Method for transmitting Profinet RT protocol message through wireless link

Abstract

The invention relates to the technical field of wireless communication, and provides a method for transmitting a Profinet RT protocol message through a wireless link, which comprises the following steps of: establishing a wireless virtual interface and an 802.1 q sub-interface which support four-address 802.11 message analysis, and adding the wireless virtual interface and the 802.1 q sub-interface into a network bridge; configuring a wireless virtual interface to reserve a VLAN label and priority information; setting a QoS (Quality of Service) strategy and a WMM (Wireless Message Management) mechanism to map the message containing the VLAN priority to a high-priority queue and a voice access category; and bidirectional encapsulation and de-encapsulation transmission of an 802.3 real-time message and a four-address 802.11 frame is realized. According to the invention, transparent transmission of the Profinet RT protocol on a wireless link is realized, and the real-time performance and reliability of industrial automatic wireless communication are improved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a method and system for transmitting Profinet RT protocol messages via a wireless link. Background Technology

[0002] Profinet RT (Real-Time Ethernet) is a standard industrial Ethernet protocol commonly used in industrial automation control systems. It is widely used for high-speed real-time data exchange between field devices such as controllers, input / output devices, drives, and sensors. The Profinet RT protocol bypasses the processing latency of the TCP / IP protocol stack, uses an independent real-time channel, and employs priority tags to ensure real-time message transmission. Jitter must be controlled at the microsecond level to meet the precise industrial control requirements. Traditional Profinet RT communication heavily relies on the physical characteristics of wired Ethernet. In scenarios such as mobile device integration and simplified wiring for rotating equipment, wired connections have inherent drawbacks such as high wiring costs, poor flexibility, difficult maintenance, and restrictions on equipment movement.

[0003] In existing technologies, attempts to migrate Profinet RT to wireless links primarily employ traditional Layer 3 routing models for wireless transmission. However, existing methods do not adequately consider the inherent relationship between the Layer 2 transparent transmission characteristics of the Profinet RT protocol and the media access control mechanism of wireless networks, making it difficult to organically integrate the random latency jitter characteristics of wireless transmission with the deterministic latency requirements of real-time industrial control. In traditional wireless modes, APs and STAs rewrite the source and destination MAC addresses of data frames when transmitting data packets. This is fatal for Profinet RT packets that require transparent transmission of Layer 2 MAC addresses, leading to communication interruptions and hindering the achievement of highly reliable, high-real-time industrial-grade wireless Profinet RT communication. Summary of the Invention

[0004] In view of this, the present invention proposes a method for transmitting Profinet RT protocol messages via a wireless link, which solves the problem that in the traditional wireless mode, the AP and STA rewrite the source MAC address and destination MAC address of the data frame when transmitting data messages, which will cause communication interruption and make it impossible to achieve high reliability and high real-time industrial-grade wireless Profinet RT communication.

[0005] The technical solution of this invention is implemented as follows: This invention provides a method for transmitting ProfinetRT protocol messages via a wireless link, comprising the following steps: Establish wireless virtual interfaces that support four-address 802.11 packet parsing at wireless access points and wireless sites; Establish an 802.1q sub-interface, and add the 802.1q sub-interface and the wireless virtual interface to the bridge; Configure the wireless virtual interface to retain the VLAN tag and VLAN priority; Configure quality of service policies and wireless multimedia mechanisms to map packets, including those with virtual LAN priority, to high-priority queues and voice access categories; Receive 802.3 real-time packets including the virtual LAN priority, encapsulate the 802.3 real-time packets into four-address 802.11 frames and send them; The four-address 802.11 frames are received, decapsulated, and 802.3 real-time packets are obtained and forwarded.

[0006] Based on the above technical solutions, preferably, the establishment of a wireless virtual interface supporting four-address 802.11 packet parsing at the wireless access point and wireless station includes: The four addresses include the media access control address of the receiving wireless station, the media access control address of the sending wireless access point, the destination media access control address of the original message, and the source media access control address of the original message. The Layer 2 media access control address information of the original message is completely preserved and transmitted through the four addresses.

[0007] Based on the above technical solutions, preferably, the wireless virtual interface adopts WDS bridging mode and transmits four-address 802.11 messages through WDS frame format, wherein the first address is the media access control address of the receiving wireless station, the second address is the media access control address of the sending wireless access point, the third address is the destination media access control address of the original message, and the fourth address is the source media access control address of the original message.

[0008] Based on the above technical solutions, preferably, the configuration of the wireless virtual interface to retain the virtual LAN label and virtual LAN priority includes: The driver of the wireless virtual interface is modified so that it retains the VLAN tag and VLAN priority in the Media Access Control header when converting 802.3 and 802.11 packets, and the switching chip connected to the wired port is configured to transparently transmit Layer 2 priority frames.

[0009] Based on the above technical solutions, preferably, the modification of the driver for the wireless virtual interface includes: Add support for 802.1Q packet forwarding so that the wireless virtual interface can fully retain the VLAN priority information contained in the 802.1Q packet with the identifier 0 during the process of encapsulating 802.3 packets into 802.11 packets and decapsulating 802.11 packets into 802.3 packets.

[0010] Based on the above technical solutions, preferably, the configuration of the Quality of Service (QoS) policy and wireless multimedia mechanism maps packets including the virtual local area network (VLAN) priority to high-priority queues and voice access categories, including: Configure a quality of service policy on the wired side to map packets with VLAN priority 5 and 6 to the highest priority queue. Enable the wireless multimedia mechanism on the wireless side to map packets with VLAN priority 5 and 6 to the voice access category.

[0011] Based on the above technical solutions, preferably, the voice access category is configured with the shortest arbitration inter-frame interval and the smallest contention window, and the packets of virtual LAN priorities 5 and 6 have the highest access priority and the smallest media access delay in wireless channel contention.

[0012] Based on the above technical solutions, preferably, the step of establishing an 802.1q sub-interface and adding the 802.1q sub-interface and the wireless virtual interface to the bridge includes: Establish an 802.1q sub-interface for identifying and forwarding Layer 2 priority frames; The 802.1q sub-interface and the wireless virtual interface are added to the bridge so that wired and wireless packets are forwarded locally on the device.

[0013] Based on the above technical solutions, preferably, the step of receiving 802.3 real-time packets including the virtual LAN priority, encapsulating the 802.3 real-time packets into four-address 802.11 frames and sending them includes: The 802.3 real-time packets are scheduled to the voice access category queue according to the virtual LAN priority. The original Layer 2 Media Access Control address information of the 802.3 real-time message is encapsulated into the address field of a four-address 802.11 frame and transmitted via a wireless channel.

[0014] Based on the above technical solutions, preferably, the step of receiving the four-address 802.11 frame, decapsulating the four-address 802.11 frame to obtain an 802.3 real-time packet and forwarding it includes: Extract the original Layer 2 Media Access Control address information from the address field of the four-address 802.11 frames; The original Layer 2 Media Access Control address information is used to reconstruct 802.3 real-time packets and forward them through a high-priority wired queue.

[0015] The method and system for transmitting Profinet RT protocol messages via a wireless link according to the present invention have the following advantages over the prior art: (1) By establishing a wireless virtual interface that supports four-address 802.11 packet parsing and configuring virtual LAN tag retention, high-priority packets are mapped to the voice access category queue using the quality of service policy and wireless multimedia mechanism. Combined with the bridge transparent forwarding mechanism, bidirectional encapsulation and conversion of 802.3 real-time packets and four-address 802.11 frames are realized, and the transparent transmission of the Profinet RT protocol on the wireless link is achieved, which improves the real-time performance and reliability of industrial automation wireless communication. At the same time, the priority queue scheduling mechanism ensures the microsecond-level real-time control requirements. (2) By adopting WDS bridging mode to establish a wireless virtual interface and defining a four-address 802.11 message format, the first and second addresses are used to identify the MAC address of the transceiver wireless device, and the third and fourth addresses are combined to completely preserve the destination MAC address and source MAC address of the original message. The orderly encapsulation and transmission of the four-address information are realized through the WDS frame format, thus realizing the Layer 2 transparent bridging transmission of Profinet RT protocol messages on the wireless link. (3) By modifying the driver of the wireless virtual interface and adding support for 802.1Q message forwarding, the modified driver fully preserves the virtual LAN tag and priority information during the bidirectional conversion of 802.3 and 802.11 messages. Combined with the transparent transmission configuration of the switching chip, the end-to-end transmission of the Layer 2 priority frame is realized. By specially processing the 802.1Q message with the identifier 0, the key virtual LAN priority data is preserved, thus realizing the transparent transmission of the Profinet RT protocol and improving the service quality assurance capability of industrial real-time communication. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of a method for transmitting Profinet RT protocol messages via a wireless link according to the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1 This invention provides a method for transmitting Profinet RT protocol messages via a wireless link, comprising the following steps: Establish wireless virtual interfaces that support four-address 802.11 packet parsing at wireless access points and wireless sites; Establish an 802.1q sub-interface, and add the 802.1q sub-interface and the wireless virtual interface to the bridge; Configure the wireless virtual interface to retain the VLAN tag and VLAN priority; Configure quality of service policies and wireless multimedia mechanisms to map packets, including those with virtual LAN priority, to high-priority queues and voice access categories; Receive 802.3 real-time packets including the virtual LAN priority, encapsulate the 802.3 real-time packets into four-address 802.11 frames and send them; The four-address 802.11 frames are received, decapsulated, and 802.3 real-time packets are obtained and forwarded.

[0020] Specifically, this embodiment establishes a wireless virtual interface supporting four-address 802.11 packet parsing and configures virtual LAN tag retention. It utilizes Quality of Service (QoS) policies and wireless multimedia mechanisms to map high-priority packets to voice access category queues. Combined with a bridge transparent forwarding mechanism, it achieves bidirectional encapsulation and conversion between 802.3 real-time packets and four-address 802.11 frames. This embodiment solves the communication interruption problem caused by MAC address rewriting in traditional wireless transmission by completely preserving the original Layer 2 MAC address information, realizing transparent transmission of the Profinet RT protocol on the wireless link, improving the real-time performance and reliability of industrial automation wireless communication, and ensuring microsecond-level real-time control requirements through a priority queue scheduling mechanism.

[0021] The establishment of a wireless virtual interface supporting four-address 802.11 packet parsing at the wireless access point and wireless station includes: The four addresses include the media access control address of the receiving wireless station, the media access control address of the sending wireless access point, the destination media access control address of the original message, and the source media access control address of the original message. The Layer 2 media access control address information of the original message is completely preserved and transmitted through the four addresses.

[0022] The wireless virtual interface adopts WDS bridging mode and transmits four-address 802.11 messages in WDS frame format. The first address is the media access control address of the receiving wireless station, the second address is the media access control address of the sending wireless access point, the third address is the destination media access control address of the original message, and the fourth address is the source media access control address of the original message.

[0023] Specifically, this embodiment establishes a wireless virtual interface using WDS bridging mode and defines a four-address 802.11 message format. The first and second addresses are used to identify the MAC addresses of the transceiver wireless devices. The third and fourth addresses are combined to completely preserve the destination and source MAC addresses of the original message. The WDS frame format is used to achieve ordered encapsulation and transmission of the four-address information. This embodiment solves the problem of Layer 2 transparency loss caused by AP and STA rewriting data frame MAC addresses in traditional wireless transmission, and achieves transparent Layer 2 bridging transmission of Profinet RT protocol messages on the wireless link.

[0024] The step of establishing an 802.1q sub-interface and adding the 802.1q sub-interface and the wireless virtual interface to the bridge includes: Establish an 802.1q sub-interface for identifying and forwarding Layer 2 priority frames.

[0025] In one specific embodiment, the 802.1q sub-interface is a virtual sub-interface established on the wired interface. It identifies and forwards Layer 2 priority frames through 802.1Q packets with a video identifier equal to 0. The Layer 2 priority frames include device configuration protocol packets and periodic input / output data packets in Profinet RT packets.

[0026] The 802.1q sub-interface and the wireless virtual interface are added to the bridge so that wired and wireless packets are forwarded locally on the device.

[0027] In one specific embodiment, adding the 802.1q sub-interface and the wireless virtual interface to the bridge includes adding the 802.1q sub-interface of the wired interface and the wireless virtual interface to the same bridge group respectively, and establishing a Layer 2 forwarding path between the wired port and the wireless port through the bridge forwarding table.

[0028] Specifically, this embodiment establishes an 802.1q sub-interface that identifies 802.1Q packets with a video identifier equal to 0 and adds it to the same bridge group as the wireless virtual interface. It then uses the bridge forwarding table to establish a Layer 2 forwarding path between the wired and wireless ports. Combined with the virtual sub-interface's specialized identification and processing of DCP packets and periodic IO data packets in the Profinet RT protocol, transparent Layer 2 bridging between the wired Ethernet interface and the wireless interface is achieved. This embodiment solves the packet forwarding problem in wired-wireless hybrid networking in industrial real-time communication, ensuring seamless switching and transmission of Profinet RT device configuration protocols and real-time data between wired and wireless links, and improving the flexibility and scalability of industrial automation networks.

[0029] The configuration of the wireless virtual interface to retain the VLAN tag and VLAN priority includes: The driver of the wireless virtual interface is modified so that it retains the VLAN tag and VLAN priority in the Media Access Control header when converting 802.3 and 802.11 packets, and the switching chip connected to the wired port is configured to transparently transmit Layer 2 priority frames.

[0030] The driver modification for the wireless virtual interface includes: Add support for 802.1Q packet forwarding so that the wireless virtual interface can fully retain the VLAN priority information contained in the 802.1Q packet with the identifier 0 during the process of encapsulating 802.3 packets into 802.11 packets and decapsulating 802.11 packets into 802.3 packets.

[0031] Specifically, this embodiment modifies the driver for the wireless virtual interface and adds support for 802.1Q packet forwarding. The modified driver fully preserves the VLAN tag and priority information during bidirectional conversion between 802.3 and 802.11 packets. Combined with the transparent transmission configuration of the switching chip, it achieves end-to-end transmission of Layer 2 priority frames. Furthermore, it preserves critical VLAN priority data by specifically processing 802.1Q packets with a flag of 0. This embodiment solves the problem of traditional wireless devices losing industrial Ethernet priority identifiers during packet format conversion, achieves transparent transmission of the ProfinetRT protocol, and improves the quality of service (QoS) assurance capabilities of industrial real-time communication.

[0032] The configured Quality of Service (QoS) policy and wireless multimedia mechanism map packets, including those with virtual LAN priority, to high-priority queues and voice access categories, including: Configure a quality of service policy on the wired side to map packets with VLAN priority 5 and 6 to the highest priority queue. Enable the wireless multimedia mechanism on the wireless side to map packets with VLAN priority 5 and 6 to the voice access category.

[0033] The voice access category is configured with the shortest arbitration inter-frame interval and the smallest contention window, and the packets of the virtual LAN priorities 5 and 6 have the highest access priority and the smallest media access delay in wireless channel contention.

[0034] Specifically, this embodiment maps VLAN priority 5 and 6 packets to the highest priority queue by configuring a Quality of Service (QoS) policy on the wired side, and maps packets of the same priority to the voice access category using the wireless multimedia mechanism on the wireless side. It also utilizes the shortest arbitration inter-frame interval and minimum contention window configuration of the voice access category to achieve end-to-end priority guarantee and minimum media access latency for high-priority Profinet RT packets on wired and wireless links. This embodiment solves the problems of random latency jitter and channel contention faced by industrial real-time communication in wireless environments, ensuring that critical industrial control messages obtain the highest access priority in wireless transmission, and improving the real-time transmission performance and deterministic latency guarantee capability of the Profinet RT protocol on wireless links.

[0035] The receiving of 802.3 real-time packets including the virtual LAN priority, encapsulating the 802.3 real-time packets into four-address 802.11 frames and sending them includes: The 802.3 real-time packets are scheduled to the voice access category queue according to the virtual LAN priority.

[0036] In one specific embodiment, scheduling the 802.3 real-time packets to the voice access category queue according to the virtual LAN priority includes scheduling packets with virtual LAN priorities of 5 and 6 to the voice access category queue, so that the 802.3 real-time packets have the highest access priority in wireless channel contention.

[0037] The original Layer 2 Media Access Control address information of the 802.3 real-time message is encapsulated into the address field of a four-address 802.11 frame and transmitted via a wireless channel.

[0038] In one specific embodiment, encapsulating the original Layer 2 Media Access Control address information of the 802.3 real-time message into the address field of a four-address 802.11 frame includes: The source media access control address and destination media access control address of the original message are encapsulated into the fourth address field and the third address field of the four-address 802.11 frame, respectively.

[0039] Specifically, this embodiment intelligently schedules 802.3 real-time packets to the voice access category queue based on VLAN priority. It utilizes the highest access priority of VLAN priority 5 and 6 packets in wireless channel contention, and combines this with the four-address 802.11 frame format to encapsulate the source and destination media access control addresses of the original packets into the fourth and third address fields, respectively. This embodiment solves the dual technical challenges of priority scheduling and address information preservation faced by industrial real-time packets during wireless transmission. It achieves high-priority wireless transmission of Profinet RT protocol packets and complete encapsulation and forwarding of original Layer 2 address information, improving the real-time performance and protocol transparency of industrial automation wireless communication.

[0040] The process of receiving the four-address 802.11 frame, decapsulating the four-address 802.11 frame to obtain an 802.3 real-time packet, and forwarding it includes: Extract the original Layer 2 Media Access Control address information from the address field of the four-address 802.11 frame.

[0041] In one specific embodiment, extracting the original Layer 2 Media Access Control address information from the address field of a four-address 802.11 frame includes: Extract the destination media access control address of the original message from the third address field, and extract the source media access control address of the original message from the fourth address field.

[0042] The original Layer 2 Media Access Control address information is used to reconstruct 802.3 real-time packets and forward them through a high-priority wired queue.

[0043] In one specific embodiment, the step of reconstructing the 802.3 real-time packet using the original Layer 2 Media Access Control address information and forwarding it through a high-priority wired queue includes: The extracted original Layer 2 Media Access Control (MAC) address information is re-encapsulated into 802.3 real-time packets including VLAN priority, and the 802.3 real-time packets are mapped to high-priority queues on the wired side for forwarding according to the VLAN priority.

[0044] Specifically, this embodiment accurately extracts the destination Media Access Control (MAC) address and source MAC address of the original packet from the third and fourth address fields of the four-address 802.11 frame. Using the extracted original Layer 2 address information, it reconstructs the 802.3 real-time packet containing VLAN priority. Combined with a wired-side high-priority queue mapping mechanism based on VLAN priority, this solves the problem of reverse conversion and address information recovery from four-address 802.11 frames at the wireless receiver to standard 802.3 Ethernet packets. This embodiment achieves transparent and lossless forwarding of Profinet RT protocol packets from the wireless link to the wired Ethernet, improving protocol compatibility and real-time performance in wireless-to-wired transmission in industrial automation hybrid networks, and ensuring the integrity and priority consistency of critical industrial control data during network boundary transitions.

[0045] In one specific embodiment, a specific implementation scheme for transmitting Profinet RT protocol messages via a wireless link is provided. This scheme uses WDS bridging technology to establish a Layer 2 transparent transmission channel.

[0046] In this embodiment, the system includes a wireless access point (AP), a wireless station (STA), and connected Profinet controllers and I / O devices. Both the AP and STA are configured in WDS bridging mode, abandoning the NAT rewriting mechanism for MAC addresses used in traditional routing modes. Detailed steps are as follows: Step 1: Establish a WDS wireless virtual interface; Both the AP and STA establish wireless virtual interfaces (VAPs) that support four-address 802.11 packet parsing. These VAPs use the WDS frame format, and their four-address structure is as follows: Address 1: The MAC address of the receiving STA, for example: 00:11:22:33:44:55; Address 2: The MAC address of the sending AP, for example: AA:BB:CC:DD:EE:FF; Address 3: The destination MAC address of the original 802.3 packet; Address 4: The source MAC address of the original 802.3 packet; This four-address encapsulation method ensures that the original Layer 2 MAC address information of the Profinet RT message is completely preserved during wireless transmission.

[0047] Step 2: Configure the wired interface and bridge; Create an 802.1q sub-interface eth0.0 on the wired interface eth0 at both the AP and STA ends. This sub-interface is specifically designed to identify and process 802.1Q packets with VLAN ID equal to 0, including: Profinet DCP device configuration protocol messages; periodic IO data messages; other Layer 2 priority frames.

[0048] Add the eth0.0 sub-interface and the wireless virtual interface VAP to the same bridge group (such as br0), and establish a Layer 2 forwarding path between the wired and wireless ports through the bridge forwarding table to realize the local packet forwarding function.

[0049] Step 3: Modify and swap chip configurations; Modifications were made to the wireless virtual interface at the driver level, specifically including: Added support for 802.1Q message forwarding; During the encapsulation of 802.3 packets into 802.11 packets, the virtual LAN tag information in the MAC header is retained; During the decapsulation of 802.11 packets into 802.3 packets, the integrity of the VLAN priority information is maintained; For scenarios where the switching chip is connected via a wired port, the switching chip is configured in transparent transmission mode to ensure that Layer 2 priority frames can be transmitted without loss.

[0050] Step 4: Configure service quality strategy; The wired side adopts the SP (Strict Priority) scheduling strategy, specifically configured as follows: Map Profinet RT packets with VLAN priority 5 and priority 6 to the highest priority queue; Set queue scheduling weights to ensure that high-priority messages are processed first. Configure buffer management policies to prevent message loss.

[0051] Step 5: Configure WMM mechanism; On the wireless side, WMM (Wi-Fi Multimedia) mechanism is enabled, mapping packets with virtual LAN priorities of 5 and 6 to AC_VO (Voice Access Class), with the following parameters set: AIFS arbitration inter-frame interval: 2 (shortest value); CWmin minimum contention window: 3; CWmax maximum contention window: 7; TXOP transmission opportunity: 3008μs.

[0052] The above configuration ensures that Profinet RT messages obtain the highest access priority and the lowest media access latency in wireless channel contention.

[0053] The data transmission process includes: Downlink transmission (controller → I / O device): The Profinet controller generates 802.3 RT frames with VLAN priority 6, where the source MAC is the controller address (e.g., 11:22:33:44:55:66) and the destination MAC is the I / O device address (e.g., 77:88:99:AA:BB:CC).

[0054] The AP's eth0.0 interface receives the frame and schedules it to the AC_VO queue according to the VLAN priority 6; The wireless virtual interface encapsulates 802.3 frames into quad-address 802.11 frames: Address 1: STA MAC address; Address 2: AP MAC address; Address 3: 77:88:99:AA:BB:CC (Destination MAC); Address 4: 11:22:33:44:55:66 (Source MAC).

[0055] The encapsulated 802.11 frames are transmitted in the 2.4 GHz or 5 GHz band via the AC_VO category.

[0056] The STA receives 802.11 frames and extracts the raw MAC address information from Address 3 and Address 4.

[0057] The STA reconstructs the original 802.3 frame, retains the VLAN priority label, and forwards it to the IO device through the high-priority queue of eth0.0.

[0058] Uplink transmission (IO device → controller): The uplink transmission process is the reverse of the downlink transmission. The 802.3 RT message sent by the IO device is encapsulated into a four-address 802.11 frame by the STA, transmitted to the AP through the wireless link, and finally decapsulated and forwarded to the Profinet controller.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for transmitting Profinet RT protocol messages via a wireless link, characterized in that, Includes the following steps: Establish wireless virtual interfaces that support four-address 802.11 packet parsing at wireless access points and wireless sites; Establish an 802.1q sub-interface, and add the 802.1q sub-interface and the wireless virtual interface to the bridge; Configure the wireless virtual interface to retain the VLAN tag and VLAN priority; Configure quality of service policies and wireless multimedia mechanisms to map packets, including those with virtual LAN priority, to high-priority queues and voice access categories; Receive 802.3 real-time packets including the virtual LAN priority, encapsulate the 802.3 real-time packets into four-address 802.11 frames and send them; The four-address 802.11 frames are received, decapsulated, and 802.3 real-time packets are obtained and forwarded.

2. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The establishment of a wireless virtual interface supporting four-address 802.11 packet parsing at the wireless access point and wireless station includes: The four addresses include the media access control address of the receiving wireless station, the media access control address of the sending wireless access point, the destination media access control address of the original message, and the source media access control address of the original message. The Layer 2 media access control address information of the original message is completely preserved and transmitted through the four addresses.

3. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 2, characterized in that, The wireless virtual interface adopts WDS bridging mode and transmits four-address 802.11 messages in WDS frame format. The first address is the media access control address of the receiving wireless station, the second address is the media access control address of the sending wireless access point, the third address is the destination media access control address of the original message, and the fourth address is the source media access control address of the original message.

4. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The configuration of the wireless virtual interface to retain the VLAN tag and VLAN priority includes: The driver of the wireless virtual interface is modified so that it retains the VLAN tag and VLAN priority in the Media Access Control header when converting 802.3 and 802.11 packets, and the switching chip connected to the wired port is configured to transparently transmit Layer 2 priority frames.

5. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 4, characterized in that, The driver modification for the wireless virtual interface includes: Add support for 802.1Q packet forwarding so that the wireless virtual interface can fully retain the VLAN priority information contained in the 802.1Q packet with the identifier 0 during the process of encapsulating 802.3 packets into 802.11 packets and decapsulating 802.11 packets into 802.3 packets.

6. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The configured Quality of Service (QoS) policy and wireless multimedia mechanism map packets, including those with virtual LAN priority, to high-priority queues and voice access categories, including: Configure a quality of service policy on the wired side to map packets with VLAN priority 5 and 6 to the highest priority queue. Enable the wireless multimedia mechanism on the wireless side to map packets with VLAN priority 5 and 6 to the voice access category.

7. The method for transmitting Profinet RT protocol messages via a wireless link as described in claim 6, characterized in that, The voice access category is configured with the shortest arbitration inter-frame interval and the smallest contention window, and the packets of the virtual LAN priorities 5 and 6 have the highest access priority and the smallest media access delay in wireless channel contention.

8. A method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The step of establishing an 802.1q sub-interface and adding the 802.1q sub-interface and the wireless virtual interface to the bridge includes: Establish an 802.1q sub-interface for identifying and forwarding Layer 2 priority frames; The 802.1q sub-interface and the wireless virtual interface are added to the bridge so that wired and wireless packets are forwarded locally on the device.

9. A method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The receiving of 802.3 real-time packets including the virtual LAN priority, encapsulating the 802.3 real-time packets into four-address 802.11 frames and sending them includes: The 802.3 real-time packets are scheduled to the voice access category queue according to the virtual LAN priority. The original Layer 2 Media Access Control address information of the 802.3 real-time message is encapsulated into the address field of a four-address 802.11 frame and transmitted via a wireless channel.

10. A method for transmitting Profinet RT protocol messages via a wireless link as described in claim 1, characterized in that, The process of receiving the four-address 802.11 frame, decapsulating the four-address 802.11 frame to obtain an 802.3 real-time packet, and forwarding it includes: Extract the original Layer 2 Media Access Control address information from the address field of the four-address 802.11 frames; The original Layer 2 Media Access Control address information is used to reconstruct 802.3 real-time packets and forward them through a high-priority wired queue.

Images