CN103684938B - A kind of industrial bluetooth network system and network-building method - Google Patents

Abstract

The invention discloses an industrial bluetooth network system and a networking method, wherein a bluetooth network system includes a master station and a plurality of slave stations, and each slave station has a network key device for storing encrypted bluetooth security networking filter parameters. Before networking, the Bluetooth master station sets the search and filter parameters according to the piconet ID to ensure that only slave stations that meet the requirements can be searched; the Bluetooth slave station sets the piconet ID as its own device type, and sets Connection filtering parameters to ensure that it can be searched by the master station to which it belongs and only allow the master station to establish a connection with itself. In the networking, the Bluetooth master and slave stations establish ACL links according to the set networking filtering parameters to prevent unauthorized or illegal Bluetooth devices from joining the network. After networking, the data communication in the Bluetooth piconet is encrypted with a sequence cipher algorithm to prevent illegal devices from monitoring. The invention improves the safety, robustness, maintainability and flexibility of the network.

Description

An industrial bluetooth network system and networking method

technical field

The invention relates to a wireless network networking technology, in particular to a bluetooth network system and a networking method suitable for industrial environments.

Background technique

With the rapid development and maturity of wireless technology, more and more industrial sites use wireless technology as a supplement to wired technology, especially in some occasions where wiring is inconvenient, such as communication between moving or rotating equipment, across rivers, Wireless technology is widely used for communication between devices across roads or railways. The use of wireless technology has the following advantages: simple wiring, long system life, and high reliability. The wireless technologies currently used in industrial occasions include WIFI, Bluetooth, ZigBee, etc. WIFI is suitable for long-distance high-speed data transmission, Bluetooth is suitable for short-distance medium-speed data transmission with high reliability requirements, and ZigBee is suitable for For low-speed multi-node data transmission, engineers can use different wireless technologies according to the needs of different application scenarios.

Bluetooth is a global short-range wireless communication technology. Its device types are divided into two categories according to the communication distance: Class1 and Class2, corresponding to the communication distance of 100 meters and 10 meters respectively. Different applications use different types of Bluetooth devices. Bluetooth works in the 2.4GHz frequency band, which is free for industrial, medical and scientific research fields. A Bluetooth master station can maintain an asynchronous connectionless link (Asynchronous Connectionless Link, ACL) between seven active Bluetooth slave stations at the same time, that is, the Bluetooth master station can communicate with seven slave stations at the same time, one master station and multiple slave stations The slave stations form a Bluetooth piconet. For the reliability of ACL link communication, the Bluetooth physical layer adopts frequency hopping strategy, forward error correction, coding optimization and other mechanisms to make the Bluetooth communication link have good anti-interference and high reliability. The above mechanisms ensure that Bluetooth technology can meet the centralized control and reliability requirements of industrial applications. However, the application of Bluetooth in industrial production also needs to solve the following problems: how to design the networking mechanism of Bluetooth devices to ensure the security of Bluetooth communication, and how to improve the robustness and maintainability of the network.

Contents of the invention

The object of the present invention is to provide a bluetooth network networking method and system, aiming at meeting the requirements of safety, robustness and maintainability of industrial production.

According to one aspect of the present invention, an industrial bluetooth network system is provided for communication in industrial places, which includes a bluetooth master station and a plurality of bluetooth slave stations managed by it, and each bluetooth slave station has a corresponding Network key device (NETWORK_KEY, referred to as N_K), wherein,

The network key device is used to realize the interaction of networking filtering parameters between the Bluetooth master station and multiple Bluetooth slave stations managed by it;

Described bluetooth master station, slave station all comprise:

The central control unit (MCU) controls the bluetooth module to perform network management and wireless data transmission and reception through the filtering parameters stored in the network key device; and

The bluetooth module is used to run the bluetooth protocol stack, and accept the control commands of the central control unit and receive the wireless frames sent by other bluetooth master stations or slave stations through the host control interface (Host Controller Interface, HCI);

And, the bluetooth master station also includes:

The network configuration interface circuit is used to set the current piconet ID, the logical address of the slave station and the number of slave stations managed by the master station; and the RS485/CAN bus interface circuit is used for the bluetooth master station and other piconet master stations in the network Formed into a wired network.

As an improvement of the present invention, the N_K is a non-volatile memory, communicates with the Bluetooth master station or slave station through the bus, and stores encrypted network filtering parameters, including the current piconet ID, master station Bluetooth address And the logical address of the slave station.

According to another aspect of the present invention, a method of applying the above-mentioned industrial bluetooth network system for networking is provided, wherein the bluetooth master station performs the following steps:

1) Configure the N_K corresponding to all the Bluetooth slave stations managed by the Bluetooth master station, encrypt and write the Bluetooth address of the master station, the current piconet ID and the logical address of the slave station into the corresponding N_K of each Bluetooth slave station;

2) The central control unit sets the search and filter parameters of the Bluetooth module as the current piconet ID, and orders it to perform a search operation: if the slave device type (CLASS_of_DEVICE) information found by the Bluetooth module does not meet the search filter parameters, the slave will not be The Bluetooth address information of the station is uploaded to the central control unit; after the Bluetooth module searches, if the number of slave station Bluetooth address information obtained by the central control unit is less than the number of slave stations that the Bluetooth master station should manage, the Bluetooth module is ordered to perform the search operation again , otherwise go to step 3);

3) The Bluetooth master station sends ACL link establishment request frames to all the searched slave stations one by one, and waits for all the slave stations to receive the request and establish an ACL link with it, so that the master station and the slave station form a piconet.

As an improvement of the present invention, said step 1) is specifically:

1a) After power on, a BCSP link is established between the central control unit and the Bluetooth module;

1b) The Bluetooth master station detects whether it has inserted N_K, if so, execute step 1c), otherwise execute step 2);

1c) The central control unit reads the bluetooth address of the master station of the bluetooth module through the HCI instruction, and reads the current piconet ID set by the network configuration interface circuit and the logic set for the bluetooth slave station corresponding to the inserted N_K Address, encrypt and store these information to the inserted N_K, and then wait for the user to power off and unplug the inserted N_K. If the corresponding N_K of other Bluetooth slave stations that the Bluetooth master station should manage has not been configured, continue to insert The corresponding N_K of other bluetooth slave stations, and finally return to step 1a).

As an improvement of the present invention, each of the plurality of bluetooth slave stations performs the following steps:

1) Insert the N_K corresponding to the Bluetooth slave station into the slave station, power on and initialize, the central control unit detects whether there is N_K inserted, if not, do not perform any operation, otherwise perform step 2);

2) The central control unit establishes a BCSP link with the Bluetooth module, reads and decrypts the network filtering information in the inserted N_K, and performs parameter configuration on the Bluetooth module through a series of HCI commands, including the device of the slave station The type (CLASS_of_DEVICE) is set to the current piconet ID in the N_K, and the filter parameter of the connection request is set to the Bluetooth address of the master station in the inserted N_K;

3) The Bluetooth slave station enters the waiting state and responds to the search operation and link establishment request of the master station; if a link establishment request frame is received, it judges the source address of the frame and the filtering parameters of the connection request (ie, the master station’s Bluetooth address) are consistent, if they are consistent, establish an ACL link with the master station; otherwise, discard the frame.

As an improvement of the present invention, the current piconet ID stored in the N_K, the logical address of the bluetooth slave station, and the bluetooth address of the master station are encrypted by using a group encryption algorithm; to encrypt.

As an improvement of the present invention, an ACL link guarantee mechanism is set on the Bluetooth master station: the Bluetooth master station monitors the disconnection event with the slave station, starts a device search operation, and when the cause of the disconnection is eliminated, the master station searches for the link again. The slave station performs corresponding reconnection operations to restore its ACL link.

As an improvement of the present invention, the plug-and-play of slave station replacement is realized through the following steps: the N_K on the original slave station is pulled out and inserted into the replaced new slave station, and the parameter configuration is automatically performed after the new slave station is powered on , so that it can be searched by the Bluetooth master station and establish an ACL link with it.

As an improvement of the present invention, under the premise of uninterrupted power supply, the two bluetooth slave stations realize the exchange of piconet affiliation by exchanging corresponding N_K with each other.

As an improvement of the present invention, the specific steps of piconet membership exchange are: when the slave station is powered on, if N_K is replaced, the slave station will compare the information from the new N_K with the original information, and if they are consistent, do not execute Any operation; if inconsistent, the slave station actively disconnects the current link, initializes and sets the device type (CLASS_of_DEVICE) according to the information in the new N_K, and then waits for the link establishment request frame from the master station.

The invention can set up a plurality of co-existing master-slave piconets in the same working area, and each piconet slave station has a clear affiliation relationship, which can prevent unauthorized or illegal bluetooth devices from joining the network; important information in N_K and bluetooth piconets The data transmitted in the network is encrypted to prevent eavesdropping and interpretation of external devices, and meet the security requirements of industrial communications; the established network has a link guarantee mechanism and plug-and-play features, which improve the robustness and maintainability of the network and flexibility.

Description of drawings

Figure 1 shows the hardware structure diagram of the Bluetooth master station.

Figure 2 shows the protocol stack used by the Bluetooth master station and slave station.

Figure 3 shows the main program flow chart of the Bluetooth master station and slave station.

Figure 4 shows the flow chart of the special mechanisms in the Bluetooth master and slave stations.

Figure 5 shows an application scenario where multiple piconets coexist.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

1 Bluetooth device hardware structure and protocol stack adopted

The bluetooth device designed by the present invention includes a bluetooth master station, a bluetooth slave station and N_K, and the hardware structure and functions of these devices are firstly introduced below.

Referring to Figure 1, the dotted line part is a schematic diagram of the hardware structure of the Bluetooth master station, which includes the following parts:

1) The central control unit (MCU), used to control the operation of the Bluetooth module and exchange information with other components of the master station. In this embodiment, the MCU may be a single chip microcomputer.

2) The Bluetooth module is used to run the Bluetooth protocol stack, exchange information with the Bluetooth modules of other sites and the MCU of this site, and provide the host control interface (Host Controller Interface, HCI) for the MCU of the main site.

3) The network configuration interface circuit is used to set the current piconet ID, the logical address of the slave station and the number of slave stations managed by the master station. In this embodiment, the configuration interface circuit may be a dial switch.

4) The RS485/CAN bus interface circuit is used to form a wired network with other piconet master stations to realize the integration of wired communication and wireless communication.

5) The power management module is used to supply power to the Bluetooth module, MCU and other components.

The difference between the Bluetooth slave station and the master station is that the slave station has no network configuration interface circuit and RS485/CAN bus interface circuit. That is, the Bluetooth slave station also includes:

Central Control Unit (MCU), used to control the operation of the Bluetooth module, and to interact with other components of the slave station; and

The Bluetooth module is used to run the Bluetooth protocol stack, exchange information with the Bluetooth modules of other sites and the central control unit of this site, and provide the host control interface (Host Controller Interface, HCI) for the central control unit.

As for the network key device (NETWORK_KEY), its storage chip is a non-volatile memory, such as FLASH or EEPROM that can save data when power is turned off. The network key device is connected with the MCU of the bluetooth device through the I2C bus. The N_K is used to realize the interaction of networking filtering parameters between the Bluetooth master station and multiple Bluetooth slave stations managed by it.

FIG. 2 is a schematic diagram of a protocol stack adopted by a Bluetooth device. In this figure, the Bluetooth host refers to the MCU, and the Bluetooth controller refers to the Bluetooth module. The two interact through the HCI interface. The so-called HCI refers to a unified instruction method provided by Bluetooth to access its hardware. Through this instruction, The user can control the operation of the local Bluetooth hardware and control its link layer connections with other Bluetooth devices. In the present invention, the Bluetooth host implements special network networking and data transmission functions through a series of HCI commands.

In Figure 2, the MCU and the Bluetooth module are connected through the UART line, and the data frames transmitted on the UART line are in the BCSP format (BlueCore Serial Protocol, an available protocol for transmitting HCI data packets between the Bluetooth device and the system). The control frames and data frames communicated between the MCU and the Bluetooth module are packaged in BCSP format. After the Bluetooth network is established, the MCU and the Bluetooth module package data frames in the format of L2CAP (Logical Link Control and Adaptation Protocol, which is the core protocol in the Bluetooth system and is responsible for adapting the upper layer protocol in the baseband), and then send the data through the Bluetooth module. The data received from the Bluetooth module is uploaded to the MCU.

2 Bluetooth networking process introduction

All the programs designed by the present invention run on the MCU, and operate the bluetooth module through the HCI interface. The flow chart of the program in the Bluetooth master-slave station is shown in Figure 3.

In the scenario described in Figure 5, there are two Bluetooth master stations (BS1, BS2), six Bluetooth slave stations (C1_1, C1_2, C1_3, C2_1, C2_2, C2_3), each Bluetooth slave station has a corresponding N_K. Utilizing the networking method proposed by the invention, these bluetooth devices can form two secure piconets that do not interfere with each other. Taking piconet N1 as an example, the specific networking steps are as follows:

The execution steps of BS1 are as follows:

1) Set up the network configuration interface circuit (dip switch) on BS1 according to the requirements, and then power it on. At this time, a BCSP link is established between the MCU and the Bluetooth module according to a certain mechanism, and then perform the second step.

2) BS1 detects whether it has inserted N_K, if so, execute the third step, otherwise execute the fourth step.

3) The MCU performs the following operations: read the local address of the Bluetooth module through the HCI command; read the logical address of the slave station C1_1 set by the DIP switch; read the current piconet ID set by the DIP switch; store these information encrypted in N_K11 corresponding to the slave station C1_1; the program performs an empty cycle, waiting for the user to power off the operation.

Use the same steps to store the information to N_K12 and N_K13, where the logical address of the slave station is different, and other information is the same.

4) BS1 initializes the Bluetooth module through the MCU, uses the piconet ID as a search filter parameter of the Bluetooth module, and commands it to perform a search operation. If the slave station device type (CLASS_of_DEVICE) information searched by the Bluetooth module does not meet the search filter parameters, the Bluetooth address information of the slave station will not be uploaded to the MCU; after the Bluetooth module searches, if the number of address information obtained by the MCU is less than that of the master If the number of slave stations that the station should manage, the MCU commands the Bluetooth module to perform the search operation again, otherwise, perform the fifth step.

5) BS1 sends an ACL link establishment request frame to all the slave stations found one by one, and waits for all the slave stations to receive the request and establish a link with it, so that the master station and the slave stations form a piconet, at this time Data exchange can be carried out between the Bluetooth master station and the slave station.

The execution steps of Bluetooth slave station C1_1 are as follows (C1_2 and C1_3 adopt the same steps):

1) Insert the N_K11 storing information into C1_1, and then power on. At this time, a BCSP link is established between the MCU and the Bluetooth module, and then C1_1 starts the initialization operation, that is, executes the second step. If it detects that N_K11 is not connected when it is powered on, it will not perform any operation.

2) The initialization operation refers to: the MCU operates the Bluetooth module through a series of HCI instructions, including setting the CLASS_of_DEVICE of the slave station to the piconet ID in N_K11, and setting the filter parameters of the connection request to the Bluetooth address of the master station.

3) After the initialization is completed, C1_1 is in a waiting state, responding to the search operation and link establishment request of the master station. If a link establishment request frame is received, it is judged whether the source address of the frame is consistent with the filtering parameters of its own connection request (ie BS1 Bluetooth address), and if they are consistent, an ACL link is established with the master station; otherwise, the frame is discarded.

Through the above steps, BS1 only forms a Bluetooth piconet with C1_1, C1_2, and C1_3 that meet the requirements, preventing other Bluetooth nodes from joining in the same scene, and realizing the exclusiveness of Bluetooth networking.

3 Network Security Mechanisms

Through the above operations, an ACL link is respectively established between the Bluetooth master station and all its subordinate slave stations, thereby forming a Bluetooth piconet. The present invention also designs two mechanisms to ensure the security of the network and meet the requirements of industrial wireless communication. The two mechanisms are as follows:

3.1 Exclusivity of Network Formation

Due to the existence of the frequency hopping mechanism, only the slave station that has established a link can synchronize with the clock of the master station and obtain the frequency hopping sequence list of the master station, thereby realizing data exchange with the master station. Devices that are not part of the network cannot monitor or interfere with network communications because they do not know the communication channels used by the network at any time. Therefore, the exclusive networking method proposed by the present invention can improve the security of the piconet.

The so-called exclusivity of Bluetooth networking means that only Bluetooth master stations and slave stations that meet specific requirements can form a piconet. Referring to Figure 5, it is assumed that the following functions need to be realized: there are two piconets in the same site, the piconet N1 is composed of the master station BS1 and the slave stations C1_1, C1_2, C1_3, the piconet N2 is composed of the master station BS2 and the slave station C2_1, C2_2, C2_3 composition. Each of these Bluetooth slaves has its own corresponding N_K at runtime.

According to the steps described in Figure 3, before the Bluetooth master station and the slave station are both powered on to form a piconet, it has the following characteristics:

1) The query filter parameters of the Bluetooth master station are consistent with the CLASS_of_DEVICE of the Bluetooth slave station itself, and its value is set by the dial switch on the master station and written into the piconet ID value in N_K.

2) The connection filter parameters of the Bluetooth slave station are consistent with the Bluetooth address of the Bluetooth master station itself, and its value is also written into N_K.

According to the above characteristics, the following analyzes how to realize the exclusivity of network networking:

1) The Bluetooth master station selects the slave station: the query filter parameter value of the Bluetooth master station is completely consistent with the CLASS_of_DEVICE of the Bluetooth slave station. In Figure 5, although both C1_1 and C2_3 are within the communication range of BS1, only the CLASS_of_DEVICE of C1_1 meets the filtering conditions of BS1's query. Therefore, BS1 will only obtain the address of C1_1 during the query process, and BS1 will only obtain the address of C1_1 when building a network. Send a link establishment request frame to C1_1. Therefore, the master station selects the slave station.

2) The Bluetooth slave station selects the master station. During the networking process, the connection filter parameters of the Bluetooth slave station are exactly the same as the Bluetooth address of the master station. Taking FIG. 5 as an example, assume that C1_1 receives the link establishment request frame of BS1 and simultaneously receives the link establishment request frame of BS2 due to an unexpected situation. C1_1 will judge whether the source address of the request frame is consistent with its connection filtering parameter, because the connection filtering parameter of C1_1 is the Bluetooth address of BS1. C1_1 will discard the link request frame sent by BS2 and receive the link request frame from BS1. Therefore, the function of selecting the master station from the station is realized.

From the above analysis, it can be seen that the operator can realize the exclusivity of the network through N_K and setting the DIP switch of the master station, so that the Bluetooth devices that have not been authorized and certified cannot join the Bluetooth network, so as to improve the security of the network. safety.

3.2 Encryption mechanism

The security of the Bluetooth network is improved through networking exclusivity, but there are still two potential security risks in the network: First, the important information stored in N_K has not been processed. The information in the network may analyze the networking mechanism and parameters of the piconet; secondly, the data transmitted on the ACL link is not encrypted, and these data may still be stolen by external devices. To this end, the present invention proposes a corresponding solution.

1) The information stored in N_K is the current piconet ID, the logical address of the slave node and the Bluetooth address of the Bluetooth master. The final data is stored in N_K, and the slave station reads and decrypts the parameters in N_K, and then uses these parameters in the network construction operation. In the present invention, the N_K information length is 11 bytes, which is expanded to 16 bytes, and can be encrypted into a new 16-byte ciphertext by using the DES algorithm. Encrypting and decrypting N_K requires the Bluetooth master and slave to use the same key.

2) For the data transmitted on the ACL link, since the length of these data is not fixed, it cannot be encrypted by the block algorithm, so the sequence cipher algorithm (also known as the stream cipher algorithm) is used to encrypt the transmitted data stream . The present invention adopts the byte-oriented RC4 algorithm, which is widely used in the field of wireless communication due to its simple structure and high processing efficiency. The master and slave stations only need to use the same key to realize the encryption and decryption of data.

In the present invention, through the three-layer security strategy of encrypting N_K storage information before networking, using N_K information in networking for exclusive networking, and encrypting data transmitted in the network after networking, unauthorized access can be prevented. And illegal equipment steals the information of Bluetooth piconet and the data transmitted, which greatly improves the security of the network.

Due to the existence of the frequency hopping mechanism, the data communication between adjacent piconets does not interfere with each other. In addition, the exclusive networking mechanism and corresponding encryption mechanism designed by the present invention realize the establishment of multiple coexisting networks in the same scene. Secure piconet functionality.

4 Network maintainability and flexibility analysis

After improving the security of piconet communication, it is necessary to further improve the robustness and maintainability of the system. Specifically, it refers to the automatic reconnection of broken links without affecting the communication of other intact links, and the ease of replacement of faulty slaves. Station and under the premise of uninterrupted power supply, the change of the bluetooth slave station belonging to the piconet is realized through the hot plugging of N_K. The implementation of the above mechanism is explained below in conjunction with FIG. 5 .

1) The Bluetooth master station is designed with an ACL link guarantee mechanism. For example, if the ACL link between BS1 and C1_1 is disconnected due to instantaneous electromagnetic interference or power failure of the slave station, the master station can monitor this link disconnection event, And start the device search operation. When the interference disappears or the slave station is powered on again, the master station can search for the slave station again and perform the corresponding reconnection operation to restore the ACL link between BS1 and C1_1. When the master station performs scanning and connection operations, it will not affect the ACL link communication between it and C1_2 and C1_3. The specific guarantee mechanism flow chart is shown in Figure 4(a). This link guarantee mechanism improves the robustness of the Bluetooth piconet, and enhances the system's anti-interference ability and fault recovery ability.

2) The above link guarantee mechanism can improve the maintainability of the network. For example, C1_1 in Figure 5 has a permanent fault and needs to be replaced with a new slave station. When BS1 detects that the ACL link is disconnected, it starts the search operation and Remind the operator to perform network maintenance through the corresponding status indication. At this time, the operator only needs to pull out the N_K on the faulty slave station and insert it into the replaced new slave station. After the new slave station is powered on, the parameter configuration can be performed automatically. So that it can be scanned by BS1 and establish an ACL link with it, so as to realize the plug-and-play of slave station replacement.

3) A mechanism to improve the flexibility of networking is designed at the slave station: as shown in Figure 5, if C1_3 and C2_1 are within the effective communication range of BS1 and BS2 at the same time, the two slave stations can The exchange of piconet affiliation is realized by exchanging each other's N_K. The flow chart of this mechanism is shown in Figure 4(b), and the specific process is as follows: When the slave station is running with electricity, if N_K is replaced, the MCU will generate an interrupt signal at the moment of inserting N_K, and in the interrupt service routine, the slave station will come from the new The information in the N_K is compared with the original information. If it is consistent, no operation is performed; if it is inconsistent, the slave station actively disconnects the current link, and initializes and sets CLASS_of_DEVICE according to the information in the new N_K, and then Wait for a link establishment request frame from the master station. After the current master station receives the link disconnection information, it executes the operation in the link guarantee mechanism to restore the link. Through the above operation process, C1_3 and C2_1 realize the exchange of the piconets they belong to. These operations do not affect N1 and C2_1. The communication of other normal links in N2 improves the flexibility of networking.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (8)

1. An industrial bluetooth network system used for network communication in industrial places, which includes a bluetooth master station and a plurality of bluetooth slave stations managed by it, and each bluetooth slave station has a corresponding network key device ( NETWORK_KEY), where, The network key device is a non-volatile memory, which communicates with the Bluetooth master station or slave station through a bus, and stores encrypted network filtering parameters, including the current piconet ID, master station Bluetooth address and slave station Logical address, the network key device is used to realize the interaction of networking filtering parameters between the Bluetooth master station and multiple Bluetooth slave stations managed by it; Described bluetooth master station, slave station all comprise: The central control unit (MCU) controls the bluetooth module to perform network management and wireless data transmission and reception through the network filtering parameters stored in the network key device, including: the central control unit on the bluetooth master station sets the search filtering parameters to the current pico Network ID, order it to perform search operations and send ACL link establishment request frames to all searched slave stations one by one; the central control unit on the Bluetooth slave station establishes a BCSP link with the Bluetooth module, reads and decrypts the inserted network key The networking in the device filters information, and performs parameter configuration on the Bluetooth module through a series of HCI instructions, including setting the device type of the slave station as the current piconet ID in the network key device, and filtering the connection request The parameter is set to the Bluetooth address of the master station in the inserted network key device; and The bluetooth module is used to run the bluetooth protocol stack, and accepts the control commands of the central control unit and the wireless frames sent by other master stations or slave stations through the host control interface (Host Controller Interface, HCI); And, the bluetooth master station also includes: The network configuration interface circuit is used to set the current piconet ID, the logical address of the slave station and the number of slave stations managed by the master station; and The RS485/CAN bus interface circuit is used for the bluetooth master station to form a wired network with other piconet master stations in the network. 2. A networking method applied to the industrial bluetooth network system according to claim 1, wherein the bluetooth master station performs the following steps: 1) Configure the network key device corresponding to all the Bluetooth slave stations managed by the Bluetooth master station, encrypt and write the Bluetooth address of the master station, the current piconet ID and the logical address of the slave station into the network key device corresponding to each Bluetooth slave station ; 2) The central control unit sets the search and filter parameters of the Bluetooth module as the current piconet ID, and orders it to perform a search operation: if the slave station device type (CLASS_of_DEVICE) information searched by the Bluetooth module does not meet the search filter parameters, the slave will not be The Bluetooth address information of the station is uploaded to the central control unit; after the Bluetooth module searches, if the number of slave station Bluetooth address information obtained by the central control unit is less than the number of slave stations that the Bluetooth master station should manage, the Bluetooth module is ordered to perform the search operation again , otherwise execute step 3); 3) The Bluetooth master station sends an ACL link establishment request frame to all the slave stations searched one by one, waiting for all the slave stations to receive the request and establish an ACL link with it, thus the master station and the slave station form a piconet; Wherein, each of the plurality of bluetooth slave stations performs the following steps: A) Insert the network key device corresponding to the Bluetooth slave station into the slave station, power on and initialize, the central control unit detects whether there is a network key device inserted, if not, then do not perform any operation, otherwise perform step B) ; B) The central control unit establishes a BCSP link with the Bluetooth module, reads and decrypts the network filtering information in the inserted network key device, and performs parameter configuration on the Bluetooth module through a series of HCI instructions, including the slave The device type (CLASS_of_DEVICE) of the station is set to the current piconet ID in the network key device, and the filter parameter of the connection request is set to the master station bluetooth address in the inserted network key device; C) the bluetooth slave station enters a waiting state, and responds to a search operation and a link establishment request of the master station; if a link establishment request frame is received, it is judged whether the source address of the frame is consistent with the filter parameters of the connection request, If they are consistent, establish an ACL link with the master station; otherwise, discard the frame. 3. The networking method according to claim 2, wherein the step 1) is specifically: 1a) After power-on, a BCSP link is established between the central control unit and the Bluetooth module; 1b) The bluetooth master station detects whether it has inserted a network key device, if so, executes step 1c), otherwise executes step 2); 1c) The central control unit reads the bluetooth address of the master station of the bluetooth module through the HCI instruction, and reads the current piconet ID set by the network configuration interface circuit and the bluetooth slave station corresponding to the inserted network key device Set the logical address, encrypt and store these information to the inserted network key device, and then wait for the user to power off and unplug the inserted network key device, if the other Bluetooth slave stations that the Bluetooth master station should manage correspond to If the configuration of the network key device has not been completed, continue to insert the corresponding network key devices of other Bluetooth slave stations, and finally return to step 1a). 4. The networking method according to claim 2 or 3, wherein, the current piconet ID stored in the network key device, the logical address of the bluetooth slave station and the bluetooth address of the master station are encrypted by using a packet encryption algorithm; A sequence cipher algorithm is used to encrypt the transmission data on the ACL link. 5. The networking method according to claim 2 or 3, wherein, an ACL link guarantee mechanism is set on the bluetooth master station: the bluetooth master station monitors the disconnection event with the slave station, starts a device search operation, and when the disconnection When the cause of the link is eliminated, the master station searches for the slave station again and performs the corresponding reconnection operation to restore the ACL link with it. 6. The networking method according to claim 2 or 3, wherein the plug-and-play of slave station replacement is realized through the following steps: pull out the network key device on the original slave station and insert it into the new slave station after replacement station, after the new slave station is powered on, it automatically executes the parameter configuration, so that it can be searched by the Bluetooth master station and establish an ACL link with it. 7. The networking method according to claim 2 or 3, wherein, under the premise of uninterrupted power supply, the two bluetooth slave stations realize the exchange of piconet affiliation by exchanging corresponding network key devices. 8. The networking method according to claim 7, wherein the specific steps of piconet affiliation exchange are: When the slave station is running with electricity, if the network key device is replaced, the slave station will compare the information from the new network key device with the original information, and if they are consistent, no operation will be performed; Actively disconnect the current link, initialize and set the device type (CLASS_of_DEVICE) according to the information in the new network key device, and then the master station re-establishes a link with the slave station according to the ACL link guarantee mechanism.