CN211236074U

CN211236074U - Accidental fault on-line detection and recording device

Info

Publication number: CN211236074U
Application number: CN201922148294.3U
Authority: CN
Inventors: 张敏海; 伍丰; 蒋逢灵
Original assignee: Hunan Vocational College of Railway Technology
Current assignee: Hunan Vocational College of Railway Technology
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2020-08-11
Anticipated expiration: 2029-12-04

Abstract

The utility model discloses an accidental fault on-line detection and recording device, which comprises a multi-path digital isolation input circuit, a multi-path analog quantity acquisition adjusting circuit, a power circuit, a storage circuit, a serial communication RS232 circuit, a CAN communication circuit, a clock circuit and a master control MCU; after the vehicle has accidental faults, the device can comprehensively record the accidental faults, and the phenomenon that some fault information which possibly influences the normal operation of the vehicle is lost due to the fact that the whole vehicle control system does not record the faults or the information is incompletely recorded is avoided.

Description

Accidental fault on-line detection and recording device

Technical Field

The utility model relates to an accidental trouble on-line measuring and recorder.

Background

The engineering vehicle has the characteristics of strong vibration, high working strength, harsh environment and the like; the vehicle is easy to have the conditions of poor line contact, unstable work of electrical parts and the like under the severe environment with large vibration for a long time, so that the electrical fault is caused, partial faults have the characteristic of sporadic nature and are mainly characterized in that the duration is uncertain and can be in millisecond or second grade, in addition, the faults also have the characteristic of self-recovery, after the faults last for a certain time, the faults automatically recover to normal or the temporarily normal operation is automatically recovered after the system is electrified again due to the change of the vibration condition or the environment condition, because the fault phenomenon of the faults usually disappears after maintenance personnel arrive at the site, if the fault is not recorded or the information recording is incomplete by the whole vehicle control system, the fault maintenance difficulty is extremely high, the normal operation of the vehicle is seriously influenced by the existence of the faults, partial faults can cause the insufficient traction power of the vehicle, the fault can cause the occurrence of the fault, the fault, The braking is unstable and even the working capacity is completely lost.

SUMMERY OF THE UTILITY MODEL

The utility model aims at the above problem, the utility model provides an occasional trouble on-line measuring and recorder, the vehicle emergence occasional trouble back, this device can carry out comprehensive record to the accidental trouble, avoids because whole car control system does not take notes this trouble or information record is incomplete and lead to losing some fault information that can influence vehicle normal operating.

In order to realize the above purpose, the utility model adopts the technical scheme that: an accidental fault online detection and recording device comprises a multi-path digital isolation input circuit, a multi-path analog quantity acquisition adjusting circuit, a power circuit, a storage circuit, a serial communication RS232 circuit, a CAN communication circuit, a clock circuit and a master control MCU; the main control MCU adopts a TMS320F28035 DSP model chip, an IO port of the main control MCU is connected to a digital isolation input circuit for performing photoelectric isolation on an input signal, an AI port of the main control MCU is connected to an analog quantity acquisition adjusting circuit for eliminating line common mode interference, an IIC bus port of the main control MCU is respectively connected to an external storage circuit for storing fault information state data and a clock circuit for recording the time point of fault occurrence, a CAN communication port of the main control MCU is connected to a CAN communication circuit for communicating with a vehicle control system, and a serial port of the main control MCU is connected to an external serial communication RS232 circuit for communicating with an upper computer; the power supply circuit is a power supply for converting an external circuit into a power supply for the device.

Further, the digital isolation input circuit performs photoelectric isolation on an input signal through a TLP521GB photoelectric coupling chip U6, a pin 1 of an optical coupler of the chip U6 is connected to a pin 2 of a connector P4 after passing through a current limiting resistor R1, a pin 4 of the optical coupler is connected to a resistor R6 and then connected to a power supply VCC, a port 2 is connected to a negative terminal of an external input, a port 3 is connected to a power ground, and the port 4 is simultaneously connected to a DI1 interface of the control MCU.

Further, the CAN communication circuit comprises an ISO1050 chip U4, a port 2 and a port 3 of the chip U4 are respectively connected to a CANRXD port and a CANTXD port on the main control MCU, a port 6 and a port 7 of the chip U4 are respectively connected to a resistor R5 and a resistor R3, one ends of the resistor R5 and the resistor R3 are respectively connected to one end of the resistor R4, and the other ends of the resistor R5 and the resistor R3 are respectively connected to a port 1 and a port 2 of a CAN bus P3.

Further, the serial communication RS232 circuit adopts a MAX232 chip U2 for level conversion, pin 13 of the chip U2 is connected to pin RXD1 of the main control MCU, pin 11 of the chip U2 is connected to pin TXD1 of the main control MCU, pin 1 and pin 3 of the chip U2 are connected with a capacitor C7, pin 4 and pin 5 are connected with a capacitor C8, pin 2 is connected with a capacitor C6, pin 6 is connected with a power ground with a capacitor C9, pin 14 is connected to pin 2 of the DB9 serial port connector, pin 12 is connected to pin 3 of the DB9 serial port connector, pin 5 of the DB9 serial port connector is connected with the power ground, and the DB9 connector of the serial communication RS232 circuit is in communication connection with the upper computer.

Further, the storage circuit adopts a BL24C04F storage U3; the port 5 of the memory U3 is connected with a resistor R15, the port 6 is connected with a resistor R14, the other ends of the resistors R14 and R15 are connected with a rear power supply VCC, the port 8 is connected with a power supply, the

ports

2 and 3 are respectively connected with the A1 and A2 ports of the main control MCU, and the port 5 and the port 6 are simultaneously connected with the SDA and SCL pins of the main control MCU.

Furthermore, the clock circuit adopts a DS1302 chip U8 for recording the time point of the occurrence of the fault, and

pins

5, 6, and 7 of the chip U8 are respectively connected to pins CE, SDA, and SCL of the master MCU; a battery B1 is connected between the pin 8 and the pin 4 of the chip U8, the pin 4 of the chip U8 is also connected to a power ground, the pin 1 of the chip U8 is connected to VCC, and a crystal oscillator X2 is connected between the pin 2 and the pin 3 of the chip U8.

Further, the analog quantity acquisition adjusting circuit adopts a differential amplifying circuit, an OP07CD operational amplifying chip U5 is adopted, a pin 2 of the operational amplifying chip U5 is connected with a resistor R7, a resistor R10 and a capacitor C11, the other end of the resistor R7 is connected with a pin 2 of the capacitor C7, a resistor R7 and an input connector P7, the other ends of the resistors R7 and C7 are connected with the resistor R7, the other end of the resistor R7 is connected with a pin 6 of the U7, a pin 3 of the operational amplifying chip U7 is connected with the resistor R7, the resistor R7 and the capacitor C7, the other end of the resistor R7 is connected with the other end of the capacitor C7, the other end of the resistor R7 and a pin 1 of the input connector P7, the other ends of the resistors R7 and C7 are connected with anodes of the AGND 7 and a voltage regulator D7, and a cathode of the MCU 7 is also connected with an AI pin 72 of the main controller.

Further, the power circuit chip U30 converts a vehicle-mounted 9-36V power supply into a 5V power supply to supply power to the sensor circuit, the chip U7 and the chip U29, the input end of the power circuit chip is connected with a diode D1 for preventing the circuit from being burnt due to reverse connection of a 24V power supply, the capacitor C61 and the capacitor C62 are input filter capacitors of the chip U30, and the capacitor C63 and the capacitor C64 are output filter capacitors of the chip U30; the U29 converts the 5V power supply output by the U30 into a 3.3V power supply to supply power to the chip, and the capacitor C65 and the capacitor C66 are output filter capacitors; the input end of the chip U7 is connected with the output end of the diode D1, a 24V power supply is converted into a 5V power supply to supply power to the U4, and an isolation power supply for CAN communication is provided; the capacitor C15 and the capacitor C14 are output filter capacitors of the chip U7; a point inductance L1 for canceling mutual interference between the digital ground GND and the analog ground AGND is connected between the power supplies ADND and GND.

The utility model has the advantages that: after the vehicle occasionally trouble appears, maintenance personal causes the possible reason of trouble according to the analysis of trouble phenomenon, again as required with this device digit, simulation input port is connected to the circuit that needs the monitoring on, set up the logic that triggers the fault record through host computer software, in case satisfy the fault trigger record condition of this device, vehicle information in the nearest a period when this device can the automatic recording trouble take place, maintenance personal looks over the fault information record condition of this device through host computer software, in order to help troubleshooting, the reducible vehicle fault rate, the efficiency of maintenance is improved, multiplicable vehicle operation security simultaneously.

Drawings

Fig. 1 is a schematic block diagram of the present invention.

Fig. 2 is the utility model discloses master control MCU binding post schematic diagram.

Fig. 3 is a diagram of the digital isolation input circuit of the present invention.

Fig. 4 is the CAN communication circuit diagram of the present invention.

Fig. 5 is a circuit diagram of the serial communication RS232 of the present invention.

Fig. 6 is a circuit diagram of the memory of the present invention.

Fig. 7 is a clock circuit diagram of the present invention.

Fig. 8 is a circuit diagram for adjusting analog acquisition according to the present invention.

Fig. 9 is a power circuit diagram of the present invention.

Fig. 10 is a control flow block diagram of the present invention.

Detailed Description

In order to make the technical solution of the present invention better understood, the present invention is described in detail below with reference to the accompanying drawings, and the description of the present invention is only exemplary and explanatory, and should not be construed as limiting the scope of the present invention.

As shown in fig. 2, the main control MCU adopts a TMS320F28035 chip, and a multi-channel digital isolation input circuit, a multi-channel analog acquisition adjustment circuit, a CAN communication port, a serial communication RS232 port, a clock circuit, a storage circuit, and the like are connected to the periphery of the main control MCU.

As shown in fig. 1, an on-line monitoring and recording device for accidental faults comprises a digital isolation input circuit, an analog quantity acquisition adjusting circuit, a power circuit, a storage circuit, a serial communication RS232 circuit, a CAN communication circuit, a clock circuit and a master control MCU; the utility model discloses a control system, including master control MCU, digital isolation input circuit, clock circuit, master control MCU's IO port, IIC bus port, clock circuit, CAN communication port, master control MCU's serial port is connected to the external serial communication RS232 circuit that is connected with host computer communication, master control MCU's IO port is connected to the optoelectronic isolation that digital isolation input circuit realized input signal, master control MCU's AI port is connected to the analog quantity acquisition adjustment circuit who eliminates the common mode interference of circuit, master control MCU's IIC bus port is connected to the external memory circuit who is used for the storage of fault information state data and the clock circuit of the time point that takes place of record trouble respectively, master control MCU's CAN communication port is connected to and is used for communicating with whole car control system, acquires vehicle operation data.

This device passes through digital isolation input circuit and converts the switching signal of accessible master control MCU collection with outside digital signal, through analog acquisition regulating circuit with outside analog signal conversion the analog signal that the AI port of accessible master control MCU gathered, still acquire signals such as on-vehicle speed, fender position through CAN bus circuit, these data that this device will gather are compared with the fault trigger threshold value of settlement, if satisfy the fault trigger condition, then deposit the data of gathering and the current time that obtains from clock circuit in storage circuit's data memory chip together, affiliated fault trigger threshold value carries out RS232 communication through host computer and this device, revise the settlement on host computer software.

As shown in fig. 3, the digital isolation input circuit adopts a TLP521GB photocoupling chip U6 to perform photoelectric isolation on an input signal, a pin 1 of the photocoupler is connected to a pin 2 of a connector P4 after passing through a current limiting resistor R1, a pin 4 of the photocoupler is connected to a resistor R6 and then connected to a power supply VCC, a port 2 is connected to a negative terminal of an external input, a port 3 is connected to a power ground, and the port 4 is simultaneously connected to a DI1 interface of a control MCU. The digital isolation input circuit converts an external digital quantity signal input to the P4 port into a digital signal which can be collected by the MCU port after isolation conversion, and the input digital signal can be a temperature switch signal, a relay signal and the like on the vehicle.

Optionally, a multi-channel digital isolation input circuit may be used as required, and the device includes 8 channels, which are respectively connected to the pins DI1, DI2, DI3, DI4, DI5, DI6, DI7, and DI8 of the main control MCU.

Preferably, as shown in fig. 4, the CAN communication circuit includes an ISO1050 chip U4, a port 2 and a port 3 of the chip U4 are respectively connected to a CANRXD port and a CANTXD port on the main control MCU, a port 6 and a port 7 of the chip U4 are respectively connected to a resistor R5 and a resistor R3, one ends of the resistor R5 and the resistor R3 are respectively connected to one end of the resistor R4, the other ends of the resistor R5 and the resistor R3 are respectively connected to a port 1 and a port 2 of a CAN bus P3, and the CAN communication circuit is used for communicating with a vehicle control system to obtain vehicle operation data, such as vehicle speed, gear, accelerator pedal, brake pedal, traction torque, and the like.

Preferably, as shown in fig. 5, the serial communication RS232 circuit uses a MAX232 chip U2 for level conversion, pin 13 of the chip U2 is connected to pin RXD1 of the master MCU, pin 11 of the chip U2 is connected to pin TXD1 of the master MCU, pin 1 and pin 3 of the chip U2 are connected with capacitor C7, pin 4 and pin 5 are connected with capacitor C8, pin 2 and power VCC are connected with capacitor C6, pin 6 and power ground are connected with capacitor C9, pin 14 is connected to pin 2 of the DB9 serial port connector, pin 12 is connected to pin 3 of the DB9 serial port connector, pin 5 of the DB9 serial port is connected to power ground, and the DB9 connector of the serial communication RS232 circuit is used for communication connection with an upper computer to configure parameters and read information of the apparatus; the device can configure parameters for triggering alarm through microcomputer software, for example, when a certain digital input port meets the level condition, a fault storage operation is triggered to facilitate fault analysis.

Preferably, as shown in fig. 6, the memory circuit adopts a BL24C04F memory U3, a port 5 of the memory circuit is connected with a resistor R15, a port 6 of the memory circuit is connected with a resistor R14, the other ends of the resistors R14 and R15 are connected with a rear power supply VCC, a port 8 of the memory circuit is connected with a power supply,

ports

2 and 3 of the memory circuit are respectively connected with ports a1 and a2 of the master MCU, and the

ports

5 and 6 are also connected to pins SDA and SCL of the master MCU; the storage circuit is used for storing the vehicle fault information state data.

Preferably, the memory circuit may also be a FLASH circuit, an EEPROM circuit, or a ferroelectric memory circuit.

Preferably, as shown in fig. 7, the clock circuit adopts a DS1302 chip U8 for recording the time point of the fault occurrence,

pins

5, 6, and 7 of the chip U8 are respectively connected to pins CE, SDA, and SCL of the master MCU; a battery B1 is connected between the pin 8 and the pin 4 of the U8, the pin 4 of the U8 is also connected to a power ground, the pin 1 of the U8 is connected to VCC, and a crystal oscillator X2 is connected between the pin 2 and the pin 3 of the U8.

Preferably, as shown in fig. 8, the analog quantity collecting and adjusting circuit employs a differential amplifying circuit to eliminate common mode interference of the lines, an OP07CD operational amplifier chip U5 is employed, a 2-pin of the operational amplifier chip U5 is connected with a resistor R7, a resistor R10 and a capacitor C11, the other end of the resistor R7 is connected to a capacitor C12, a resistor R9 and a 2-pin of an input connector P1, the other ends of the resistors R10 and C11 are connected to the resistor R12, the other end of the resistor R12 is connected to a 6-pin of the U5, a 3-pin of the operational amplifier chip U5 is connected with a resistor R8, the other ends of the resistor R11 and the capacitor C10 are connected to the other ends of the capacitor C12 and the resistor R9 and the pin 1 of the input connector P1, the other ends of the resistor R11 and the capacitor C10 are connected to AGND and the anode of a voltage regulator tube D2, the cathode of the voltage regulator tube D2 is connected to the common end of the resistor R10 and the resistor R12, and the cathode of the voltage regulator tube D2 is also connected to the AI1 pin of the main control MCU; the voltage regulator tube D2 is used for protecting pins of the main control MCU and preventing overvoltage from damaging an AD port of the main control MCU. The input end of the analog quantity acquisition adjusting circuit is connected to an analog signal port needing to be monitored on the vehicle, and the analog signal is converted into an analog signal which can be acquired through the master control MCU analog port after passing through the analog signal port, wherein the signal can be a sensor signal with continuous changes of temperature, pressure and the like.

Optionally, a multi-channel analog quantity acquisition adjusting circuit may be actually used as required, and the device includes 6 channels, where the 6 channels of signals are respectively connected to pins AI1, AI2, AI3, AI4, AI5, and AI6 of the main control MCU.

A power circuit of the accidental fault on-line monitoring and recording device is shown in fig. 9, a U30 is used for converting a vehicle-mounted 9-36V power supply into a 5V power supply to supply power to a sensor circuit, a U7 and a U29, the input end of the power circuit is connected with a diode D1 used for preventing the circuit from being burnt due to reverse connection of a 24V power supply, a capacitor C61 and a capacitor C62 are input filter capacitors of U30, and a capacitor C63 and a capacitor C64 are output filter capacitors of U30; the U29 is used for converting a 5V power supply output by the U30 into a 3.3V power supply to supply power to the chip, and the capacitor C65 and the capacitor C66 are output filter capacitors; the input end of the U7 is connected with the output end of the diode D1, and is used for converting a 24V power supply into a 5V power supply to supply power to the U4 and provide an isolated power supply for CAN communication; the capacitor C15 and the capacitor C14 are output filter capacitors of U7; a point inductance L1 is connected between the power supplies ADND and GND to eliminate mutual interference between the digital ground GND and the analog ground AGND.

A control method of an accidental fault on-line monitoring and recording device, as shown in fig. 10, includes the following steps:

step 1: reading the state of the memory U3 through a computer, reading the configuration data of the device from the memory U3, such as triggering fault storage configuration parameters, and entering the step 2 after the processing is finished;

step 2: processing CAN communication tasks, wherein a CAN bus application layer protocol adopts an SAJ1939 bus protocol widely adopted on engineering vehicles, the device acquires information such as the rotating speed, the gear and the like of an engine from a CAN communication bus of the whole vehicle, and the step 3 is carried out after the processing is finished;

and step 3: judging whether an RS232 communication task exists or not, if not, directly entering the step 4, otherwise, responding to a trigger fault storage configuration parameter of the upper computer and putting the trigger fault storage configuration parameter into a memory for power-off storage, or responding to a fault information reading recording instruction of the upper computer, and entering the step 4 after the processing is finished;

and 4, step 4: the master control MCU acquires external DI input information of the specified number of paths according to needs through an external isolation input circuit and acquires AI input information of the specified number of paths through an analog quantity acquisition adjusting circuit, and filtering is performed; after the processing is finished, the step 5 is carried out, and the specific physical meanings of the input signals are changed according to different signals connected to the external signals;

and 5: establishing a memory buffer area in the main control MCU, putting newly acquired data into the memory buffer area, covering the oldest data, and entering step 6 after the data is finished;

step 6: judging whether the latest data meets the condition for triggering fault storage, if so, entering a step 7 to acquire the time of the fault, otherwise, returning to the step 2;

and 7: step 8 is entered after the current calendar time is obtained;

and 8: and recording fault information, writing all data in the data buffer area into an external memory, and returning to the step 2 after the data is completely written.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The principles and embodiments of the present invention have been explained herein using specific examples, which are presented only to assist in understanding the methods and their core concepts. The foregoing is only a preferred embodiment of the present invention, and it should be noted that there are objectively infinite specific structures due to the limited character expressions, and it will be apparent to those skilled in the art that a plurality of modifications, decorations or changes can be made without departing from the principle of the present invention, and the above technical features can be combined in a proper manner; the application of these modifications, variations or combinations, or the application of the concepts and solutions of the present invention in other contexts without modification, is not intended to be considered as a limitation of the present invention.

Claims

1. An accidental fault online detection and recording device is characterized by comprising a multi-path digital isolation input circuit, a multi-path analog quantity acquisition adjusting circuit, a power circuit, a storage circuit, a serial communication RS232 circuit, a CAN communication circuit, a clock circuit and a master control MCU; the main control MCU adopts a TMS320F28035 DSP model chip, an IO port of the main control MCU is connected to a digital isolation input circuit for performing photoelectric isolation on an input signal, an AI port of the main control MCU is connected to an analog quantity acquisition adjusting circuit for eliminating line common mode interference, an IIC bus port of the main control MCU is respectively connected to an external storage circuit for storing fault information state data and a clock circuit for recording the time point of fault occurrence, a CAN communication port of the main control MCU is connected to a CAN communication circuit for communicating with a vehicle control system, and a serial port of the main control MCU is connected to an external serial communication RS232 circuit for communicating with an upper computer; the power supply circuit is a power supply for converting an external circuit into a power supply for the device.

2. The device as claimed in claim 1, wherein the digital isolation input circuit photoelectrically isolates the input signal through a TLP521GB photocoupling chip U6, pin 1 of an optocoupler of chip U6 is connected to pin 2 of a connector P4 after passing through a current limiting resistor R1, pin 4 of the optocoupler is connected to a resistor R6 and then connected to a power VCC, port 2 is connected to a negative terminal of an external input, port 3 is connected to a power ground, and port 4 is simultaneously connected to a DI1 interface of the control MCU.

3. The on-line detection and recording device for the accidental fault as claimed in claim 1, wherein the CAN communication circuit comprises an ISO1050 chip U4, the port 2 and the port 3 of the chip U4 are respectively connected to CANRXD and CANTXD ports on the master MCU, the port 6 and the port 7 of the chip U4 are respectively connected with a resistor R5 and a resistor R3, one ends of the resistor R5 and the resistor R3 are respectively connected with one end of the resistor R4, and the other ends of the resistor R5 and the resistor R3 are respectively connected with the port 1 and the port 2 of the CAN bus P3.

4. The device as claimed in claim 1, wherein the serial communication RS232 circuit adopts a MAX232 chip U2 for level conversion, pin 13 of the chip U2 is connected to pin RXD1 of the master MCU, pin 11 of the chip U2 is connected to pin TXD1 of the master MCU, pin 1 and pin 3 of the chip U2 are connected with a capacitor C7, pin 4 and pin 5 are connected with a capacitor C8, pin 2 and power VCC are connected with a capacitor C6, pin 6 and power ground are connected with a capacitor C9, pin 14 is connected to pin 2 of the DB9 serial connector, pin 12 is connected to pin 3 of the DB9 serial connector, pin 5 of the DB9 serial connector is connected to power ground, and the DB9 connector of the serial communication RS232 circuit is connected to the upper computer.

5. The on-line detection and recording device for the accidental fault as claimed in claim 1, wherein the storage circuit adopts a BL24C04F storage U3; the port 5 of the memory U3d is connected with a resistor R15, the port 6 is connected with a resistor R14, the other ends of the resistors R14 and R15 are connected with a rear power supply VCC, the port 8 is connected with a power supply, the ports 2 and 3 are respectively connected with the A1 and A2 ports of the main control MCU, and the port 5 and the port 6 are simultaneously connected with the SDA and SCL pins of the main control MCU.

6. The device for on-line detection and recording of accidental faults according to claim 1, wherein the clock circuit employs a DS1302 chip U8 for recording the time point of the occurrence of the fault, pins 5, 6 and 7 of the chip U8 are respectively connected to pins CE, SDA and SCL of the master MCU; a battery B1 is connected between the pin 8 and the pin 4 of the chip U8, the pin 4 of the chip U8 is also connected to a power ground, the pin 1 of the chip U8 is connected to VCC, and a crystal oscillator X2 is connected between the pin 2 and the pin 3 of the chip U8.

7. The on-line detection and recording device for occasional faults as claimed in claim 1, the analog quantity acquisition adjusting circuit adopts a differential amplifying circuit, an OP07CD operational amplifying chip U5 is adopted, a2 pin of the operational amplifying chip U5 is connected with a resistor R7, a resistor R10 and a capacitor C11, the other end of the resistor R7 is connected with a capacitor C7, a resistor R7 and a2 pin of an input connector P7, the other ends of the resistors R7 and C7 are connected with a resistor R7, the other end of the resistor R7 is connected with a 6 pin of the U7, a 3 pin of the operational amplifying chip U7 is connected with a resistor R7, a resistor R7 and a capacitor C7, the other end of the resistor R7 is connected with the other end of the capacitor C7, the other end of the resistor R7 and a1 pin of the input connector P7, the other ends of the R7 and the C7 are connected with anodes of an AGND and a voltage stabilizing tube D7, a cathode of the voltage stabilizing tube D7 is connected with the common ends of the R7 and the cathode 7.

8. The on-line accidental fault detection and recording device of claim 1, wherein the power circuit chip U30 converts a vehicle-mounted 9-36V power supply into a 5V power supply to supply power to the sensor circuit, the chip U7 and the chip U29, a diode D1 for preventing the circuit from being burnt due to reverse connection of the 24V power supply is connected to the input end of the power circuit chip U30, the capacitor C61 and the capacitor C62 are input filter capacitors of the chip U30, and the capacitor C63 and the capacitor C64 are output filter capacitors of the chip U30; the U29 converts the 5V power supply output by the U30 into a 3.3V power supply to supply power to the chip, and the capacitor C65 and the capacitor C66 are output filter capacitors; the input end of the chip U7 is connected with the output end of the diode D1, a 24V power supply is converted into a 5V power supply to supply power to the U4, and an isolation power supply for CAN communication is provided; the capacitor C15 and the capacitor C14 are output filter capacitors of the chip U7; a point inductance L1 for canceling mutual interference between the digital ground GND and the analog ground AGND is connected between the power supplies ADND and GND.