Lossless wire-breaking-free automobile CAN bus testing device

Abstract

The invention discloses a lossless and line-breaking-free automobile CAN bus testing device, and the device is characterized in that an induction signal interface is connected with a conductive clamp, and is used for obtaining a surface induction signal of a CAN signal line; the CAN signal extraction module is connected with the induction signal interface and is used for converting a surface induction signal of a CAN signal line into a logic signal; the CAN signal conversion module is connected with the CAN signal extraction module, the main control module and the CAN signal interface and used for converting logic signals from the CAN signal extraction module or the main control module into CAN signals and sending the CAN signals to the CAN signal interface and converting the CAN signals received from the CAN signal interface into logic signals and sending the logic signals to the main control module, and the display module is connected with the main control module. And the display module is used for displaying CAN signal identification data information. By using the method and the device, a user can conveniently obtain the CAN bus signal without damaging a CAN communication line or additionally arranging a terminal in the automobile maintenance process, so that the maintenance efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the field of automobile equipment detection, and in particular relates to a non-destructive and non-breaking automobile CAN bus test device. Background Art

[0002] In the process of repairing automotive electrical modules, it is often encountered that the communication line voltage is normal but communication is not possible. The traditional solution requires the use of a CAN analyzer connected to computer software to check the communication data, which has relatively high requirements on the user's professional ability level, and the number of detection and maintenance equipment is large, the site space is large, the connection layout operation is cumbersome, and it is inconvenient to carry and carry.

[0003] Chinese patent CN202322788969.7 proposes a test device for detecting the performance of vehicle CAN serial port and LIN serial port, which can be connected to the communication interface through a probe, and the data communication of CAN signal or LIN signal can be observed through the display window of the device. When the device is used to collect CAN signals, it is necessary to directly access the communication medium of the CAN signal through the probe, that is, the CAN signal can only be collected by directly connecting the CAN signal socket or cutting the CAN signal line, which will bring inconvenience to maintenance and even cause damage to the equipment.

[0004] In view of this, it is necessary to propose a new device to solve the above problems. Summary of the invention

[0005] In order to solve the common problems in the prior art, the present invention proposes an embodiment of an automobile communication bus testing device with wireless signal display. When detecting the automobile CAN bus communication signal, damage to the CAN communication line can be avoided. The CAN bus communication signal is obtained from the surface of the CAN signal line through a conductive clip, which is convenient for users to use.

[0006] The technical solution adopted by the present invention is:

[0007] A lossless and line-breaking-free automobile CAN bus test device comprises: an induction signal interface, a CAN signal interface, a CAN signal extraction module, a CAN signal conversion module, a main control module, a display module and a power module; the induction signal interface is connected to a conductive clip for obtaining a surface induction signal of a CAN signal line; the CAN signal extraction module is connected to the induction signal interface for converting a surface induction signal of the CAN signal line into a logic signal; the CAN signal conversion module is connected to the CAN signal extraction module, the main control module and the CAN signal interface for converting a logic signal from a CAN signal extraction module or a main control module into a CAN signal and sending it to the CAN signal interface, and for converting a CAN signal received from the CAN signal interface into a logic signal and sending it to the main control module; the display module is connected to the main control module for displaying CAN signal identification data information; the power module is used to provide an adaptive power supply for the device.

[0008] Furthermore, the conductive clip includes a conductive contact piece, which is arranged at a clamping portion of the conductive clip, and the conductive contact piece is connected to the induction signal interface through a wire.

[0009] Furthermore, it also includes a polarity switching module, which is connected between the sensing signal interface and the CAN signal extraction module and is used to switch the polarity of the connection between the sensing signal interface and the CAN signal extraction module according to the control of the main control module.

[0010] Furthermore, the polarity switching module includes a relay K1 and a switch tube Q5, the first normally open end and the second normally closed end of the relay K1 are connected to the positive end of the sensing signal interface, the second normally open end and the first normally closed end of the relay K1 are connected to the negative end of the sensing signal interface, the first common end of the relay K1 is connected to the CAN sensing low signal end, the second common end of the relay K1 is connected to the CAN sensing high signal end, and the signal polarity control end of the main control module controls the coil of the relay K1 to be energized or de-energized through the switch tube Q5.

[0011] Further, the CAN signal extraction module includes a first comparator, a second comparator, an AND logic operation unit, and an OR logic operation unit; the positive input end of the first comparator is connected to the CAN sensing high signal end, and the negative input end is connected to the CAN sensing low signal end, the CAN sensing high signal end is connected to the negative input end of the second comparator after voltage division by resistors R12 and R17, the CAN sensing low signal end is connected to the CAN signal extraction module power supply through resistors R13 and R21, and the connection point between resistors R13 and R21 is also connected to the positive input end of the second comparator; the output end of the second comparator is connected to an input end of the OR logic operation unit, the other input end of the OR logic operation unit is grounded, the output end of the OR logic operation unit is connected to an input end of the AND logic operation unit, the other input end of the AND logic operation unit is connected to the output end of the first comparator, and the output end of the AND logic operation unit is connected to the output end of the OR logic operation unit and serves as the output end of the CAN signal extraction module.

[0012] Furthermore, the CAN signal conversion module includes a CAN signal conversion chip U2 and a CAN signal conversion chip U4, the CANH and CANL pins of the CAN signal conversion chip U2 and the CAN signal conversion chip U4 are both connected to the CAN signal interface, the TXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal sending end of the main control module, the RXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal receiving end of the main control module, and the TXD pin of the CAN signal conversion chip U2 is connected to the output end of the CAN signal extraction module.

[0013] Further, the power module includes a battery, a switch tube Q1, a switch tube Q2, a two-terminal diode D4, a power switch, a resistor R9, a resistor R16, a capacitor C9, a first voltage conversion unit and a second voltage conversion unit; the positive electrode of the battery is connected to the source of the switch tube Q1, the gate of the switch tube Q1 is connected to the drain of the switch tube Q2, the source of the switch tube Q2 is grounded, the gate of the switch tube Q2 is connected to the power control end of the main control module, the resistor R16 is connected in parallel between the gate and source of the switch tube Q2; the resistor R9 is connected in parallel between the gate and source of the switch tube Q1, and the The gate of the switch tube Q1 is also connected to an anode of the two-terminal diode D4, the cathode of the diode D4 is grounded through the power switch, the other anode of the two-terminal diode D4 is connected to the switch detection end of the main control module and one end of the capacitor C9, and the other end of the capacitor C9 is grounded; the drain of the switch tube Q1 is connected to the input end of the first voltage conversion unit, and the output end of the first voltage conversion unit is connected to the input end of the second voltage conversion unit; the first voltage conversion unit is used to convert the battery output voltage into a 5V voltage, and the second voltage conversion unit is used to convert the 5V voltage into a 3.3V voltage.

[0014] Furthermore, the display module includes an OLED display screen.

[0015] Furthermore, it also includes a shell, the sensing signal interface, CAN signal interface and OLED display screen are all arranged on the surface of the shell, and parts of the CAN signal extraction module, CAN signal conversion module, main control module and power supply module are all arranged on a circuit board embedded in the shell.

[0016] The beneficial effects of the present invention are:

[0017] The present invention proposes a non-destructive and non-breaking automobile CAN bus test device. The user clamps the conductive clip on the surface of the automobile CAN signal line. When there is a communication signal in the CAN signal line, the conductive clip on the surface of the CAN signal line generates an induction signal, which is connected to the device through the induction signal interface. The CAN signal extraction module converts the induction signal on the surface of the CAN signal line into a logic signal. On the one hand, the logic signal is output to the main control module and displayed by the display module; on the other hand, the logic signal is output to the CAN signal conversion module, converted into a CAN signal in the form of a differential signal that can be transmitted on the CAN bus, and then output through the CAN signal interface. In some applications, other CAN signal analysis devices can be connected to the CAN signal interface to analyze the non-destructively acquired CAN signal. In some applications, the user can also directly obtain the differential CAN signal from the CAN signal interface, and after the CAN signal conversion module converts it into a logic signal, it is output to the main control module and displayed by the display module. By using the embodiment of the present invention, the user can easily obtain the CAN bus signal during automobile maintenance without destroying the CAN communication line or setting up a separate terminal, which can improve the maintenance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an electrical principle block diagram of an embodiment of a lossless and wire-breaking-free automobile CAN bus test device of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of an embodiment of a lossless and wire-breaking-free automobile CAN bus test device of the present invention;

[0020] Figure 3 This is another electrical principle block diagram of a non-destructive and non-breaking-wire automobile CAN bus test device embodiment of the present invention;

[0021] Figure 4 This is the circuit schematic diagram of the polarity switching module;

[0022] Figure 5 This is the circuit schematic diagram of the CAN signal extraction module;

[0023] Figure 6 This is the electrical principle block diagram of the CAN signal conversion module;

[0024] Figure 7 This is the electrical principle block diagram of the power module.

[0025] In the figure:

[0026] 100-housing, 200-sensing signal interface, 210-conductive clip, 220-wire, 300-CAN signal interface, 400-CAN signal extraction module, 500-CAN signal conversion module, 600-main control module, 700-display module, 800-power module, 810-button, 900-polarity switching module. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] The terms "first", "second" and "third" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of the indicated technical features. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative position relationship or movement between the components in a certain specific posture (as shown in the accompanying drawings); it should be noted that when a component is referred to as "fixed to", "set to", or "connected to" another component, it can be directly on the other component or there can be a central component. When a component is considered to be "connected" to another component, it can be directly connected to another component, or there may be one or more central components in between. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0029] like Figure 1 to Figure 7 As shown, in order to solve the common problems in the prior art, the present invention proposes an embodiment of a non-destructive and non-breakage automobile CAN bus testing device, which can avoid damage to the CAN communication line when detecting the automobile CAN bus communication signal, and obtain the CAN bus communication signal from the surface of the CAN signal line through a conductive clip, which is convenient for users to use.

[0030] Specifically, see Figure 1 and Figure 2A non-destructive and non-breaking automobile CAN bus test device comprises: an induction signal interface 200, a CAN signal interface 300, a CAN signal extraction module 400, a CAN signal conversion module 500, a main control module 600, a display module 700 and a power module 800; the induction signal interface 200 is connected to a conductive clip 210 for obtaining a surface induction signal of a CAN signal line; the CAN signal extraction module 400 is connected to the induction signal interface 200 for converting a surface induction signal of the CAN signal line into a logic signal; the CAN signal conversion module 500 is connected to the CAN signal extraction module 400, the main control module 600 and the CAN signal interface 300 for converting a logic signal from the CAN signal extraction module 400 or the main control module 600 into a CAN signal and sending it to the CAN signal interface 300, and for converting a CAN signal received from the CAN signal interface 300 into a logic signal and sending it to the main control module 600; the display module 700 is connected to the main control module 600 for displaying CAN signal identification data information; the power module 800 is used to provide an adaptive power supply for the device.

[0031] The working principle of the embodiment of the present invention is:

[0032] The user clamps the conductive clip 210 on the surface of the CAN signal line of the car. When there is a communication signal in the CAN signal line, the conductive clip 210 on the surface of the CAN signal line generates an induction signal, which is connected to the device through the induction signal interface 200. The CAN signal extraction module 400 converts the induction signal on the surface of the CAN signal line into a logic signal. On the one hand, the logic signal is output to the main control module and displayed by the display module 700; on the other hand, the logic signal is output to the CAN signal conversion module 500, converted into a CAN signal in the form of a differential signal that can be transmitted on the CAN bus, and then output through the CAN signal interface 300. In some applications, other CAN signal analysis equipment can be connected to the CAN signal interface 300 to analyze the CAN signal obtained losslessly. In some applications, the user can also directly obtain the CAN signal in the form of a differential CAN signal from the CAN signal interface 300, and after being converted into a logic signal by the CAN signal conversion module 500, it is output to the main control module and displayed by the display module 700.

[0033] By using the embodiment of the present invention, a user can conveniently obtain a CAN bus signal during automobile maintenance without damaging the CAN communication line or setting up an additional terminal, thereby improving maintenance efficiency.

[0034] It should be noted that, in a specific implementation, the main control module 600 may be a microprocessor, for example, model APM32F072.

[0035] In some embodiments, the conductive clip 210 includes a conductive contact, which is disposed at a clamping portion of the conductive clip, and is connected to the inductive signal interface 200 via a wire 220. When the conductive clip 210 is clamped on the surface of the CAN signal line, the conductive contact contacts the surface of the CAN signal line. When there is a communication signal in the CAN signal line, an inductive signal is generated at the conductive contact of the conductive clip 210 and is transferred to the inductive signal interface 200 via the wire 220.

[0036] In some embodiments, see Figure 3 A non-destructive and non-breaking automobile CAN bus test device also includes a polarity switching module 900, which is connected between the sensing signal interface 200 and the CAN signal extraction module 400, and is used to switch the polarity of the connection between the sensing signal interface 200 and the CAN signal extraction module 400 according to the control of the main control module 600. When using, the user can obtain the CAN signal without deliberately adjusting the polarity of the conductive clip 210 connected to the CAN signal line.

[0037] In some embodiments, see Figure 4 The polarity switching module 900 includes a relay K1, a diode D8, a switch tube Q5 and a resistor R14. The first normally open terminal NO1 and the second normally closed terminal NC2 of the relay K1 are connected to the positive terminal P+ of the sensing signal interface, the second normally open terminal NO2 and the first normally closed terminal NC1 of the relay K1 are connected to the negative terminal P- of the sensing signal interface, the first common terminal COM1 of the relay K1 is connected to the CAN sensing low signal terminal CANL, the second common terminal COM2 of the relay K1 is connected to the CAN sensing high signal terminal CANH, and the signal polarity control terminal CANHL of the main control module controls the coil of the relay K1 to be energized or de-energized through the switch tube Q5.

[0038] In a specific implementation, the switch tube Q5 is an NMOS tube, the gate of the switch tube Q5 is connected to the signal polarity control terminal CANHL of the main control module 600, the source of the switch tube Q5 is grounded, the resistor R14 is connected between the gate and the source, the coil of the relay K1 is connected between the drain and the 5V power supply VCC-5V, the cathode of the diode D8 is connected to the 5V power supply VCC-5V, and the anode is connected to the drain of the switch tube Q5.

[0039] The main control module 600 switches the polarity of the connection between the sensing signal interface 200 and the CAN signal extraction module 400 by controlling the level of the signal polarity control terminal CANHL. When the signal polarity control terminal CANHL is at a high level, the coil of the relay K1 is energized, the first common terminal COM1 is connected to the first normally open terminal NO1, and the second common terminal COM2 is connected to the second normally open terminal NO2. At this time, the positive terminal P+ of the sensing signal interface 400 is connected to the CAN sensing low signal terminal CANL, and the negative terminal P- of the sensing signal interface 400 is connected to the CAN sensing high signal terminal CANH. When the signal polarity control terminal CANHL is at a low level, the coil of the relay K1 is de-energized, the first common terminal COM1 is connected to the first normally closed terminal NC1, and the second common terminal COM2 is connected to the second normally closed terminal NC2. At this time, the positive terminal P+ of the sensing signal interface 400 is connected to the CAN sensing high signal terminal CANH, and the negative terminal P- of the sensing signal interface 400 is connected to the CAN sensing low signal terminal CANL. After the device is powered on, the signal polarity control terminal CANHL controls the relay K1 to continuously switch its state until the main control module 600 receives the CAN signal, and then the state of the relay K1 is fixed and no longer switched.

[0040] In some embodiments, see Figure 5 The CAN signal extraction module 400 includes a first comparator U6A, a second comparator U6B, an AND logic operation unit U9, an OR logic operation unit U10, a resistor R12, a resistor R17, a resistor R13 and a resistor R21; the positive input end of the first comparator U6A is connected to the CAN sensing high signal end CANH, and the negative input end is connected to the CAN sensing low signal end CANL. The CAN sensing high signal end CANH is connected to the negative input end of the second comparator U6B after voltage division by the resistor R12 and the resistor R17, and the CAN sensing low signal end CANL is connected to the CAN signal extraction The module power supply is VCC-5VA, and the connection point of the resistor R13 and the resistor R21 is also connected to the positive input terminal of the second comparator U6B; the output terminal of the second comparator U6B is connected to an input terminal of the OR-NO logic operation unit U10, and the other input terminal of the OR-NO logic operation unit U10 is grounded, and the output terminal of the OR-NO logic operation unit U10 is connected to an input terminal of the logic operation unit U9, and the other input terminal of the logic operation unit U9 is connected to the output terminal of the first comparator U6A, and the output terminal of the logic operation unit U9 is connected to the output terminal of the OR-NO logic operation unit U10 and serves as the output terminal TC of the CAN signal extraction module.

[0041] In the specific implementation, the transmission standard of the CAN bus is divided into high-speed and low-speed fault tolerance, and the data state includes dominant state and recessive state. According to the voltage of the high end of the CAN bus signal and the high end of the signal in different states, the output terminal TC of the CAN signal extraction module 400 outputs a high level or low level logic signal.

[0042] For example, when the transmission standard of the CAN bus is high speed and the data state is dominant, the high-end voltage of the signal is approximately 3.5V and the low-end voltage of the signal is approximately 1.5V; when the transmission standard of the CAN bus is low-speed fault tolerance and the data state is dominant, the high-end voltage of the signal is approximately 4V and the low-end voltage of the signal is approximately 1V; in these two cases, by setting multiple resistance values ​​in the CAN signal extraction module, the positive input terminal level of the second comparator U6B can be made lower than the negative input terminal level, and the second comparator U6B will output a low level, or the non-logical operation unit U10 will output a high level, so that the output terminal TC of the CAN signal extraction module outputs a high level. The transmission standard of the CAN bus is high speed. When the data state is recessive, the high-end voltage and the low-end voltage of the signal are both close to 2.5V; the transmission standard of the CAN bus is low-speed fault tolerance. When the data state is recessive, the high-end voltage of the signal is about 1.75V and the low-end voltage of the signal is about 3.25V; in these two cases, the setting of multiple resistance values ​​in the aforementioned CAN signal extraction module can also make the positive input terminal level of the second comparator U6B higher than the negative input terminal level, and the second comparator U6B will output a high level, or the non-logic operation unit U10 will output a low level, so that the output terminal TC of the CAN signal extraction module 400 outputs a low level. Other resistors and capacitors play a role in signal conditioning and filtering, which will not be repeated here.

[0043] In some embodiments, see Figure 6 The CAN signal conversion module 500 includes a CAN signal conversion chip U2 and a CAN signal conversion chip U4. The CANH and CANL pins of the CAN signal conversion chip U2 and the CAN signal conversion chip U4 are both connected to the CAN signal interface. The TXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal sending end CAN_TXD of the main control module. The RXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal receiving end CAN_RXD of the main control module. The TXD pin of the CAN signal conversion chip U2 is connected to the output end TC of the CAN signal extraction module 400.

[0044] In a specific implementation, the logic signal obtained by the CAN signal extraction module 400 is converted into a differential CAN signal using the CAN signal conversion chip U4. The logic signal sent by the main control module 600 is converted into a differential CAN signal using the CAN signal conversion chip U2 and sent to the CAN signal interface 300. The differential CAN signal received by the CAN signal interface 300 is converted into a logic signal using the signal conversion chip U2 and sent to the main control module 600.

[0045] In some embodiments, see Figure 7The power module 800 includes a battery, a switch tube Q1, a switch tube Q2, a two-terminal diode D4, a power switch KEY1, a resistor R9, a resistor R16, a capacitor C9, a first voltage conversion unit and a second voltage conversion unit; the positive electrode of the battery is connected to the source of the switch tube Q1, the gate of the switch tube Q1 is connected to the drain of the switch tube Q2, the source of the switch tube Q2 is grounded, the gate of the switch tube Q2 is connected to the power control terminal POW_EN of the main control module, the resistor R16 is connected in parallel between the gate and the source of the switch tube Q2; the resistor R9 is connected in parallel between the gate and the source of the switch tube Q1 The gate of the switch tube Q1 is also connected to an anode of a two-terminal diode D4, the cathode of the diode D4 is grounded through the power switch KEY1, the other anode of the two-terminal diode D4 is connected to the switch detection terminal SW of the main control module and one end of the capacitor C9, and the other end of the capacitor C9 is grounded; the drain of the switch tube Q1 is connected to the input end of the first voltage conversion unit, and the output end of the first voltage conversion unit is connected to the input end of the second voltage conversion unit; the first voltage conversion unit is used to convert the battery output voltage into a 5V voltage, and the second voltage conversion unit is used to convert the 5V voltage into a 3.3V voltage. The switch tube Q1 is a PMOS tube, and the switch tube Q2 is an NMOS tube.

[0046] In a specific implementation, the power switch KEY1 is turned on by the button 810. When the user long presses the button 810, the power switch KEY1 is turned on, the source of the switch tube Q1 is grounded through the two-terminal diode D4 and the power switch KEY1, the switch tube Q1 is saturated and turned on, and the battery supplies power to the device through the fuse F1. After that, the power control terminal POW_EN of the main control module 600 is high, so that the switch tube Q2 is saturated and turned on, thereby maintaining the conduction state of the switch tube Q1. When the user long presses the button 810 again, the power switch KEY1 is turned on, and the switch detection terminal SW of the main control module 600 will be set to a low level. After that, the power control terminal POW_EN of the device main control module 600 is low, so that the switch tube Q2 is turned off. After the user releases the button 810, the switch tube Q1 will be turned off to achieve shutdown and power off.

[0047] In some embodiments, see Figure 2 , the display module 700 includes an OLED display screen 710 .

[0048] In some embodiments, see Figure 2 , also includes a shell 100, a sensing signal interface 200, a CAN signal interface 300, an OLED display screen 710 and a button 810 are all arranged on the surface of the shell 100, and parts of the CAN signal extraction module 400, the CAN signal conversion module 500, the main control module 600 and the power supply module 800 are all arranged on a circuit board embedded in the shell 100.

[0049] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A non-destructive and non-breaking automobile CAN bus test device, characterized in that: include: An induction signal interface, a CAN signal interface, a CAN signal extraction module, a CAN signal conversion module, a main control module, a display module and a power supply module; the induction signal interface is connected to a conductive clip for obtaining a surface induction signal of a CAN signal line; the CAN signal extraction module is connected to the induction signal interface for converting a surface induction signal of a CAN signal line into a logic signal; the CAN signal conversion module is connected to the CAN signal extraction module, the main control module and the CAN signal interface for converting a logic signal from a CAN signal extraction module or a main control module into a CAN signal and sending it to the CAN signal interface, and for converting a CAN signal received from the CAN signal interface into a logic signal and sending it to the main control module; the display module is connected to the main control module for displaying CAN signal identification data information; the power supply module is used to provide an adaptive power supply for the device.

2. A non-destructive and non-breaking automobile CAN bus test device according to claim 1, characterized in that: The conductive clip comprises a conductive contact piece, which is arranged at the clamping part of the conductive clip, and the conductive contact piece is connected to the induction signal interface through a wire.

3. A non-destructive and non-breaking automobile CAN bus test device according to claim 1, characterized in that: It also includes a polarity switching module, which is connected between the sensing signal interface and the CAN signal extraction module and is used to switch the polarity of the connection between the sensing signal interface and the CAN signal extraction module according to the control of the main control module.

4. A non-destructive and non-breaking automobile CAN bus test device according to claim 3, characterized in that: The polarity switching module includes a relay K1 and a switch tube Q5, the first normally open end and the second normally closed end of the relay K1 are connected to the positive end of the sensing signal interface, the second normally open end and the first normally closed end of the relay K1 are connected to the negative end of the sensing signal interface, the first common end of the relay K1 is connected to the CAN sensing low signal end, and the second common end of the relay K1 is connected to the CAN sensing high signal end. The signal polarity control end of the main control module controls the coil of the relay K1 to be energized or de-energized through the switch tube Q5.

5. The non-destructive and non-breaking automobile CAN bus test device according to claim 1 is characterized in that: The CAN signal extraction module includes a first comparator, a second comparator, an AND logic operation unit, and an OR logic operation unit; the positive input end of the first comparator is connected to the CAN sensing high signal end, and the negative input end is connected to the CAN sensing low signal end. The CAN sensing high signal end is connected to the negative input end of the second comparator after voltage division by resistors R12 and R17, and the CAN sensing low signal end is connected to the CAN signal extraction module power supply through resistors R13 and R21, and the connection point between resistors R13 and R21 is also connected to the positive input end of the second comparator; the output end of the second comparator is connected to an input end of the OR logic operation unit, the other input end of the OR logic operation unit is grounded, the output end of the OR logic operation unit is connected to an input end of the AND logic operation unit, the other input end of the AND logic operation unit is connected to the output end of the first comparator, and the output end of the AND logic operation unit is connected to the output end of the OR logic operation unit and serves as the output end of the CAN signal extraction module.

6. A non-destructive and non-breaking automobile CAN bus test device according to claim 5, characterized in that: The CAN signal conversion module includes a CAN signal conversion chip U2 and a CAN signal conversion chip U4. The CANH and CANL pins of the CAN signal conversion chip U2 and the CAN signal conversion chip U4 are both connected to the CAN signal interface. The TXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal sending end of the main control module. The RXD pin of the CAN signal conversion chip U2 is connected to the CAN logic signal receiving end of the main control module. The TXD pin of the CAN signal conversion chip U2 is connected to the output end of the CAN signal extraction module.

7. A non-destructive and non-breaking automobile CAN bus test device according to claim 1, characterized in that: The power module includes a battery, a switch tube Q1, a switch tube Q2, a two-terminal diode D4, a power switch, a resistor R9, a resistor R16, a capacitor C9, a first voltage conversion unit and a second voltage conversion unit; the positive electrode of the battery is connected to the source of the switch tube Q1, the gate of the switch tube Q1 is connected to the drain of the switch tube Q2, the source of the switch tube Q2 is grounded, the gate of the switch tube Q2 is connected to the power control end of the main control module, the resistor R16 is connected in parallel between the gate and source of the switch tube Q2; the resistor R9 is connected in parallel between the gate and source of the switch tube Q1, and the switch The gate of the tube Q1 is also connected to an anode of the two-terminal diode D4, the cathode of the diode D4 is grounded through a power switch, the other anode of the two-terminal diode D4 is connected to the switch detection end of the main control module and one end of the capacitor C9, and the other end of the capacitor C9 is grounded; the drain of the switch tube Q1 is connected to the input end of the first voltage conversion unit, and the output end of the first voltage conversion unit is connected to the input end of the second voltage conversion unit; the first voltage conversion unit is used to convert the battery output voltage into a 5V voltage, and the second voltage conversion unit is used to convert the 5V voltage into a 3.3V voltage.

8. The non-destructive and non-breaking automobile CAN bus test device according to claim 7 is characterized in that: The display module includes an OLED display screen.

9. A non-destructive and non-breaking automobile CAN bus test device according to claim 8, characterized in that: It also includes a shell, the sensing signal interface, CAN signal interface and OLED display screen are all arranged on the surface of the shell, and parts of the CAN signal extraction module, CAN signal conversion module, main control module and power supply module are all arranged on a circuit board embedded in the shell.

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