CAN star topology network structure
Through the CAN star topological network structure, the CAN relay nodes are used to optimize signal transmission and wiring, which solves the signal attenuation and delay problems of traditional CAN bus in multi-node wiring scenarios, and achieves more efficient data transmission and network reliability.
Patent Information
- Application Number
- CN202422255933.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-14
AI Technical Summary
In communication applications with complex wiring, traditional CAN buses have problems such as long signal transmission delay, large attenuation and high communication error rate. Especially in multi-node wiring scenarios, it is necessary to optimize the wiring method to improve network efficiency and reliability.
It adopts a CAN star topological network structure, and connects nodes to the CAN relay node through the CAN relay node, reduces signal transmission distance, simplifies wiring design, supports flexible network expansion and device node types, reduces the probability of communication errors, and improves network stability and fault tolerance.
It reduces signal attenuation and delay, simplifies the wiring process, improves the stability and accuracy of data transmission, enhances the reliability and flexibility of the network, and adapts to different communication needs and arrangements.
Smart Images
Figure CN223053035U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electronic circuits, and in particular to a CAN star topology network structure. Background Art
[0002] CAN (Controller Area Network) is a serial communication protocol bus for real-time applications. It supports distributed control systems and transmits signals through twisted pair cables. It is one of the most widely used field buses in the world. The CAN bus adopts multi-master mode, that is, multiple devices can be mounted on one bus and start sending messages when the bus is idle. The priority of the message is determined by the ID. The unit that wins the arbitration can continue to send messages, while the unit that loses the arbitration stops sending and switches to receiving.
[0003] Therefore, CAN communication is widely used in various industrial equipment fields as a communication method with long transmission distance and strong anti-interference performance. However, in some building-level and multi-node communication applications, traditional CAN communication often requires pulling wires back and forth between nodes due to the single wiring method. Excessive wiring distance will cause long signal transmission delay, large attenuation, and even high communication error rate. Therefore, it is particularly necessary to find an efficient CAN network wiring method. Utility Model Content
[0004] The present application provides a CAN star topology network structure. The technical solution is as follows:
[0005] According to one aspect of the present application, a CAN star topology network structure is provided, the structure comprising a CAN device node, a CAN module and a CAN bus;
[0006] Among the CAN device nodes, there is at least one CAN device node including n CAN modules, where n is a positive integer, and the CAN device node including the CAN modules serves as a CAN relay node;
[0007] Each CAN module in the CAN relay node is used for communication between upper and lower level CAN device nodes.
[0008] Optionally, the CAN devices included in the CAN relay node are divided into terminal node types and intermediate node types;
[0009] Under the terminal node type, the CAN device is connected to an upper-level CAN device node or a lower-level CAN device node, and the CAN device is used for the CAN device node to communicate with the upper-level CAN device node, or for the CAN device node to communicate with the lower-level CAN device node;
[0010] Under the intermediate node type, the CAN device is connected to a superior CAN device node and an inferior CAN device node, and the CAN device is used for communication between the superior CAN device node and the inferior CAN device node.
[0011] Optionally, in the control circuit of the CAN relay node, a controller and CAN isolation modules corresponding to each CAN device are included, and n CAN isolation modules are respectively connected to the controller.
[0012] Optionally, the CAN isolation module is used to convert the CAN port signal of the controller into a standard CAN level signal.
[0013] Optionally, in the structure of the controller, each CAN isolation module is further connected to a bidirectional TVS tube, and the bidirectional TVS tube is used to protect the connected CAN isolation module from electrostatic damage.
[0014] Optionally, in the structure of the controller, the bidirectional TVS tube is further connected to a terminal resistor, and the terminal resistor is used for impedance matching of the CAN bus.
[0015] Optionally, when the CAN device included in the CAN relay node has an intermediate node type, the controller included in the control circuit of the CAN relay node is further provided with a jumper pin;
[0016] When the jumper pin is not connected with a jumper cap, the CAN device is used as an intermediate node;
[0017] When the jumper pin is connected with a jumper cap, the CAN device is used as a terminal node.
[0018] Optionally, the CAN device of the intermediate node type is connected to the main CAN bus, and the CAN device of the terminal node type is connected to the branch CAN bus.
[0019] In this application, a CAN star topology network structure is provided, which has the following technical effects. By using star topology to replace the traditional linear topology, the signal transmission and wiring efficiency are optimized. On the one hand, signal attenuation and delay are reduced. The star topology connects nodes to CAN relay nodes, reducing the signal transmission distance, lowering signal attenuation and delay, and improving the stability and accuracy of data transmission. On the other hand, the wiring is simplified. Compared with the traditional CAN bus wiring, the star topology reduces the long-distance wiring requirements, avoids pulling wires back and forth between multiple nodes, and simplifies the wiring design and construction. On the one hand, there is flexible network expansion. The use of CAN relay nodes allows for flexible network expansion when needed, supports different types of device nodes, and facilitates dealing with different communication requirements and actual layout situations. On the other hand, the network reliability is also improved. By reducing the bus length and bifurcation points, the probability of communication errors is reduced. At the same time, the setting of relay nodes enhances the network stability and fault tolerance. Overall, it provides higher network efficiency and reliability in complex wiring application scenarios, overcoming the deficiencies of traditional CAN buses. Description of the Drawings
[0020] Figure 1 is a schematic structural diagram of a CAN star topology network structure provided by an exemplary embodiment of the present application;
[0021] Figure 2 is shown as a schematic structural diagram of a CAN relay node control circuit;
[0022] Figure 3 shows a simulation schematic diagram of the controller;
[0023] Figure 4 shows a PCB circuit diagram inside the controller;
[0024] Figure 5 shows a wiring diagram of a traditional CAN network in a single four-story building;
[0025] Figure 6 shows an implementation schematic diagram of a CAN star topology network structure in a building scenario. Detailed Implementation Modes
[0026] To make the objectives, technical solutions, and advantages of the present utility model clearer, the following will further describe the embodiments of the present utility model in detail with reference to the drawings.
[0027] As used herein, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.
[0028] Embodiment 1
[0029] Please refer to Figure 1 , which shows a schematic structural diagram of a CAN star topology network structure provided by an exemplary embodiment of the present application.
[0030] As Figure 1 shown, the CAN star topology network structure includes CAN device nodes, CAN modules, and a CAN bus.
[0031] Figure 1 The numbers of the CAN device nodes, CAN modules, and CAN bus shown in
[0032] do not limit the present application. Among the CAN device nodes, there is at least one CAN device node that contains n CAN modules, where n is a positive integer, and the CAN device node containing the CAN module is used as a CAN relay node.
[0033] Each CAN module in the CAN relay node is used for communication between upper and lower CAN device nodes.
[0034] However, during the process of each CAN module being used for communication between upper and lower CAN device nodes, it also has different device node communication functions according to different types of CAN devices. Figure 1
[0035] In a possible implementation manner, the CAN devices included in the CAN relay node are divided into a terminal node type and an intermediate node type. As
[0036] shown, CAN1 device and CAN2 device are of the terminal node type, and CAN3 device is of the intermediate node type. Figure 1 It should be noted that the CAN device of the intermediate node type functions as a terminal node type under the control component. In the following embodiments, the control component is taken as an example of a jumper pin for illustration.
[0037] Figure 1 As Figure 1As shown, under the said intermediate node type, the CAN device (i.e., CAN3) is connected to a superior CAN device node (i.e., CAN device node 4) and an inferior CAN device node (i.e., CAN device node 5). The CAN device (i.e., CAN3) is used for communication between the superior CAN device node (i.e., CAN device node 4) and the inferior CAN device node (i.e., CAN device node 5).
[0038] In summary, in Figure 1 , in this way, CAN device node 2 can achieve the construction of a CAN star topology network structure.
[0039] Generally speaking, in a CAN star topology network structure, each CAN device node can include several CAN modules. Among the CAN modules, some are used for communication with the upper-level node and are responsible for data reception; some communicate with the lower-level node and are responsible for data transmission or forwarding; some are located at the intermediate node and are responsible for data reception and transmission.
[0040] Therefore, different from the traditional CAN communication bus structure, in the CAN star topology network structure provided by this application, each CAN device node can be connected to a common CAN bus and used as a common device node, and can also be used as a CAN relay for data distribution and enhancement, so as to achieve star topology connection of the CAN network. The CAN star topology network structure can flexibly route the CAN network according to the actual situation of the implementation project, and can be used as a CAN relay for star wiring at the bifurcation. It avoids the detour of the CAN bus between different nodes, reduces the bus length, improves the accuracy of data transmission, and thus avoids the disadvantage of communication errors caused by signal attenuation when the traditional CAN bus is too long.
[0041] Embodiment 2
[0042] Next, the control circuit of the CAN relay node and the structure of the controller in the control circuit will be further disclosed.
[0043] As Figure 2 shown is a schematic diagram of the control circuit structure of the CAN relay node. The CAN relay node is the Figure 1 CAN device node 2 in Figure 2 . In the control circuit of the CAN relay node, it includes a controller and CAN isolation modules corresponding to each CAN device. The n CAN isolation modules are respectively connected to the controller. In Figure 2 , since the actual controller presents in the form of a single-chip microcomputer and the CAN isolation module presents in the form of a chip, the CAN isolation module is denoted by a CAN chip for illustration in
[0044] For the controller model, the embodiments of the present application do not limit this. For example, a single-chip microcomputer such as the STM32F413VGT6 model can be used. The main function is to realize CAN communication by outputting signals through the CAN port of the single-chip microcomputer. The selection of the single-chip microcomputer can be determined according to the actual situation.
[0045] Furthermore, the CAN isolation module is used to convert the CAN port signal of the controller into a standard CAN level signal. In the structure of the controller, each CAN isolation module is also connected with a bidirectional TVS tube, and the bidirectional TVS tube is used to protect the connected CAN isolation module from electrostatic damage. In the structure of the controller, the bidirectional TVS tube is also connected with a terminal resistor, and the terminal resistor is used for impedance matching of the CAN bus.
[0046] As mentioned above, when there is an intermediate node type among the CAN devices included in the CAN relay node, the controller included in the control circuit of the CAN relay node is also provided with a jumper pin. When the jumper pin is not connected with a jumper cap, the CAN device is used as an intermediate node; when the jumper pin is connected with a jumper cap, the CAN device is used as a terminal node.
[0047] Figure 3 The simulation schematic diagram of the controller is shown. Figure 4 The PCB circuit diagram inside the controller is shown.
[0048] Figure 3 and Figure 4 In, U4, U7 and U15 are CAN isolation modules, and their function is to convert the CAN port signals of the corresponding single-chip microcomputer of the controller into standard CAN level signals.
[0049] Figure 3 D4 - D9 in are shown as bidirectional TVS tubes; R6, R18 and R20 in the figure are terminal resistors, which are used for impedance matching of the CAN bus to improve signal quality; JP1 in the figure is a jumper pin.
[0050] In addition, CAN1_TXD / RXD, CAN2_TXD / RXD and CAN3_TXD / RXD in the figure are respectively connected to the 3 CAN ports of the selected single-chip microcomputer of the controller, and are respectively corresponding to Figure 1 the CAN1 module, CAN2 module and CAN3 module of the CAN device node 2 in.
[0051] To better illustrate the implementation effect of the CAN star topology network structure, as Figure 5 and 6 shown, Figure 5 the wiring diagram of the traditional CAN network in a single four-story building is shown. Figure 6Schematic diagram showing the implementation of a CAN star - topology network structure in a building scenario.
[0052] As Figure 5 shown, in the wiring diagram of a traditional CAN network within a single four - story building, there are 3 CAN nodes on each floor. They are connected by two long CAN_H and CAN_L lines. When the node in the lower - left corner of the first floor communicates with the node at the left end of the farthest third floor, due to the long distance between the nodes, using this structural solution will cause transmission delay. When the baud rate is relatively high, communication failures will occur. Therefore, at this time, the baud rate can only be reduced and the bus occupancy rate can be decreased to reduce the bit error rate. At the same time, due to the long bus, there will be a certain voltage drop on the bus, which will significantly reduce the bus level at the end. When the bus is too long, the level will drop to a degree that the CAN isolation module cannot recognize, resulting in communication failure.
[0053] And the situation in actual projects is often more complex than the above figure. For example, for a CAN node located in an isolated location, we even need to pull the CAN line there and then back, resulting in double the line length, which makes the communication quality deteriorate particularly severely.
[0054] As Figure 6 shown, this is a schematic diagram showing the implementation of a CAN star - topology network structure provided by this patent. Similarly, there are 12 CAN nodes distributed within a single four - story building. The nodes in the middle position of each floor are connected to form the main CAN bus. The nodes located on the main CAN bus are the main CAN nodes. We connect the CAN3 of each main CAN node to the main CAN bus. Then, the CAN1 and CAN2 of the main CAN nodes on each floor are used as terminal nodes to build branch CAN buses with the left and right branch nodes on the same floor respectively. In this way, it can be ensured that each CAN network is not too long, thus improving the communication quality.
[0055] In a possible implementation manner, when building the CAN star - topology network structure diagram, a main CAN bus is first built according to the actual node distribution and the communication frequency of each node, and then other nodes build branch CAN buses with the main CAN nodes on the main CAN bus. After that, a suitable maximum bus length is set to ensure the communication quality. That is, CAN devices of the intermediate node type are connected to the main CAN bus, and CAN devices of the terminal node type are connected to the branch CAN bus. The nodes at both ends of each CAN bus connect their CAN1 or CAN2 to the bus, and the nodes in the middle part of each CAN bus connect their CAN3 to the bus. Of course, technicians can further fork and build more branch CAN buses on each branch CAN bus according to requirements, and finally complete the construction of the star - topology network structure.
[0056] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application.
Claims
1. A CAN star topology network structure, characterized in that: The structure includes a CAN device node, a CAN module and a CAN bus; Among the CAN device nodes, there is at least one CAN device node including n CAN modules, where n is a positive integer, and the CAN device node including the CAN modules serves as a CAN relay node; Each CAN module in the CAN relay node is used for communication between upper and lower level CAN device nodes.
2. The structure according to claim 1, characterized in that: The CAN devices included in the CAN relay node are divided into terminal node type and intermediate node type; Under the terminal node type, the CAN device is connected to an upper-level CAN device node or a lower-level CAN device node, and the CAN device is used for the CAN device node to communicate with the upper-level CAN device node, or for the CAN device node to communicate with the lower-level CAN device node; In the intermediate node type, the CAN device is connected to an upper-level CAN device node and a lower-level CAN device node, and the CAN device is used for communication between the upper-level CAN device node and the lower-level CAN device node.
3. The structure according to claim 1, characterized in that: The control circuit of the CAN relay node includes a controller and CAN isolation modules corresponding to each CAN device, and n CAN isolation modules are respectively connected to the controller.
4. The structure according to claim 3, characterized in that The CAN isolation module is used to convert the CAN port signal of the controller into a standard CAN level signal.
5. The structure according to claim 4, characterized in that: In the structure of the controller, each CAN isolation module is also connected to a bidirectional TVS tube, and the bidirectional TVS tube is used to protect the connected CAN isolation module from being damaged by static electricity.
6. The structure according to claim 5, characterized in that In the structure of the controller, the bidirectional TVS tube is also connected to a terminal resistor, and the terminal resistor is used for impedance matching of the CAN bus.
7. The structure according to claim 2, characterized in that: When the CAN device included in the CAN relay node has an intermediate node type, the controller included in the control circuit of the CAN relay node is also provided with a jumper pin; When the jumper pin is not connected to the jumper cap, the CAN device is used as an intermediate node; When the jumper pin is connected to a jumper cap, the CAN device is used as a terminal node.
8. The structure according to claim 2, characterized in that The intermediate node type CAN device is connected to the main CAN bus, and the terminal node type CAN device is connected to the branch CAN bus.