponds to a command called Exchange Connection info, and when the corresponding command code is described, connection information is exchanged between the gateway 40 and the control server 50 . 6, the data field included in the data packet frame of the information transmitted from the gateway 40 to the control server 50, and the data packet frame of the information responding from the control server 50 back to the gateway 40 Data fields are shown.

In Data[0], 1 byte of data indicating the state of the dip switch is described, and in Data[1] and Data[2], basic sensor information, specifically temperature/humidity information, and CO information are described, and Data[3] entrant counter information is written in Data[4], human body detection information is written in Data[4], temperature information is written in Data[5], smoke concentration information is written in Data[6], and Data[7] to [10] ] is a preliminary data field for displaying new sensor or device information as needed.

That is, when the data packet frame including the command code of 0x00 is transmitted from the gateway 40 to the control server 50 , the data packet frame having the same structure is transmitted again from the control server 50 to the gateway 40 . That is, the command code 0x00 corresponds to a command for exchanging connection information between the gateway 40 and the control server 50 .

The sensor 10 or device 20 is installed, and in order to transmit and receive information with the control server 50, a connection between both the gateway 40 and the control server 50 must be made, and if the connection information is normally exchanged, the connection between the two This has been done normally. That is, the connection information exchange command is used for checking the connection state of the equipment when the sensor 10 or the device 20 is initially connected.

The command code of 0x0F corresponds to a command called Re-Connect Connection info. When the sensor 10 or the device 20 is initially connected, a data packet frame including a command code of 0x00 is transmitted to check the connection state of the equipment, but the connection information is not initially received from the control server 50, In order to determine whether the connection information is changed due to damage/change of the sensor 10 or the device 20 , a command for reconnection information exchange may be performed.

That is, the reconnection information exchange is used for checking the connection state between the sensor 10 or the device 20 and the control server 50 , and the control server 50 performs the reconnection information exchange with the sensor 10 at a predetermined first time period. ) or by allowing reconnection information exchange with the device 20 to be performed, it is possible to periodically check the connection state.

A data packet frame having the structure shown in FIG. 8 is transmitted from the control server 50 to the gateway 40, and the sensor 10 or device 20 transmits the data packet frame having the structure shown in FIG. 8 to the control server 50 ) will be sent to When the data packet frame is transmitted and received normally, the sensor 10 or device 20 and the control server 50 are normally connected, and the data packet frame including the 0x0F command code in the control server 50 is transmitted, but there is no response or when a data packet frame having a different structure is transmitted, it may be determined that the connection state is disconnected or abnormally connected. As this is repeatedly performed every preset period, it is possible for the control server 50 to check the connection state with the sensor 10 or the device 20 in real time. The preset period may be several tens of seconds to several minutes.

The command code of 0x01 corresponds to a command for setting the type and number of sensors 10 or devices 20 connected to the control server 50 . 9 is a data request packet configuration diagram for setting the sensor 10 or device 20, and a data response packet configuration diagram for setting the sensor 10 or device 20 An example diagram is shown.

The type of the connected sensor 10 or device 20 is determined by the Data[0] and Data[1] fields.

Data[0] and Data[1] fields contain 1 byte of data. For example, Data[0] contains information about the CO ₂ sensor, and Data[1] contains CO sensor, dust sensor, illuminance sensor, and PT. Information about a sensor, an analog sensor, a temperature/humidity sensor, a humidity sensor, and a temperature sensor may be described. For example, if data “00000001” is written in the Data[0] field, it means that the CO ₂ sensor is set, and when data “01010101” is written in the Data[1] field, the CO sensor is not set , meaning that the dust sensor is set, the illuminance sensor is not set, the PT sensor is set, the analog sensor is not set, the temperature/humidity sensor is set, the humidity sensor is not set, and the temperature sensor is set . The types of data described in Data[0] and Data[1] may be changed according to the types of sensors provided in the communication system according to the present invention. In addition, if it is necessary to set a plurality of the same sensor, for example, assuming that two CO ₂ sensors are provided in the communication system according to the present invention, the data "00000011" is written in the Data[0] field, It is also possible for each of the CO ₂ sensors to be set.

That is, in the data packet frame that starts from the sensor 10 or the device 20 and is transmitted to the control server 50 through the gateway 40 according to the type of sensor provided in the communication system according to the present invention, Data[0] and the data described in Data[1] may be different, and the control server 50 sets the sensor 10 or the device 20 in the communication system according to the data described in Data[0] and Data[1]. can

The communication system according to the present invention has a factory reset function together. Specifically, when a data packet frame including a command code of 0xFF is transmitted from the control server 50, the preset sensor 10 or device 20 It is initialized (refer to FIG. 13 ) and the data packet frame including the command code of 0x01 is transmitted again, so that it is possible to set the sensor 10 or the device 20 provided in the corresponding communication system.

The command code of 0x04 corresponds to a command for requesting data collection from the sensor 10 or device 20 connected to the control server 50 .

FIG. 10 shows an example of a data request packet of the sensor 10 or device 20 connected to the control server 50 and a data response packet configuration diagram of the sensor 10 or device 20 .

That is, when the type of sensor 10 or device 20 to be collected is set in the Data[0] and Data[1] fields and transmitted, the gateway 40 transmits from each sensor 10 or device 20 The collected information is transmitted to the control server 50 through the data packet frame structure shown in FIG. That is, in the response packet transmitted to the control server 50, CO2 concentration information is described in Data[0] to [3], CO concentration information is described in Data[4] to [7], and Data[8] to Dust concentration information is described in [11], illuminance information is described in Data [12] to [15], PT information is described in Data [16] to [19], and PT information is described in Data [20] to [23]. Analog information is written, temperature/humidity information is written in Data[24] to [27], temperature information is written in Data[28] to [31], and field values above Data[32] are information on the occupant counter, respectively. , human body detection information, temperature information, smoke concentration information, etc. are described. Subsequent data field values may vary according to the type and number of sensors 10 or devices 20 set in the control server 50 .

In the communication system according to the present invention, each sensor may be provided in plurality. In this case, the collected data is transmitted through the data packet frame shown in FIG. 11 . That is, when three resident counter sensors are provided, each resident counter information is recorded in each field value with three data field values, and when two infrared human body detection sensors, temperature sensors and smoke sensors are provided, each data With two field values, each human body detection information, temperature information, and smoke concentration information may be written in each field value.

The command code of 0x80 corresponds to a command for resetting, and when the data packet frame shown in FIG. 12 is transmitted, the system is re-executed.

Referring to FIG. 2 , the control server 50 includes a third communication module 51 , a coordinate calculation module 52 , a mapping module 53 , a registration module 54 , a warning signal generating module 55 , and a database 56 . ) is included.

The second conversion information may be received from the gateway 40 through the third communication module 51 , and the received second conversion information may be stored in the database 56 .

The coordinate calculation module 52 calculates coordinates (two-dimensional coordinates or three-dimensional coordinates) of the sensor 10 or device 20 included in the data based on the received information. As the coordinate calculation method, a method using an installation location registered in the registration module 54 in advance, a relative coordinate calculation through comparison with the location of the beacon B, and an absolute coordinate calculation method based on GPS information may be used.

The sensor 10 provided in the field is given a unique sensor ID for each sensor, and the device 20 is also given a unique device ID, the sensor ID, the device ID, and the installation location of the sensor 10, the device ( 20) is registered in advance through the registration module 64 . Accordingly, by using the beacon information included in the data, it is possible to calculate the relative coordinates of the location recognition-only device T with respect to the beacon B. Since the beacon information included in the data includes beacon information for a plurality of beacons (B), the current location recognition-only device (T) by calculating the relative coordinates of the location recognition-only device (T) for the plurality of beacons (B) ) can be calculated.

In addition, when the data does not contain beacon information due to the interruption of the communication connection between the location recognition device (T) and the beacon (B), the absolute coordinates of the current location recognition device (T) are calculated based on the GPS information. It is also possible

The mapping module 53 performs a function of mapping the coordinates calculated by the coordinate calculation module 52 to the coordinate system of the field.

When mapping is performed by the mapping module 53, the positions of all sensors 10 and devices 20 provided in the field, and each sensor information are all displayed on one coordinate system and output on a display (not shown) It can be done, and through this, it is possible to monitor the site in real time.

The process performed in the registration module 54 precedes the process used in the communication system of the present invention. The device to be registered in the registration module 54 includes all of the sensor 10 , the device 20 (including a beacon and a location recognition dedicated device), the IoT RF module 30 , and the gateway 40 .

The warning signal generating module 55 generates a warning signal when sensor information included in the data field meets a preset criterion.

For example, when the smoke concentration information transmitted from the smoke sensor is equal to or greater than a preset concentration, it is determined that a fire has occurred at the sensor installation location and a warning signal may be generated. Different reference information for each sensor is stored in advance in the database 56 . When a warning signal is generated by the warning signal generating module 55 , the corresponding information is transmitted to the IoT RF module 30 through the gateway 40 , and the second notification module 35 of the IoT RF module 30 is A notification will be output.

In the database 56, data transmitted from the gateway 40 is stored, that is, location information of the sensor 10 or device 20, state information, SOS information (warning signal), and sensor information sensed by the sensor are stored. . The administrator can not only monitor information in real time, but also check past information using information stored in the database 56 .

In addition, the data stored in the database 56 may be provided in connection with an external system through an API, and it is possible to monitor the construction site by accessing the database 56 from outside the site.

The communication system according to the present invention further includes a fourth communication module (60).

The aforementioned gateway 40 and the control server 50 communicate with each other by wire. The fourth communication module 60 is configured so that wireless communication between the gateway 40 and the control server 50 can be performed through a wireless communication network established at a location where the control server 50 is provided.

For example, the fourth communication module 60 may include an LTE modem, and wireless communication between the gateway 40 and the control server 50 may be performed through an existing LTE communication network.

LoRa protocol-based communication method

First, a process of registering the sensor 10 and the device 20 provided at each site in the registration module 54 of the control server 50 is performed. In some cases, the corresponding process may be omitted.

Next, the control server 50 transmits the data packet frame including the access information exchange command code to the gateway 40 , and the sensor 10 or the device 20 transmits sensor information in response to the transmitted command.

When the sensor information transmitted from the sensor 10 or the device 20 is received by the control server 50, it is determined as a normal connection state and the subsequent data collection process is performed, and the data packet frame that is not received or has a different structure is not received. If received, it is determined that the connection is abnormal, and the control server 50 transmits a data packet frame including a reconnection information exchange command code to the gateway 40 . In response, the sensor 10 or the device 20 transmits the sensor information again, and when the transmitted sensor information is received by the control server 50, it is determined as a normal connection state, and the data is not received or has a different structure When a packet frame is received, it is determined as an abnormal connection state, and a connection re-establishment process of the sensor 10 or device 20 is performed.

The data packet frame including the reconnection information exchange command code may be repeatedly transmitted from the control server 50 at a preset period, through which the connection state with the sensor 10 and the device 20 provided in the system can be checked periodically.

When it is determined that a normal connection state is established, sensor information is transmitted from the sensor 10 or the device 20 .

First, the sensor 10 or device 20 transmits sensor information at the location where each sensor or each device is installed, and the conversion module 32 of the IoT RF module 30 receives the transmitted sensor information , converts the sensor information into the first conversion information according to the LoRa protocol.

Next, the encryption module 33 of the IoT RF module 30 generates an encryption key based on a combination of the sensor ID or device ID included in the sensor information and the time information at the time when the sensor information is transmitted, and the first conversion information and Information including the generated encryption key is transmitted to the gateway 40 .

Next, the gateway 40 converts the information including the first conversion information and the encryption key into second conversion information according to the TCP/IP protocol or the TCP/IP Modbus protocol, and transmits the second conversion information to the control server 50 . information will be sent.

The control server 50 receives the second conversion information, calculates the coordinates of the sensor 10 or the device 20 corresponding to the sensor ID or device ID included in the second conversion information, and then calculates the calculated coordinates. It is mapped to the coordinate system of the site. In addition, each control server 50 maps the sensor information transmitted from the sensor 10 or the device 20 together to a coordinate system, so that an administrator can monitor in real time.

In addition, when the sensor information included in the received second conversion information meets a preset criterion, a warning signal may be generated and transmitted to the gateway 40 again, and accordingly, the second notification of the IoT RF module 30 A notification signal is output from the module 35 so that it is possible to immediately notify a nearby operator.

In the above, the present specification has been described with reference to the embodiments shown in the drawings so that those skilled in the art can easily understand and reproduce the present invention, but these are merely exemplary, and those skilled in the art can make various modifications and equivalents from the embodiments of the present application. It will be appreciated that embodiments are possible. Therefore, the protection scope of the present application should be defined by the claims.

10: sensor
20: device
B: beacon
T: Dedicated device for location recognition
21: signal receiving module
22: arithmetic processing module
23: sensor module
24: first notification module
25: signal transmission module
30: IoT RF module
31: first communication module
32: conversion module
33: encryption module
34: second communication module
35: second notification module
40: gateway
50: control server
51: third communication module
52: coordinate operation module
53: mapping module
54: registration module
55: warning signal generation module
56: database
60: fourth communication module

Claims (12)

a sensor 10 installed at a preset location, configured to transmit sensor information at the installed location, and assigned a unique sensor ID;
It is configured to perform wireless communication with the sensor 10 through a serial communication protocol, and to receive the sensor information transmitted from the sensor 10, and to generate the received sensor information according to a LoRa protocol. 1 converting information into conversion information, and generating an encryption key based on a combination of a sensor ID included in the sensor information and time information at a time when the sensor information is transmitted, the IoT RF module 30;
It is configured to receive the first conversion information and the encryption key transmitted from the IoT RF module 30, and the encryption key and the first conversion information transmitted from the IoT RF module 30 are converted to a TCP/IP protocol or TCP/IP Converting to the second conversion information according to the Modbus (Modbus) protocol, the gateway 40; and
A control server (50) configured to receive the second conversion information transmitted from the gateway (40); includes;
The data field of the data packet frame used in the TCP/IP protocol and the TCP/IP Modbus protocol includes the type and number of sensors 10 provided in the communication system, and the command information described in the command field of the data packet frame. The size is flexibly adjusted according to the
The control server 50 transmits the data packet frame structure including the command code corresponding to the connection information exchange to the gateway 40, and the sensor 10 according to whether information having the data packet frame structure is received. Determining the connection state with
The control server 50,
a mapping module 53 for displaying the sensor information at an installation location of the sensor 10;
A registration module in which the sensor ID, a unique IoT RF module ID given to each IoT RF module 30, and a unique gateway ID assigned to each gateway 40 are input, and the installation location of the sensor 10 is registered (54); and
and a warning signal generating module 55 that generates a warning signal when the sensor information meets a predetermined criterion and transmits the generated warning signal to the gateway 40;
The IoT RF module 30 further includes a notification module 35, and when the warning signal is received from the control server 50, a notification signal is output from the notification module 35,
communication system.
According to claim 1,
The data packet frame used in the TCP/IP protocol and the TCP/IP Modbus protocol includes a start byte, a frame length field, a serial number field, a transaction number field, a current time field, a command field, a data field, and a cyclic redundancy check (CRC). ) field and the terminating byte,
communication system.
3. The method of claim 2,
In the frame length field, information on the length from the serial number field to the end byte is recorded,
The sensor ID is written in the serial number field,
In the transaction number field, IDs of at least one of a sensor and an IoT RF module that have passed from the sensor 10 from which the initial sensor information is transmitted until it is transmitted to the gateway 40, respectively, or the sensor 10 to which the initial sensor information is transmitted ) to the number of hops from which it is transmitted to the gateway 40,
In the current time field, the year, month, day, hour, minute and second of the time when the sensor information is transmitted is written,
communication system.
4. The method of claim 3,
The sensor 10 is
At least one selected from the group consisting of a PIR sensor, an occupant counter sensor, a CO ₂ sensor, a dust sensor, a temperature/humidity sensor, a CO sensor, an illuminance sensor, a temperature sensor, and a smoke sensor,
communication system.
delete delete According to claim 1,
The gateway 40 and the control server 50 perform wired communication,
so that wireless communication with the gateway 40 and the control server 50 is performed through a wireless communication network established at a location where the control server 50 is provided by the TCP/IP protocol or the TCP/IP Modbus protocol method Further comprising a fourth communication module 60,
communication system.
According to claim 1,
The serial communication protocol is RS-485 Modbus protocol,
communication system.
A communication method using the communication system according to claim 1, comprising:
(a) transmitting, by the sensor 10, sensor information at a location where each sensor is installed;
(b) the conversion module 32 of the IoT RF module 30 receiving the sensor information transmitted in step (a), and converting the received sensor information into first conversion information according to the LoRa protocol;
(c) generating, by the encryption module 33 of the IoT RF module 30, an encryption key based on a combination of a sensor ID included in the sensor information and time information when the sensor information is transmitted;
(d) the gateway 40 converts the information including the first conversion information and the encryption key into second conversion information according to the TCP/IP protocol or the TCP/IP Modbus protocol, 2 transmitting conversion information; and
(e) receiving, by the control server 50, the second conversion information transmitted in step (d);
communication method.
10. The method of claim 9,
Before step (a),
(a0) registering the sensor ID of the sensor 10 in the registration module 54 of the control server 50;
(a1) transmitting, by the control server 50, a data packet frame including a connection information exchange command code to the gateway 40; and
(a2) transmitting, by the sensor 10, sensor information in response to the command transmitted in step (a1);
(a3) The sensor information transmitted from the sensor 10 passes through the IoT RF module 30 and the gateway 40, and the sensor information having the data packet frame structure in step (a1) is transferred to the control server ( 50) is sent to; and
(a4) determining the normal connection state or the abnormal connection state according to whether the sensor information is transmitted to the control server 50 in the step (a3);
communication method.
11. The method of claim 10,
A case in which sensor information is transmitted to the control server 50 in step (a4) is a normal connection state, and when sensor information is not transmitted to the control server 50, or a data packet frame in step (a1) A data packet with a structure different from that of the data packet frame structure is transmitted in an abnormal connection state.
If it is determined that the connection is abnormal,
(a5) transmitting, by the control server 50, a data packet frame including a reconnection information exchange command code to the gateway 40;
communication method.
12. The method of claim 11,
The step (a5) is a step that is repeatedly performed every preset period,
communication method.

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