Method and system for using CAN-FD bus with adaptive conversion rate

Abstract

The present invention provides a method and system for using a CAN-FD bus with an adaptive rate conversion, including: starting each node on the CAN-FD bus in a low-rate mode; making a designated master node on the CAN-FD bus detect whether a remote node is online; wherein the remote distance refers to a distance exceeding a set distance threshold; making the designated master node on the CAN-FD bus monitor the load rate of the bus in real time when it is working; if the remote node is online, or the load rate exceeds the load rate threshold, the master node makes each node on the CAN-FD bus switch to a high-rate mode; otherwise, the low-rate mode is maintained. The present invention can meet the needs of connecting long-distance nodes (such as measurement and control / curing nodes) and can meet the application requirements of multi-node control system communication for high bandwidth.

Description

Technical Field

[0001] The present invention relates to the technical field of controller area network with flexible data rate (CAN-FD), and in particular to a method and system for using a CAN-FD bus with adaptive rate conversion. Background Art

[0002] With the increasing number of electronic devices used in vehicles, users' requirements for vehicle network data transmission rate and bandwidth have increased exponentially. The original Controller Area Network (CAN) is increasingly unable to meet user needs in terms of transmission rate and bandwidth. The CAN-FD network can increase the transmission rate of the data domain. In addition, CAN-FD has expanded the length of the data domain, supporting a maximum of 64 bytes. The above two optimizations increase the bandwidth of the CAN-FD network, with a maximum rate of up to 10Mbit / s. The CAN-FD network inherits the main characteristics of the traditional CAN network, while making up for the shortcomings of the traditional CAN network in data transmission, bandwidth, and data domain length. As a result, the CAN-FD network has been widely used. For example, patent document CN110557309A discloses a CAN-FD bus automation control system and method based on hardware logic, which includes a host PC and a slave hardware circuit; the slave hardware circuit includes a microcontroller, a Bluetooth module, a USB3.1 module and a CAN-FD transceiver; the slave hardware circuit is connected to the PC via a USB3.1 cable or Bluetooth wireless, and the slave hardware circuit is connected to and communicates with the controlled node via the CAN-FD bus CANH and the CAN-FD bus CANL at the same time; the microcontroller is connected to at least four CAN-FD controllers, the TX pin and RX pin of each CAN-FD controller are respectively connected to the TX pin and RX pin of the CAN-FD transceiver, the CANH of the CAN-FD transceiver is connected to the CAN-FD bus CANH, and the CANL of the CAN-FD transceiver is connected to the CAN-FD bus CANL.

[0003] CAN-FD is a fieldbus, a serial communication bus technology that effectively supports multi-node distributed control or real-time control. The CAN-FD network can increase the transmission rate of the data domain and expand the length of the data domain (maximum support 64 bytes), increasing the CAN-FD network bandwidth, and the maximum rate can reach 10Mbit / s.

[0004] However, the CAN-FD bus transmits data via two signal lines in the form of differential signals. The maximum transmission bandwidth of CAN-FD and the maximum transmission distance of the bus are mutually restricted, which is generally an important constraint in network topology design. In actual applications, there is a scenario where the same bus network sometimes needs to transmit data over long distances, and also needs to transmit data at a high rate when disconnecting distant nodes to reduce the bus load rate, etc.

[0005] Therefore, a method of adaptive conversion rate is needed, which can not only meet the needs of connecting long-distance nodes (such as measurement and control / hardening nodes), but also meet the application requirements of multi-node control system communication for high bandwidth. Summary of the invention

[0006] In view of the defects in the prior art, an object of the present invention is to provide a method and system for using a CAN-FD bus with an adaptive rate change.

[0007] A method for using a CAN-FD bus with an adaptive conversion rate provided by the present invention includes:

[0008] Step 1: Start each node on the CAN-FD bus in low-rate mode;

[0009] Step 2: Let the designated master node on the CAN-FD bus detect whether the remote node is online; where the remote distance refers to a distance exceeding a set distance threshold; let the designated master node on the CAN-FD bus monitor the load rate of the bus in real time when it is working;

[0010] Step 3: If the remote node is online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to high-rate mode; otherwise, it maintains low-rate mode.

[0011] Preferably, the arbitration domain rate in the high rate mode is higher than the arbitration domain rate in the low rate mode.

[0012] Preferably, in step 2, after the master node on the CAN-FD bus is started, a handshake frame is sent to other nodes, and a handshake response frame corresponding to the handshake frame is used to determine whether the pluggable remote node is online.

[0013] Preferably, in step three:

[0014] If the master node determines that the remote node is not online, the master node sends three rate switching broadcast frames in succession, and sends a rate switching broadcast frame to other nodes indicating switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-rate mode;

[0015] If the master node determines that the communication load rate of the CAN-FD bus is greater than 50% and the rate can be increased under the current transmission distance, the master node sends three consecutive rate switching broadcast frames to indicate switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If no rate switching cancel frame is received within the set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; among them, after the set time period after the rate switching response frames of all nodes are received normally, the master node switches to high-rate mode.

[0016] Preferably, in the step 2, the master node is instructed to detect the online status of all nodes in the CAN-FD bus network, and determine the distance of the online farthest node; wherein, the determination of the distance of the online farthest node comprises: the master node of the CAN-FD bus network broadcasts a handshake frame, monitors the reply frame corresponding to the handshake frame of each node; confirms the identity of the online node according to the reply frame; obtains the known node distance corresponding to the identity according to the node identity known in the network topology design, and obtains the distance of the online farthest node;

[0017] In the step three, the load rate of the monitoring bus during operation includes: the online nodes report the cycle and data length of their respective message transmissions to the master node through handshake frame reply frames; the master node calculates the maximum available transmission bandwidth while meeting the bus load rate requirements based on its own data transmission conditions.

[0018] A CAN-FD bus control system with adaptive conversion rate provided by the present invention comprises:

[0019] The first processing module: starts each node on the CAN-FD bus in a low-rate mode;

[0020] The second processing module: enables the designated master node on the CAN-FD bus to detect whether the remote node is online; wherein the remote distance refers to a distance exceeding a set distance threshold; enables the designated master node on the CAN-FD bus to monitor the load rate of the bus in real time when the bus is working;

[0021] The third processing module: If the remote node is online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to the high-rate mode; otherwise, the low-rate mode is maintained.

[0022] Preferably, the arbitration domain rate in the high rate mode is higher than the arbitration domain rate in the low rate mode.

[0023] Preferably, in the second processing module, after the master node on the CAN-FD bus is started, a handshake frame is sent to other nodes, and a handshake response frame corresponding to the handshake frame is used to determine whether the pluggable remote node is online.

[0024] Preferably, in the third processing module:

[0025] If the master node determines that the remote node is not online, the master node sends three rate switching broadcast frames in succession, and sends a rate switching broadcast frame to other nodes indicating switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-rate mode;

[0026] If the master node determines that the communication load rate of the CAN-FD bus is greater than 50% and the rate can be increased under the current transmission distance, the master node sends three consecutive rate switching broadcast frames to indicate switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If no rate switching cancel frame is received within the set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; among them, after the set time period after the rate switching response frames of all nodes are received normally, the master node switches to high-rate mode.

[0027] Preferably, in the second processing module, the master node is instructed to detect the online status of all nodes in the CAN-FD bus network and determine the distance of the online farthest node; wherein, the determination of the distance of the online farthest node comprises: the master node of the CAN-FD bus network broadcasts a handshake frame and monitors the reply frame corresponding to the handshake frame of each node; confirms the identity of the online node according to the reply frame; obtains the known node distance corresponding to the identity according to the node identity known during the network topology design, and obtains the distance of the online farthest node;

[0028] In the third processing module, the load rate of the monitoring bus when working includes: the online nodes report the cycle and data length of their respective message transmissions to the master node through handshake frame reply frames; the master node calculates the maximum available transmission bandwidth while meeting the bus load rate requirements based on its own data transmission conditions.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention mainly provides a CAN-FD bus usage scheme with an adaptive rate change to meet the application requirements of the CAN-FD bus communication network, which sometimes needs to transmit data over long distances and needs to transmit data at a high rate when the remote nodes are disconnected.

[0031] 2. The purpose of the present invention is to solve the application requirements of long-distance data transmission in the CAN-FD bus communication network, and high-speed data transmission when the remote nodes are disconnected.

[0032] 3. The present invention dynamically adjusts the bus transmission bandwidth to meet the needs of actual applications by detecting the existence of pluggable long-distance nodes and the bus load rate. It can be used in the design of CAN-FD bus networks with long-distance measurement and control nodes or program-cured upload nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0034] Figure 1 It is a topological structure diagram of the CAN-FD bus communication network in high-rate / low-rate mode of the present invention.

[0035] Figure 2 It is a flow chart of the CAN-FD network adaptive rate conversion process in the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0037] The present invention belongs to the technical field of Controller Area Network with Flexible Data rate (CAN-FD), and specifically relates to a method and system for using a CAN-FD bus with adaptive rate conversion. The purpose of the present invention is to solve the application requirements of the CAN-FD bus communication network that sometimes requires long-distance data transmission and high-speed data transmission when the remote node is disconnected. The present invention dynamically adjusts the bus transmission bandwidth to meet the actual application needs by detecting whether a pluggable remote node exists and the bus load rate:

[0038] On the one hand, all nodes on the CAN-FD bus start in low-rate mode, and the master node detects whether a remote node exists through a detection frame; if so, it works in low-rate mode; otherwise, it sends a rate reset command to switch to high-rate mode;

[0039] On the other hand, the master node monitors the communication of the CAN-FD bus in real time and calculates the bus load rate. If the load rate exceeds the recommended threshold, it sends a rate reset command to switch to high-rate mode.

[0040] Through the above scheme, the communication rate can be selected according to the actual scenario, and the reliability of communication can be improved as much as possible while meeting the usage needs.

[0041] A method for using a CAN-FD bus with an adaptive conversion rate provided by the present invention includes:

[0042] Step 1: Start each node on the CAN-FD bus in low-rate mode;

[0043] Step 2: Let the designated master node on the CAN-FD bus detect whether the remote node is online; where the remote distance refers to a distance exceeding a set distance threshold; let the designated master node on the CAN-FD bus monitor the load rate of the bus in real time when it is working;

[0044] Step 3: If the remote node is online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to high-rate mode; otherwise, it maintains low-rate mode.

[0045] like Figure 1As shown, it is a topological structure diagram of the CAN-FD bus communication network in high-speed / low-speed mode of the present invention. In this embodiment, CAN-FD node 1 in the figure is a central control node (master node), node R is a long-distance node, which is a measurement and control-curing node in this network, and its transmission distance is 23.0 meters; node 2, node 3, etc. are short-distance nodes. When there is a measurement and control-curing node in the CAN-FD network, the network works in a low-rate mode, and the arbitration domain and data domain rates are 1Mbit / s; and when the measurement and control-curing node is not online, the network works in a high-rate mode, the arbitration domain rate is 1Mbit / s, and the data domain rate is 4Mbit / s. The communication rate in the high-rate mode is higher than the communication rate in the low-rate mode.

[0046] In step 1, each node on the CAN-FD bus is started in low-rate mode, and the distance of the farthest node is set as the set distance threshold when the bus is designed. For example, if the distance of the far node is 23 meters, the startup rate of each node can be designed to be 1Mb in the arbitration domain and 1Mb in the data domain to be compatible with long-distance transmission.

[0047] In the step 2, after the master node on the CAN-FD bus is started, it sends a handshake frame to other nodes, and determines whether the pluggable remote node is online through the handshake response frame.

[0048] In the step three, 1) if the master node determines that the remote node is not online. The master node sends three rate switching broadcast frames in succession, and switches to high-speed mode 10ms after receiving the normal rate switching response frames of all nodes. After receiving the rate switching instruction, other nodes send three frames of rate switching response frames. If the rate switching cancellation frame is not received within 10ms, it switches to high-speed mode and waits for the handshake frame of the master node's high-speed mode. 2) If the master node determines that the communication load rate of the bus is greater than 50% and the rate can be increased under the current transmission distance. The master node sends three rate switching broadcast frames in succession, and switches to high-speed mode 10ms after receiving the normal rate switching response frames of all nodes. After receiving the rate switching instruction, other nodes send three frames of rate switching response frames. If the rate switching cancellation frame is not received within 10ms, it switches to high-speed mode and waits for the handshake frame of the master node's high-speed mode.

[0049] The master node monitors the distance to the farthest node among the nodes on the CAN-FD bus and the bus load rate through the detection frame, and adaptively changes the optimal transmission rate.

[0050] The present invention will be described in more detail below. Figure 2 As shown, it is a CAN-FD network adaptive rate conversion processing flow chart in the present invention, which specifically includes the following steps:

[0051] S0: After the CAN-FD network is started, the master node sends a handshake frame in broadcast mode.

[0052] S0a: After the CAN-FD network is started, all online slave nodes work normally at the initial transmission rate, where the initial transmission rate is a low rate.

[0053] S1a: All online slave nodes respond by sending handshake reply frames.

[0054] S1: The master node determines the maximum distance of the online node and calculates the load rate of the CAN-FD bus network through the handshake reply frame content.

[0055] S2: The master node determines whether the transmission rate needs to be switched based on the calculation result and the transmission distance. If necessary, S3: The master node sends three rate switching broadcast frames in succession; otherwise: jump to S8: The CAN-FD bus network works at the initial rate.

[0056] S2a: All online slave nodes in the CAN-FD bus network respond with a rate switch response frame.

[0057] S4: If the master node receives the rate switching response frames from all online nodes within 10ms after sending the rate switching frame, then S6: the master node switches to the adapted transmission rate after 10ms; otherwise, execute S5: the master node sends a rate switching cancel frame and reports the network failure.

[0058] S7: The master node communicates with each node in the new rate mode.

[0059] S3a: If each slave node in the network does not receive the rate switching cancellation frame within 10ms, then S4a: after 10ms, it switches to the specified rate according to the requirements of the master node rate switching frame. Otherwise, it returns to S0a.

[0060] S5a: Each slave node in the network receives the data frame of the new rate of the master node, then S6a: all online slave nodes work normally in the new rate mode.

[0061] In summary, the invention is based on the method of adaptively changing the rate according to the application scenario of the CAN-FD bus, which can solve the application requirements of the CAN-FD bus communication network that sometimes needs to transmit data over long distances and needs to transmit data at a high rate when the distant nodes are disconnected; and by adjusting the bandwidth as much as possible to reduce the load rate, it optimizes the problem of low-priority messages in the CAN-FD bus failing in multiple competitions, resulting in the inability to send data in time, which can improve the stability of message data transmission and reduce the safety hazards of bus use.

[0062] The present invention also provides a CAN-FD bus control system with an adaptive conversion rate. A person skilled in the art can implement the CAN-FD bus control system with an adaptive conversion rate by executing the step flow of the CAN-FD bus control method with an adaptive conversion rate, that is, the CAN-FD bus control method with an adaptive conversion rate can be understood as a preferred implementation of the CAN-FD bus control system with an adaptive conversion rate.

[0063] A CAN-FD bus control system with adaptive conversion rate provided by the present invention comprises:

[0064] The first processing module: starts each node on the CAN-FD bus in a low-rate mode;

[0065] The second processing module: instructs the designated master node on the CAN-FD bus to detect whether the long-distance node is online; wherein, the long distance refers to a distance exceeding a set distance threshold; instructs the designated master node on the CAN-FD bus to monitor the load rate of the bus in real time when it is working; the monitoring of the load rate of the bus when it is working includes: the online node replies to the frame through a handshake frame, and reports the period and data length of each message transmission to the master node; the master node calculates the maximum available transmission bandwidth while meeting the bus load rate requirement based on its own data transmission situation.

[0066] The third processing module: If the remote node is online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to the high-rate mode; otherwise, the low-rate mode is maintained.

[0067] The arbitration domain rate in the high-rate mode is higher than the arbitration domain rate in the low-rate mode.

[0068] In the second processing module, after the master node on the CAN-FD bus is started, it sends a handshake frame to other nodes, and determines whether the pluggable remote node is online through the handshake response frame corresponding to the handshake frame. In the second processing module, the master node is instructed to detect the online status of all nodes in the CAN-FD bus network and determine the distance of the farthest online node; wherein, the determination of the distance of the farthest online node includes: the master node of the CAN-FD bus network broadcasts a handshake frame and monitors the reply frames corresponding to the handshake frames of each node; confirms the identity of the online node based on the reply frame; obtains the known node distance corresponding to the identity based on the node identity known during the network topology design, and obtains the distance of the farthest online node;

[0069] In the third processing module: if the master node determines that the remote node is not online, the master node sends three rate switching broadcast frames in succession, and sends a rate switching broadcast frame indicating switching to high-speed mode to other nodes; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-speed mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-speed mode; if the master node determines that the communication load rate of the CAN-FD bus is greater than 50% and the rate can be increased under the current transmission distance, the master node sends three consecutive rate switching broadcast frames indicating switching to high-speed mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-speed mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-speed mode.

[0070] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0071] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for using a CAN-FD bus with an adaptive conversion rate, characterized in that: include: Step 1: Start each node on the CAN-FD bus in low-rate mode; Step 2: Let the designated master node on the CAN-FD bus detect whether the remote node is online; where the remote distance refers to a distance exceeding a set distance threshold; let the designated master node on the CAN-FD bus monitor the load rate of the bus in real time when it is working; Step 3: If the remote node is not online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to high-rate mode; otherwise, it maintains low-rate mode.

2. The method for using the CAN-FD bus with adaptive rate conversion according to claim 1, characterized in that: The arbitration domain rate in the high-rate mode is higher than the arbitration domain rate in the low-rate mode.

3. The method for using the CAN-FD bus with adaptive rate conversion according to claim 1, characterized in that: In the step 2, after the master node on the CAN-FD bus is started, it sends a handshake frame to other nodes, and determines whether the pluggable remote node is online through the handshake response frame corresponding to the handshake frame.

4. The method for using the CAN-FD bus with adaptive rate conversion according to claim 1, characterized in that: In step three: If the master node determines that the remote node is not online, the master node sends three rate switching broadcast frames in succession, and sends a rate switching broadcast frame to other nodes indicating switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-rate mode; If the master node determines that the communication load rate of the CAN-FD bus is greater than 50% and the rate can be increased under the current transmission distance, the master node sends three consecutive rate switching broadcast frames to indicate switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If no rate switching cancel frame is received within the set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; among them, after the set time period after the rate switching response frames of all nodes are received normally, the master node switches to high-rate mode.

5. The method for using the CAN-FD bus with adaptive rate conversion according to claim 1, characterized in that: In the step 2, the master node is instructed to detect the online status of all nodes in the CAN-FD bus network and determine the distance of the online farthest node; wherein, the determination of the distance of the online farthest node includes: the master node of the CAN-FD bus network broadcasts a handshake frame and monitors the reply frame corresponding to the handshake frame of each node; confirms the identity of the online node according to the reply frame; obtains the known node distance corresponding to the identity according to the node identity known during the network topology design, and obtains the distance of the online farthest node; In the step three, the load rate of the monitoring bus during operation includes: the online nodes report the cycle and data length of their respective message transmissions to the master node through handshake frame reply frames; the master node calculates the maximum available transmission bandwidth while meeting the bus load rate requirements based on its own data transmission conditions.

6. A CAN-FD bus control system with adaptive conversion rate, characterized in that: include: The first processing module: starts each node on the CAN-FD bus in a low-rate mode; The second processing module: enables the designated master node on the CAN-FD bus to detect whether the remote node is online; wherein the remote distance refers to a distance exceeding a set distance threshold; enables the designated master node on the CAN-FD bus to monitor the load rate of the bus in real time when the bus is working; The third processing module: If the remote node is not online, or the load rate exceeds the load rate threshold, the master node switches each node on the CAN-FD bus to the high-rate mode; otherwise, the low-rate mode is maintained.

7. The CAN-FD bus control system with adaptive conversion rate according to claim 6, characterized in that: The arbitration domain rate in the high-rate mode is higher than the arbitration domain rate in the low-rate mode.

8. The CAN-FD bus control system with adaptive conversion rate according to claim 6, characterized in that: In the second processing module, after the master node on the CAN-FD bus is started, a handshake frame is sent to other nodes, and a handshake response frame corresponding to the handshake frame is used to determine whether the pluggable remote node is online.

9. The CAN-FD bus control system with adaptive conversion rate according to claim 6, characterized in that: In the third processing module: If the master node determines that the remote node is not online, the master node sends three rate switching broadcast frames in succession, and sends a rate switching broadcast frame to other nodes indicating switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If other nodes do not receive a rate switching cancellation frame within a set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; wherein, after a set time period after receiving the rate switching response frames of all nodes as normal, the master node switches to high-rate mode; If the master node determines that the communication load rate of the CAN-FD bus is greater than 50% and the rate can be increased under the current transmission distance, the master node sends three consecutive rate switching broadcast frames to indicate switching to high-rate mode; after receiving the rate switching broadcast frame, other nodes send three frames of rate switching response frames. If no rate switching cancel frame is received within the set time period, they switch to high-rate mode and wait for the handshake frame of the master node's high-speed mode; among them, after the set time period after the rate switching response frames of all nodes are received normally, the master node switches to high-rate mode.

10. The CAN-FD bus control system with adaptive conversion rate according to claim 6, characterized in that: In the second processing module, the master node is instructed to detect the online status of all nodes in the CAN-FD bus network and determine the distance of the online farthest node; wherein, the determination of the distance of the online farthest node includes: the master node of the CAN-FD bus network broadcasts a handshake frame and monitors the reply frame corresponding to the handshake frame of each node; confirms the identity of the online node according to the reply frame; obtains the known node distance corresponding to the identity according to the node identity known in the network topology design, and obtains the distance of the online farthest node; In the third processing module, the load rate of the monitoring bus when working includes: the online nodes report the cycle and data length of their respective message transmissions to the master node through handshake frame reply frames; the master node calculates the maximum available transmission bandwidth while meeting the bus load rate requirements based on its own data transmission conditions.

Images