Multi-channel isolation CAN communication test circuit, test system and test method

Abstract

The invention relates to the field of industrial CAN communication circuits, in particular to a multipath isolation CAN communication test circuit, test system and test method, the circuit comprises a plurality of CAN communication units and a synchronous control module, the plurality of CAN communication units are connected with a CAN bus; the synchronous control module comprises multiple paths of microcontrollers and multiple switches, each path of microcontroller is connected with one CAN communication unit, at least one of the multiple switches is connected with the multiple paths of microcontrollers so as to synchronously send CAN messages, and any path of other switches is connected with one microcontroller so as to independently send the CAN messages. Multi-device communication is simulated through the isolated communication nodes controlled by the microcontrollers, communication behaviors can be flexibly configured to reproduce various complex working conditions, the system has the characteristics of low power consumption and serial expansion, the test process can be simplified, the test efficiency can be improved, a real scene can be simulated, and test personnel can be protected; and the cost is low, the operation is simple, automatic testing can be realized, and the reproducibility is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial CAN communication circuit, in particular to a multi-path isolation CAN communication test circuit, a test system and a test method. BACKGROUND

[0002] In the industrial CAN communication scene, the communication demand between multiple devices is very common, and in engineering practice, dozens of devices are often simultaneously accessed and run. In order to ensure system stability, the reliability of system communication must be tested before actual operation. However, when the number of devices to be tested reaches dozens or even hundreds, and the CAN data processing host needs to be tested for reliability, many problems will be encountered. On the one hand, the placement of a large number of devices puts high requirements on the experimental space, which is often difficult to meet; on the other hand, the complexity of operation increases greatly when the experimental personnel manage so many devices for testing, and the probability of error also increases, which directly leads to a significant reduction in work efficiency.

[0003] At the same time, the circuit board to be tested in the industrial environment often involves high-voltage and high-current circuits. In such a test scenario, the personal safety of the tester is at great risk when operating, and it also has an adverse effect on the continuous operation reliability of the test, and this problem is particularly prominent in industrial or other dangerous test scenarios.

[0004] The defects of the prior art mainly include the following points: Firstly, when the number of test devices is large, the demand for experimental space is too large, which is difficult to adapt to the conventional experimental environment, limiting the test conditions.

[0005] Secondly, the management of a large number of devices relies on manual operation, which not only increases the workload of the experimental personnel, but also increases the frequency of operation errors, and seriously reduces the efficiency of the test work.

[0006] Thirdly, for the circuit board to be tested containing high-voltage and high-current circuits, the existing test method cannot effectively protect the safety of the tester, and also affects the continuous stability of the test process, which has great safety hazards and reliability problems.

[0007] Fourthly, there is a lack of special test means to simulate multiple devices concurrently, frequently online and offline, and abnormal data on the CAN bus, which leads to the fact that the reliability test of the CAN data processing host is not comprehensive and accurate enough. SUMMARY

[0008] Therefore, the technical problem to be solved by the present application is the problem of large experimental space demand, easy-to-error manual management, dangerous operation in high-voltage and high-current environment, difficult-to-reproduce complex communication conditions, and low test efficiency in the multi-device scene of industrial CAN communication test.

[0009] To address the aforementioned technical problems, this invention provides a multi-channel isolated CAN communication test circuit, a test system, and a test method. The multi-channel isolated CAN communication test circuit includes: Multiple CAN communication units, wherein the multiple CAN communication units are connected to a CAN bus; The system also includes a synchronization control module, which comprises a multi-channel microcontroller and multiple switches. Each microcontroller is connected to one of the CAN communication units, and at least one of the multiple switches is connected to the multi-channel microcontroller to synchronously send CAN messages. Any of the remaining switches is connected to a microcontroller to independently send CAN messages.

[0010] In one embodiment of the present invention, the CAN communication unit includes a CAN communication chip, a digital isolation chip, a common-mode inductor, a first resistor, and an output interface; The signal terminal of the CAN communication chip is connected to the signal terminal of the digital isolation chip and the microcontroller. The output terminal of the CAN communication chip is connected to the input terminal of the common mode inductor. The first resistor is connected between the output terminals of the common mode inductor and the first resistor is connected to the output interface. The output interface is connected to the CAN bus.

[0011] In one embodiment of the present invention, the CAN communication unit further includes a first filter capacitor, a second filter capacitor, and a third filter capacitor; wherein, one end of the first filter capacitor is connected to the node between the first output terminal of the common mode inductor and the first resistor, and the other end is grounded; one end of the second filter capacitor is connected to the node between the second output terminal of the common mode inductor and the first resistor, and the other end is grounded; one end of the third filter capacitor is connected to the node between the power supply terminal of the CAN communication chip and the isolated power supply module, and the other end is grounded.

[0012] In one embodiment of the present invention, the CAN communication unit further includes an overvoltage protection module, which includes a first diode and a second diode. The positive terminals of the first diode and the second diode are connected in parallel across the two ends of the first resistor, and the negative terminals of both diodes are grounded.

[0013] In one embodiment of the present invention, the overvoltage protection module further includes a second resistor and a third resistor, the second resistor and the third resistor being respectively connected to the two ends of the first resistor, and the other end being connected to the high-level differential signal terminal of the output interface; one end of the second resistor is connected to the low-level differential signal terminal of the output interface.

[0014] In one embodiment of the present invention, the input terminal of the digital isolation chip is connected to the CAN peripheral output terminal of the microcontroller, and the output terminal of the digital isolation chip is connected to the input terminal of the CAN communication chip, so as to transmit the isolated signal to the corresponding CAN communication chip.

[0015] In one embodiment of the present invention, the isolation voltage of the digital isolation chip is not less than 2500Vrms, and the CAN communication chip supports CAN2.0A and CAN2.0B protocols.

[0016] Based on the same inventive concept, the present invention also provides a multi-channel isolated CAN communication test system, which includes the aforementioned test circuit, host computer and CAN data processing host to be tested; The host computer is communicatively connected to the microcontroller; the CAN data processing host is connected to the CAN communication unit of the test circuit via the CAN bus.

[0017] Furthermore, the present invention also provides a multi-channel isolated CAN communication testing method applied to the system, the method comprising the following steps: S1: The host computer sends control commands to a single-channel or multi-channel microcontroller; S2: The microcontroller, according to the control command, drives each CAN communication unit to send analog data to the CAN data processing host while simultaneously acquiring the communication status data of the CAN bus in real time; The simulated data includes normal messages, protocol layer abnormal messages, and priority-differentiated messages. S3: The CAN data processing host acquires and processes the analog data to generate a feedback signal; the CAN communication unit captures the feedback signal in real time through the CAN bus and transmits it to the corresponding microcontroller; the microcontroller uploads the parsed feedback signal to the host computer; at this point, the host computer acquires the operating status data of the CAN data processing host. S4: Based on the operating status data of the CAN data processing host and the communication status data of the CAN bus, the host computer analyzes the communication reliability of the CAN data processing host.

[0018] In one embodiment of the present invention, step S2 further includes: the host computer controls the CAN communication unit of the microcontroller to periodically hibernate or wake up, so as to simulate the dynamic online and offline status of the device.

[0019] The technical solution of the present invention has the following advantages compared with the prior art: This invention employs multiple microcontroller-controlled isolated communication nodes as slave device simulation ends. Each node possesses independent message scheduling and control logic, and its communication behavior can be flexibly configured through preset programs or external interfaces. It can accurately simulate various complex communication conditions such as multi-node concurrent communication, bus arbitration conflicts, mixed asynchronous and periodic message transmission, dynamic node disconnection / online, abnormal message injection, and network load limits. Furthermore, it achieves independent power supply for each CAN chip through isolated power supply to simulate real-world scenarios. It meets different transmission requirements with the help of multi-channel synchronous transmission circuits and supports serial expansion of the number of nodes. This effectively reduces testing costs and cycles, minimizes operational risks, and improves the controllability, reproducibility, safety, and efficiency of testing. It is adaptable to complex testing scenarios and has significant engineering practical value. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a schematic diagram of the module structure of a multi-channel isolated CAN communication test circuit provided in an embodiment of the present invention; Figure 2 This is a circuit connection diagram of a CAN communication unit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a CAN communication testing system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the specific structure of a CAN communication testing system provided in an embodiment of the present invention; Figure 5 This is a flowchart illustrating a multi-channel isolated CAN communication testing method provided in an embodiment of the present invention; Explanation of reference numerals in the accompanying drawings: 1. CAN communication unit; 2. Synchronization control module; 21. Microcontroller; 22. Switch;

[0021] 100. Host computer; 200. Test circuit; 300. CAN data processing host. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0023] Example 1: like Figure 1 As shown, this invention provides a multi-channel isolated CAN communication test circuit, comprising: multiple CAN communication units 1 and a synchronization control module 2; wherein, The plurality of CAN communication units 1 are connected to the CAN bus; The synchronization control module 2 includes a multi-channel microcontroller 21 and a plurality of switches 22. Each microcontroller 1 is connected to one of the CAN communication units 1, and at least one of the plurality of switches 22 is connected to the multi-channel microcontroller 21 to synchronously send CAN messages. Any of the remaining switches 22 is connected to a microcontroller 21 to independently send CAN messages.

[0024] Furthermore, in this embodiment, as Figure 2 As shown, the CAN communication unit 1 includes a CAN communication chip U5, a digital isolation chip U6, a common-mode inductor L1, a first resistor R1, and an output interface containing CAN_H and CAN_L differential signal lines; The serial communication interface (TXD_1, RXD_1) of the CAN communication chip U5 is connected to the signal terminal of the microcontroller 21 through the digital isolation chip U6 (INA pin and OUTB pin). The digital isolation chip U6 provides signal ground reference isolation on this critical path, effectively blocking the ground loop current between the microcontroller 21 and the CAN bus, significantly improving the system's common-mode interference immunity, enhancing electrical safety, and suppressing the risk of communication errors or equipment damage caused by potential ground potential differences.

[0025] The output terminals (CANH, CANL) of the CAN communication chip U5 are connected to the input terminals (pins 1 and 2) of the common-mode inductor L1. This direct drive connection ensures the strong driving capability and fast edge rate control of the CAN communication chip U5 for bus signals. The common-mode inductor L1 is connected in series in the signal transmission path. Utilizing its high common-mode impedance characteristics, it efficiently filters out common-mode noise superimposed on the CAN_H and CAN_L differential signal lines, significantly reducing the sensitivity to electromagnetic interference (EMI) transmission and reception, and improving the robustness of bus communication in harsh electromagnetic environments.

[0026] The first output terminal (pin 4) of the common-mode inductor L1 is connected to the CAN_H high-level differential signal port of the output interface, and its second output terminal (pin 3) is connected to the CAN_L low-level differential signal port of the output interface. Both the CAN_H high-level differential signal port and the CAN_L low-level differential signal port are connected to the target CAN bus network. The first resistor R1 is connected between the output terminal of the common-mode inductor L1 and the output interface, providing precise characteristic impedance matching for the CAN bus. This minimizes signal reflection at the end of the bus cable, ensuring signal waveform integrity and reducing the bit error rate (BER), which is crucial for ensuring the reliability of high-speed CAN communication and long-distance transmission capability.

[0027] In this embodiment, the input terminal of the digital isolation chip U6 is connected to the CAN peripheral output terminal of the microcontroller 21, and the output terminal of the digital isolation chip U6 is connected to the input terminal of the CAN communication chip U5, so as to transmit the isolated signal to the corresponding CAN communication chip U5. Preferably, the isolation voltage of the digital isolation chip U6 is not less than 2500Vrms, and the CAN communication chip U5 supports CAN2.0A and CAN2.0B protocols.

[0028] Furthermore, the CAN communication unit 1 also includes a first filter capacitor C1, a second filter capacitor C2, and a third filter capacitor C3.

[0029] In this design, one end of the first filter capacitor C1 is connected to the connection node between the first output terminal of the common-mode inductor L1 and the first resistor R1, while the other end is grounded. The first filter capacitor C1 and the choke coil form a π-type filter network, providing a low-impedance discharge path for high-frequency common-mode noise. Its capacitance design (typical value 1-10nF) can effectively filter out common-mode interference >30MHz, significantly reducing bus radiated electromagnetic interference (RE) and conducted emissions (CE), and improving system EMC compliance.

[0030] The second filter capacitor C2 is symmetrically positioned between the connection point of the second output terminal of the common-mode inductor L1 and the first resistor R1, and ground GND. The second filter capacitor C2 and the first filter capacitor C1 form a completely symmetrical filter structure, ensuring balanced impedance to ground for the CAN_H / CAN_L signal lines. This design suppresses common-mode to differential-mode noise conversion caused by line asymmetry, avoids signal eye diagram distortion, maintains differential signal integrity (SI), and enhances electrostatic discharge (ESD) immunity.

[0031] The third filter capacitor C3 serves as a local high-frequency decoupling unit. One end is connected to the connection node between the power input pin VCC of the CAN communication chip U5 and the isolation power output terminal of the isolation power module U6, while the other end is grounded. The extremely low ESL (equivalent series inductance) characteristic of the third filter capacitor C3 can absorb the switching noise (>10MHz) of the isolation power module and the transceiver burst current. This design significantly improves the transient response of the power supply voltage (ΔV / Δt), suppresses the power rail ripple to <50mV, and prevents transceiver false triggering or communication errors caused by power supply noise.

[0032] Specifically, the CAN communication unit 1 further includes an overvoltage protection module, which includes a first diode D1, a second diode D2, a second resistor R2, and a third resistor R3. The first diode D1 and the second diode D2 are both TVS diodes, and their positive terminals are connected in parallel across the first resistor R1, while their negative terminals are grounded. This enables nanosecond-level response clamping of the differential-mode surge voltage between CAN_H and CAN_L to a safe threshold, and absorbs up to 1500W peak pulse power (10 / 1000μs waveform), effectively protecting against electrostatic discharge (ESD>±15kV) and transient high-voltage surges caused by switching on and off inductive loads; maintaining voltage compatibility of the bus differential signal during faults, and preventing the CAN communication chip U5 from being damaged.

[0033] Furthermore, the second resistor R2 serves as an impedance matching resistor with a value of 0-22Ω. It is connected in series between the first output terminal of the common-mode inductor L1 and the CAN_H of the output interface to suppress signal reflection and optimize the rising edge of the bus signal; it also limits the high-voltage inrush current flowing to the bus when the second diode D2 operates and provides primary current isolation under short-circuit fault conditions, meeting the fault protection requirements of ISO11898-2.

[0034] The third resistor R3 and the second resistor R2 form a completely symmetrical current limiting network, which is connected in series between the second output terminal of the common mode inductor L1 and the CAN_L of the output interface. This ensures the impedance balance of the CAN_H / CAN_L lines, blocks the interference of ground loop current on the differential signal, improves the common mode rejection ratio, and works with the first diode D1 to form a two-stage protection of "current limiting-clamping".

[0035] Example 2:

[0036] Based on the same inventive concept as Embodiment 1, the present invention also provides a multi-channel isolated CAN communication test system, such as... Figure 3 and Figure 4 As shown, the system includes a host computer 100, a test circuit 200 as described in Embodiment 1, and a CAN data processing host 300 to be tested. The host computer 100 is communicatively connected to the microcontroller 21. The CAN data processing host is connected to the CAN communication unit 1 of the test circuit 200 via a CAN bus.

[0037] The host computer 100 transmits test configuration instructions (such as "start 10 nodes to send normal messages synchronously + 2 nodes to send frame error messages") to the microcontroller 21 of the test circuit 200 through a serial communication interface (such as UART, USB, Ethernet). After parsing the instructions, the microcontroller 21 controls the corresponding CAN communication unit 1 to enter the preset working mode.

[0038] The CAN communication unit 1 generates simulated data (including normal / abnormal messages) conforming to the CAN 2.0A / B protocol according to the control logic of the microcontroller 21, and transmits it to the CAN interface of the CAN data processing host 300 through the CAN bus (CAN_H / CAN_L differential signals) to simulate the communication process between multiple devices and the CAN data processing host 300 in an industrial scenario.

[0039] After processing the analog data, the CAN data processing host 300 sends feedback signals (such as ACK confirmation for normal messages and error frame response for abnormal messages) through the CAN bus; the host computer 100 reads the internal status of the CAN data processing host 300 (such as data reception success rate and buffer occupancy rate) through the CAN communication unit 1 for reliability analysis.

[0040] In summary, through its layered architecture design, this system enables programmable construction of test scenarios, unmanned execution of the test process, and visualized analysis of test results, effectively improving the test coverage and verification efficiency of industrial CAN communication equipment. It is particularly suitable for the development and reliability verification stages of CAN bus systems in fields such as automotive electronics and industrial automation.

[0041] Example 3: like Figure 5 As shown, the present invention also provides a multi-channel isolated CAN communication testing method applied to the system described in Embodiment 2, the method comprising the following steps: S1: Before conducting the test, the user sets the test parameters through the visual interface of the host computer 100 (such as "simulating 20 devices communicating concurrently, of which 5 devices periodically go online and offline, and injecting 10% frame error messages"). The host computer 100 encapsulates the configuration parameters into control instructions. Subsequently, the host computer 100 sends control commands to the single-channel or multi-channel microcontroller 21, and the microcontroller 21 initializes the working parameters of each CAN communication unit 1 (such as message ID, transmission period, error injection rules). The control commands include, but are not limited to, parameters such as the number of CAN communication units 1 enabled, message transmission mode (single-channel independent transmission / multi-channel synchronous transmission), and operating condition triggering conditions (such as concurrent cycle and abnormal injection time). S2: After receiving the control command from the host computer 100, the microcontroller 21 generates a corresponding control signal through internal logic parsing. Then, based on the parsed control command, it drives each CAN communication unit 1 to acquire the communication status data of the CAN bus (such as transmission success rate and bus load) in real time while sending analog data. The analog data includes: Normal message: Standard or extended frames conforming to the CAN 2.0A / B protocol specification, used to simulate routine data reporting by the device; Protocol layer error messages include frame errors (such as CRC check failure, missing ACK), bit errors (single bit flip, stuffing error), illegal IDs (identifiers outside the range specified by the protocol), etc., and are used to verify the fault tolerance mechanism of the test object. Priority-differentiated messages: Configure message sequences with different ID priorities to simulate bus arbitration conflict scenarios; S3: After processing the simulated data, the CAN data processing host 300 generates a feedback signal. The CAN communication unit 1 of the test circuit 200 captures the feedback signal in real time through the CAN bus and transmits it to the microcontroller 21. The microcontroller 21 parses the feedback signal and uploads the parsed result to the host computer 100. Thus, the host computer 100 obtains the operating status data of the CAN data processing host 300 (such as data reception completion rate and error handling response time). S4: After the test, the host computer 100 automatically generates a test report based on the operating status data of the CAN data processing host 300 and the communication status data of the CAN bus, by comparing with preset standards (such as "the success rate of normal message reception should be ≥99.9%), and determines whether the communication reliability of the CAN data processing host 300 meets the standard.

[0042] Furthermore, in this embodiment, step S2 also includes: the host computer 100 controls part of the CAN communication unit 1 to periodically sleep (cut off transmission enable or reduce power consumption) or wake up (restore transmission logic) state through the microcontroller 21, accurately simulating the dynamic disconnection / online process of equipment caused by power supply fluctuations, interference, etc. in the industrial environment, and this operation is realized through isolated power supply and software control to avoid physical damage to hardware and ensure the repeatability and safety of the test.

[0043] The above method, through standardized process design, enables the controllable reproduction of complex communication conditions. Compared with traditional testing methods that rely on real equipment, it significantly improves testing efficiency and scenario coverage, and is especially suitable for the development and verification stage of CAN bus systems in fields such as industrial control and automotive electronics.

[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multi-channel isolated CAN communication test circuit, characterized in that, include: Multiple CAN communication units, wherein the multiple CAN communication units are connected to a CAN bus; The system also includes a synchronization control module, which comprises a multi-channel microcontroller and multiple switches. Each microcontroller is connected to one of the CAN communication units, and at least one of the multiple switches is connected to the multi-channel microcontroller to synchronously send CAN messages. Any of the remaining switches is connected to a microcontroller to independently send CAN messages.

2. The multi-channel isolated CAN communication test circuit according to claim 1, characterized in that, The CAN communication unit includes a CAN communication chip, a digital isolation chip, a common-mode inductor, a first resistor, and an output interface; The signal terminal of the CAN communication chip is connected to the signal terminal of the digital isolation chip and the microcontroller. The output terminal of the CAN communication chip is connected to the input terminal of the common mode inductor. The first resistor is connected between the output terminals of the common mode inductor and the first resistor is connected to the output interface. The output interface is connected to the CAN bus.

3. The multi-channel isolated CAN communication test circuit according to claim 2, characterized in that, The CAN communication unit further includes a first filter capacitor, a second filter capacitor, and a third filter capacitor; wherein, one end of the first filter capacitor is connected to the node between the first output terminal of the common mode inductor and the first resistor, and the other end is grounded; one end of the second filter capacitor is connected to the node between the second output terminal of the common mode inductor and the first resistor, and the other end is grounded; one end of the third filter capacitor is connected to the node between the power supply terminal of the CAN communication chip and the isolated power supply module, and the other end is grounded.

4. The multi-channel isolated CAN communication test circuit according to claim 2, characterized in that, The CAN communication unit also includes an overvoltage protection module, which includes a first diode and a second diode. The positive terminals of the first diode and the second diode are connected in parallel across the two ends of the first resistor, and the negative terminals of both diodes are grounded.

5. The multi-channel isolated CAN communication test circuit according to claim 4, characterized in that, The overvoltage protection module further includes a second resistor and a third resistor. The second resistor and the third resistor are respectively connected to the two ends of the first resistor, and the other end is connected to the high-level differential signal terminal of the output interface; one end of the second resistor is connected to the low-level differential signal terminal of the output interface.

6. The multi-channel isolated CAN communication test circuit according to claim 2, characterized in that, The input terminal of the digital isolation chip is connected to the CAN peripheral output terminal of the microcontroller, and the output terminal of the digital isolation chip is connected to the input terminal of the CAN communication chip, so as to transmit the isolated signal to the corresponding CAN communication chip.

7. The multi-channel isolated CAN communication test circuit according to claim 2, characterized in that, The isolation voltage of the digital isolation chip is not less than 2500Vrms, and the CAN communication chip supports CAN2.0A and CAN2.0B protocols.

8. A multi-channel isolated CAN communication test system, characterized in that, Includes the test circuit, host computer, and CAN data processing host to be tested as described in any one of claims 1 to 7; The host computer is communicatively connected to the plurality of microcontrollers; the CAN data processing host is connected to the CAN communication unit of the test circuit via a CAN bus.

9. A method for testing multi-channel isolated CAN communication applied to the system as described in claim 8, characterized in that, Includes the following steps: S1: The host computer sends control commands to a single-channel or multi-channel microcontroller; S2: The microcontroller, according to the control command, drives each CAN communication unit to send analog data to the CAN data processing host while simultaneously acquiring the communication status data of the CAN bus in real time; The simulated data includes normal messages, protocol layer abnormal messages, and priority-differentiated messages. S3: The CAN data processing host acquires and processes the analog data to generate a feedback signal; the CAN communication unit captures the feedback signal in real time through the CAN bus and transmits it to the corresponding microcontroller; the microcontroller uploads the parsed feedback signal to the host computer; at this point, the host computer acquires the operating status data of the CAN data processing host. S4: Based on the operating status data of the CAN data processing host and the communication status data of the CAN bus, the host computer analyzes the communication reliability of the CAN data processing host.

10. The test method according to claim 9, characterized in that, Step S2 further includes: the host computer controls the CAN communication unit of the microcontroller to periodically sleep or wake up, so as to simulate the dynamic online and offline status of the device.

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