Extensible PLC redundancy CAN communication system
By designing a redundant PLC communication system using EtherCAT bus and CAN communication cards, employing ring networking and redundant interfaces, and combining it with an FPGA chip processor, the problems of high MCU load and poor FPGA user configurability were solved, achieving efficient and reliable PLC communication.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XIAN THERMAL POWER RES INST CO LTD
- Filing Date
- 2025-05-28
- Publication Date
- 2026-06-05
AI Technical Summary
In existing PLC communication systems, the MCU approach has a high load and cannot meet the requirements for interface expansion and redundancy, resulting in a large number of packet loss during burst transmission. When using FPGA and IP cores, the user configurability is poor and it cannot meet the implementation of specific functions.
A scalable PLC redundant communication system was designed, which includes EtherCAT bus, CAN bus and CAN communication card. Each communication card includes a communication chip, controller, processor, CAN transceiver and peripheral interface circuit. It adopts ring networking and redundant interface design, and uses FPGA chip for message processing to reduce MCU load and improve system reliability.
It effectively reduced the controller load, improved system reliability and transmission efficiency, met the application requirements of complex scenarios, solved the problems of high load and packet loss, and achieved efficient message processing.
Smart Images
Figure CN224329472U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of PLC communication technology, specifically relating to an expandable PLC redundant CAN communication system. Background Technology
[0002] CAN bus communication has the advantages of long transmission distance, high transmission rate, stable transmission signal and low cost, and is widely used in automotive and industrial control fields.
[0003] In the field of wind power PLC communication technology, the existing CAN bus communication typically includes the following two methods:
[0004] 1. Using an MCU with a built-in CAN controller to implement CAN bus communication, the communication between the host computer and the device relies on the MCU's built-in CAN controller. This method not only places relatively high demands on the MCU, requiring it to have its own CAN controller, but also limits the number of CAN controllers available, failing to meet the requirements for interface expansion and redundancy. Furthermore, its communication performance cannot handle situations involving a large number of burst transmissions of messages. This method is also prone to packet loss due to buffer limitations. Moreover, using an MCU not only results in high load but also suffers from the problem of packet loss during large-scale burst transmissions.
[0005] 2. A system using an MCU and FPGA to implement CAN bus communication typically employs Xilinx-packaged IP (Intellectual Property) cores. This method only works with Xilinx-manufactured FPGAs and is not supported by other manufacturers. Furthermore, this method is prone to packet loss during bursts of large-scale message transmission. Additionally, the use of IP cores results in poor user configurability and cannot meet specific functional requirements. Utility Model Content
[0006] The purpose of this invention is to provide a scalable PLC redundant CAN communication system to solve the problem of high load in the existing technology that uses MCU.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] In the first aspect, this utility model provides an expandable PLC redundant CAN communication system, including an EtherCAT bus, a CAN bus and several CAN communication cards. Each CAN communication card has a CAN interface, and the CAN interface of each CAN communication card is connected to the corresponding CAN bus. Each CAN bus is connected to a device that supports the CAN bus protocol.
[0009] Each CAN communication card includes a communication chip, controller, processor, CAN transceiver, and peripheral interface circuitry.
[0010] The communication chip is used for data interaction with the controller and the host computer;
[0011] The controller is used to configure the registers inside the processor, and the controller is also used to monitor the status of the CAN transceiver link inside the processor.
[0012] The processor is used to interact with the controller, and is also used to receive the controller's configuration results and the monitoring results of the CAN transceiver link status. The processor is also used to expand the CAN interface.
[0013] The CAN transceiver is used to convert the digital signal output by the processor into a differential signal that can be transmitted on the CAN bus.
[0014] The peripheral interface circuit is used to realize communication connection with devices that support the CAN bus protocol.
[0015] A further improvement of this invention is that the CAN interfaces of each CAN communication card are redundant.
[0016] A further improvement of this invention is that the two CAN communication cards are redundant with each other, and each CAN communication card is connected to the same CAN bus through a redundant CAN interface.
[0017] A further improvement of this invention is that each CAN communication card is networked in a ring network configuration.
[0018] A further improvement of this invention is that the communication chip is a communication chip that supports the EtherCAT bus protocol.
[0019] A further improvement of this invention is that the controller is an MCU chip.
[0020] A further improvement of this invention is that the processor is an FPGA chip.
[0021] A further improvement of this utility model is that the communication chip is connected to the controller, the controller is connected to the processor, the CAN transceiver is connected to the processor, the peripheral interface circuit is connected to the CAN transceiver, and the peripheral interface circuit is also connected to the communication chip.
[0022] A further improvement of this invention is that the communication chip is connected to the controller via an SPI interface, the controller is connected to the processor via a QSPI interface, the peripheral interface circuit is connected to the CAN transceiver via a CAN bus, and the peripheral interface circuit is also connected to the communication chip via an RJ45 interface.
[0023] A further improvement of this invention is that the device capable of supporting the CAN bus protocol is a motor-driven device.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] Compared to existing scalable PLC redundant CAN communication systems, the scalable PLC redundant CAN communication system proposed in this invention designs an EtherCAT bus, a CAN bus, and several CAN communication cards. Each CAN communication card has a CAN interface, and the CAN interface of each CAN communication card connects to a corresponding CAN bus. Each CAN bus can be connected to devices that support the CAN bus protocol. Each CAN communication card includes a communication chip, a controller, a processor, a CAN transceiver, and peripheral interface circuitry. It is evident that this invention uses the processor and controller in conjunction to reduce the controller's load, thereby effectively lowering the controller's load rate and effectively solving the problem of high load associated with existing MCU-based systems.
[0026] Furthermore, this utility model also discloses that the CAN interfaces of each CAN communication card are redundant, which can ensure that if one CAN interface fails, the other CAN interface can maintain normal communication, thereby improving the reliability of the entire communication system (a communication system composed of EtherCAT bus, CAN bus and several CAN communication cards).
[0027] Furthermore, this utility model also discloses that the networking mode of each CAN communication card is a ring network. The ring network not only has high transmission efficiency, but also is easy to expand. When a new node is added, it only needs to be connected to the ring without affecting other nodes. Compared with other networking methods (mesh), the cost is relatively low, making it suitable for some scenarios with limited budgets. Moreover, the ring network has high reliability. Compared with the chain network, the ring network can still work normally in the event of a network outage.
[0028] Furthermore, this utility model also discloses that the two CAN communication cards are redundant with each other. The redundant connection of the two CAN cards can ensure that if one CAN communication card fails, the other CAN communication card can maintain normal communication, thereby improving the reliability of the entire communication system (a communication system composed of EtherCAT bus, CAN bus and several CAN communication cards).
[0029] Furthermore, this utility model discloses that the processor is an FPGA chip. FPGA chips have relatively good programmability, which can meet the application needs of users in complex scenarios, thus effectively solving the problem of poor user configurability and inability to meet the implementation needs of specific functions when using IP cores. Moreover, the FPGA chip adopts a parallel approach, resulting in fast message processing speed. The FPGA chip supports message transmission and reception status monitoring, which can meet the application scenarios with high message throughput, thus effectively solving the problem of packet loss during sudden transmission of a large number of messages. Attached Figure Description
[0030] Figure 1 This is a diagram showing the external connection structure of the expandable PLC redundant CAN communication system of this utility model;
[0031] Figure 2 This is a diagram showing the internal connection structure of the CAN communication card in the expandable PLC redundant CAN communication system of this utility model. Detailed Implementation
[0032] To further understand the present invention, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not intended to limit the scope of the invention.
[0033] This invention proposes a scalable PLC redundant CAN communication system, which includes an EtherCAT bus, a CAN bus, and several CAN communication cards. Each CAN communication card has a CAN interface, which connects to a corresponding CAN bus. Each CAN bus can be connected to devices that support the CAN bus protocol. Each CAN communication card includes a communication chip, a controller, a processor, a CAN transceiver, and peripheral interface circuitry. Compared to existing technologies, this invention effectively solves the problem of high load associated with MCU-based systems.
[0034] Example 1:
[0035] This embodiment discloses a scalable PLC redundant CAN communication system. The external connection structure diagram of the scalable PLC redundant CAN communication system and the internal connection structure diagram of the CAN communication card in the scalable PLC redundant CAN system are shown below. Figure 1As shown, the technical solution of this embodiment is described in detail below:
[0036] This embodiment's scalable PLC redundant CAN communication system includes an EtherCAT bus, a CAN bus, and several CAN communication cards. Figure 1 In this context, CAN cards are referred to as CAN card 1, CAN card 2, and CAN card n. Each CAN communication card has a CAN interface, and the CAN interface of each CAN communication card is connected to the corresponding CAN bus. Figure 1 In this embodiment, CAN bus 1, CAN bus 2, and CAN bus i are used to represent the CAN bus. Each CAN bus is connected to a device that supports the CAN bus protocol (in this embodiment, the device that supports the CAN bus protocol is a motor-driven device). Figure 1 In this configuration, CAN bus 1 connects to devices 1, 2, and j; CAN bus 2 connects to devices 1, 2, and k; and CAN bus i connects to devices 1, 2, and m. This allows users to control field devices (devices supporting the CAN bus protocol) via the EtherCAT bus. Each CAN communication card has redundant CAN interfaces, ensuring that if one CAN interface fails, the other can maintain communication, thus improving the reliability of the entire communication system (composed of the EtherCAT bus, CAN bus, and several CAN communication cards).
[0037] Each CAN communication card includes a communication chip (in this embodiment, the communication chip is a communication chip that supports the EtherCAT bus protocol, also called an EtherCAT communication chip), a controller (in this embodiment, the controller is an MCU chip, also called an MCU), a processor (in this embodiment, the processor is an FPGA chip, also called an FPGA), a CAN transceiver, and peripheral interface circuits.
[0038] The communication chip is used for data interaction with the controller and the host computer.
[0039] The controller is used to configure the registers inside the processor and also to monitor the status of the CAN transceiver link inside the processor.
[0040] The processor is used for data interaction with the controller. It also receives configuration results from the controller and monitoring results of the CAN transceiver link status. Furthermore, the processor expands the CAN interface. The CAN interface is expandable, allowing for flexible networking and meeting diverse device needs. In this embodiment, the number of CAN communication cards can be set according to actual requirements.
[0041] A CAN transceiver is used to convert digital signals output by a processor into differential signals that can be transmitted on a CAN bus.
[0042] Peripheral interface circuits are used to implement communication connections with devices that support the CAN bus protocol.
[0043] The processor (FPGA chip) will be described in detail below:
[0044] In this embodiment, the FPGA chip allocates a memory area for each CAN interface. The FPGA chip stores the data from different interfaces sent by the MCU chip into the corresponding memory area. The MCU chip reads data from the corresponding memory according to the address of each memory area. The FPGA chip reads data from the memory of each CAN interface, encapsulates it into a CAN protocol message, and sends the CAN protocol message to the CAN transceiver. The FPGA chip receives the CAN message from the CAN transceiver, unpacks it to obtain the data, and stores the data in the corresponding CAN interface's memory area for the MCU chip to read.
[0045] The following provides a detailed explanation of the connection relationships between the communication chip, controller, processor, CAN transceiver, and peripheral interface circuits:
[0046] The communication chip (EtherCAT communication chip) is connected to the controller (MCU chip), the controller (MCU chip) is connected to the processor (FPGA chip), the CAN transceiver is connected to the processor (FPGA chip), the peripheral interface circuit is connected to the CAN transceiver, and the peripheral interface circuit is also connected to the communication chip (EtherCAT communication chip).
[0047] Specifically, the communication chip (EtherCAT communication chip) connects to the controller (MCU controller) via an SPI interface, the controller (MCU chip) connects to the processor (FPGA chip) via a QSPI interface, and the peripheral interface circuit connects to the CAN transceiver via a CAN bus (also called CAN). Figure 2 The EtherCAT network (also called EtherCAT) also connects to the communication chip (EtherCAT communication chip) via an RJ45 interface. The RJ45 interface and the communication chip (EtherCAT communication chip) are connected via EPO and EP1 interfaces. The FPGA chip connects to the CAN transceiver via FP0, FP1, FP2, FP3, FPi, and FPj interfaces. The FP0 and FP1 interfaces are redundant, as are the FP2 and FP3 interfaces, and the FPi and FPj interfaces.
[0048] The overall redundancy logic of this scalable PLC redundant CAN communication system is described as follows:
[0049] During normal operation, the main interface of the primary card is active. When the primary interface fails, the backup interface is used. When the primary card fails, or when both the primary and backup interfaces of the primary card connected to the same CAN bus fail, the backup card begins to operate.
[0050] In this embodiment, each CAN communication card is networked in a ring network configuration. Ring networks offer high transmission efficiency and are easily expandable. When a new node joins, it simply connects to the ring without affecting other nodes. Compared to other networking methods (mesh), the cost is relatively low, making it suitable for scenarios with limited budgets. Furthermore, ring networks offer high reliability; compared to chain networks, they can still function normally even in the event of a network outage.
[0051] In this embodiment, the two CAN communication cards are redundant with each other, and each CAN communication card is connected to the same CAN bus through redundant CAN interfaces. Figure 1 The ellipse at marker (A) indicates that the two CAN interfaces are redundant. Figure 1 The ellipse marked (B) indicates that CAN card 1 and CAN card 2 are redundant. The redundant connection of the two CAN cards can ensure that if one CAN communication card fails, the other CAN communication card can maintain normal communication, thus improving the reliability of the entire communication system (a communication system composed of EtherCAT bus, CAN bus and several CAN communication cards).
[0052] This invention relates to a scalable PLC redundant CAN communication system. The CAN interface can be expanded, meaning the FPGA can be expanded to include multiple CAN interfaces, resulting in relatively good economic efficiency. The FPGA chip in this system employs a parallel processing method, leading to fast message processing speed. Furthermore, the FPGA chip supports message transmission and reception status monitoring, meeting the needs of applications with high message throughput. This scalable PLC redundant CAN communication system combines the FPGA chip and the MCU chip, effectively reducing the MCU chip's load rate. Moreover, the FPGA chip's relatively good programmability can meet the needs of users in complex application scenarios.
[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.
Claims
1. A scalable PLC redundant CAN communication system, characterized in that, It includes an EtherCAT bus, a CAN bus, and several CAN communication cards. Each CAN communication card has a CAN interface, and the CAN interface of each CAN communication card is connected to the corresponding CAN bus. Each CAN bus can be connected to devices that support the CAN bus protocol. Each CAN communication card includes a communication chip, controller, processor, CAN transceiver, and peripheral interface circuitry. The communication chip is used for data interaction with the controller and the host computer; The controller is used to configure the registers inside the processor, and the controller is also used to monitor the status of the CAN transceiver link inside the processor. The processor is used to interact with the controller, and is also used to receive the controller's configuration results and the monitoring results of the CAN transceiver link status. The processor is also used to expand the CAN interface. The CAN transceiver is used to convert the digital signal output by the processor into a differential signal that can be transmitted on the CAN bus. The peripheral interface circuit is used to realize communication connection with devices that support the CAN bus protocol.
2. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The CAN interfaces of each CAN communication card are redundant.
3. The scalable PLC redundant CAN communication system according to claim 2, characterized in that, The two CAN communication cards are redundant with each other, and each CAN communication card is connected to the same CAN bus through redundant CAN interfaces.
4. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, Each CAN communication card is networked in a ring network configuration.
5. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The communication chip is a communication chip that supports the EtherCAT bus protocol.
6. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The controller is an MCU chip.
7. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The processor is an FPGA chip.
8. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The communication chip is connected to the controller, the controller is connected to the processor, the CAN transceiver is connected to the processor, the peripheral interface circuit is connected to the CAN transceiver, and the peripheral interface circuit is also connected to the communication chip.
9. The scalable PLC redundant CAN communication system according to claim 8, characterized in that, The communication chip is connected to the controller via an SPI interface, the controller is connected to the processor via a QSPI interface, the peripheral interface circuit is connected to the CAN transceiver via a CAN bus, and the peripheral interface circuit is also connected to the communication chip via an RJ45 interface.
10. The scalable PLC redundant CAN communication system according to claim 1, characterized in that, The device that supports the CAN bus protocol is a motor-driven device.