A weighing shelf weight acquisition device

Abstract

The application relates to a weight collecting device for a weighing shelf, which is composed of a plurality of weighing collecting plates, a microcontroller, a CAN communication unit and a power supply. Each weighing collecting plate is provided with a weighing collecting module and a corresponding weighing sensor. The module converts the weight analog electric signals collected by the weighing sensor into weight digital signals and transmits the weight digital signals to the microcontroller. The microcontroller calculates the weight of the goods based on the weight data signals and sends the processing results to the CAN communication unit. The power supply simultaneously supplies power to each weighing collecting module and the microcontroller. Each weighing collecting plate works independently, and when any weighing collecting plate fails, the signal collection, conversion and processing process of other weighing collecting plates will not be affected. For example, when the weighing collecting module of a certain weighing collecting plate is damaged, the microcontroller can still normally process the data transmitted by the weighing collecting modules of other weighing collecting plates, so that the system part function operation is maintained.

Description

Technical Field

[0001] This utility model relates to a weight acquisition device, specifically a weight acquisition device for a weighing shelf. Background Technology

[0002] In modern warehousing and logistics management, the intelligent and data-driven nature of racking systems has become a core industry requirement. Traditional racking systems primarily rely on static storage, depending on manual periodic inventory checks or handheld devices for random weight checks, resulting in low efficiency, significant data lag, and high rates of human error. To improve management accuracy, racking systems integrating weighing functions (referred to as "weighing racks") have gradually emerged in the market. By installing weighing sensors on the load-bearing layers of the racks, they monitor changes in the weight of goods in real time and upload the data to a warehouse management system (WMS), enabling functions such as dynamic inventory tracking and stockout alerts.

[0003] The core technology of existing weighing racks typically involves deploying resistance strain gauge or electromagnetic load cells on each layer of the rack. The sensor output signals are transmitted to a central data acquisition module via wired or wireless means, where the data is processed and uploaded to a server. While this design addresses the inefficiency of manual management to some extent, its architecture suffers from several significant drawbacks: Firstly, existing weighing racks generally employ a centralized data acquisition model, meaning all sensor signals must be processed through a single central acquisition module. If the central module or a critical transmission node (such as the bus or main control chip) fails, the entire rack's weighing function will be completely disabled. For example, if the central acquisition module of a rack is damaged by a short circuit, even if the other sensors are functioning normally, the system will be unable to acquire any weight data, leading to a standstill in warehouse management. Secondly, existing systems rely on manual troubleshooting for fault response. Because the sensors and central module are connected in series or a star configuration, a faulty sensor can interfere with the entire communication link, preventing the central module from accurately locating the fault. Maintenance personnel must disassemble the racks layer by layer to inspect the wiring or sensors, which is time-consuming, labor-intensive, and disrupts warehouse operations. Summary of the Invention

[0004] The technical problem this invention aims to solve is that, in existing weighing racks, the sensor signals are processed through a single central acquisition module, and any failure in any module during the sensor signal transmission process will cause the entire rack's weighing function to completely fail, as well as the problem that fault response relies on manual troubleshooting.

[0005] To solve the above-mentioned technical problems, this utility model provides a weight acquisition device for a weighing shelf. The acquisition device consists of several weighing acquisition boards, a microcontroller, a CAN communication unit, and a power supply. Each weighing acquisition board is equipped with a weighing acquisition module and a corresponding weighing sensor. The module converts the analog electrical signal of weight acquired by the weighing sensor into a digital signal of weight and transmits it to the microcontroller. The microcontroller calculates the weight of the item based on the weight data signal and sends the processing result to the CAN communication unit. The power supply provides power to each weighing acquisition module and the microcontroller.

[0006] The weighing acquisition module includes a power chip U6, a weighing sensor, an AD conversion chip UA1, and corresponding peripheral circuits. The input terminal of the power chip U6 is connected to the power supply through two parallel input voltage regulator capacitors C29 and C30, and its output terminal is connected to two parallel output voltage regulator capacitors C31 and C32. C27 and C34 are the power supply voltage regulator capacitors for the AD conversion chip. C28 is the coupling capacitor for pins 5 and 6 of the AD conversion chip. C35 is the coupling capacitor for the differential voltage signal output from terminal J5 of the PH4P terminal block. C37 is the voltage regulator capacitor for the reference voltage converted internally by the AD conversion chip. C38 is the coupling capacitor for the reference voltage converted internally by the AD conversion chip, used to filter out AC components in the power supply. R1 and R8 are current-limiting resistors used to limit the current of the differential voltage signal output from terminal J5. Terminal J5 of the PH4P terminal block is used to receive the load from the weighing sensor LC13. The weight analog signal acquired by chip 30 is connected as follows: pin 1 is grounded; pin 2 is connected to capacitors C34, C27, and C38, and pins 1, 4, 10, and 12 of the AD conversion chip UA1; pin 3 is connected to resistor R8, with the other end of resistor R8 connected to capacitors C35 and C36, and pin 8 of the AD conversion chip UA1; pin 4 is connected to resistor R1, with the other end of resistor R8 connected to capacitors C33 and C35, and pin 7 of the AD acquisition chip UA1; pin 14 of the AD conversion chip UA1 is connected to pin 44 (PDWN4) of the MCU chip U1; pin 15 of the AD conversion chip UA1 is connected to pin 32 (KOUT4) of the MCU chip U1; and pin 16 of the AD conversion chip UA1 is connected to pin 24 (KIN4) of the microcontroller's MCU chip U1. The AD conversion chip (UA1) and the MCU transmit data via an SPI interface. The MCU's A0 / SDCLK ​​pin is connected to the SCLK pin of the AD acquisition chip. The digital weight data converted by the AD conversion chip is output from the DRDY# / DOUT pin and connected to the MCU's A1 / SWDIO pin.

[0007] The microcontroller consists of an MCU chip U1 and corresponding peripheral circuits. The SWD debug interface J1 has pin 1 powered by +3.3V, pin 2 connected to one end of resistor R3, the other end of resistor R3 connected to pin 52 of the MCU chip U1, pin 3 connected to one end of resistor R4, the other end of resistor R4 connected to pin 51 of the MCU chip U1, and pin 4 grounded. The ISP select port has pin 1 connected to one end of resistor R5, the other end of resistor R5 connected to pin 50 of the MCU chip U1 and one end of resistor R6, the other end of resistor R6 grounded. The UART serial communication port J2 has pin 1 powered by +3.3V, pin 2 connected to one end of resistor R14, the other end of resistor R14 connected to pin 26 of the MCU chip U1, pin 3 connected to one end of resistor R16, the other end of resistor R16 connected to pin 27 of the MCU chip U1. The MCU chip U1... Pin 30 is connected to one end of capacitor C12 and resistor R11 in the RC reset circuit. The other end of C12 is grounded, and the other end of resistor R11 is connected to the +3.3V power supply. One end of resistor R9 is connected to pin 28 of U1 and one end of crystal oscillator X1. The other end of resistor R9 is connected to pin 29 of MCU chip U1 and the other end of crystal oscillator X1. The two ends of crystal oscillator X1 are connected to capacitors C7 and C9, respectively. The other ends of capacitors C7 and C9 are grounded. Capacitors C1, C2, C3, C4, C5, and C6 are power supply filter capacitors, with one end connected to the +3.3V power supply and the other end grounded. Pins 37, 39, and 41 of MCU chip U1 are connected to the negative terminal of a tri-color LED. The other end of the tri-color LED is connected to resistor R2, and the other end of resistor R2 is connected to the +3.3V power supply. Pins 3, 12, and 15 of MCU chip U1 are connected to one end of capacitors C8, C10, and C11, respectively, while the other end of capacitors C8, C10, and C11 is grounded.

[0008] Pins 1 and 2 of the CAN communication circuit interface terminal CN1 are grounded. Pin 3 (CANH) is connected to NTC thermistor R35, capacitor C25, ESD protection TVS diode D7, and surge protector D4. The other end of capacitor C25 is grounded. The third pin of ESD protection TVS diode D7 is grounded. The other end of surge protector D4 is grounded. Pin 4 (CANL) is connected to NTC thermistor R40, capacitor C26, the other end of ESD protection TVS diode D7, and surge protector D6. The other end of capacitor C26... One end is grounded, and the other end of surge protector D6 is grounded. Pins 5 and 6 are connected to unidirectional diode D3, and the other end of D3 is connected to +12V. One end of resistor R35 is connected to pin 7 of CAN chip U5, surge protector D5, and pin 2 of shorting cap pin P2. Pin 1 of shorting cap pin is connected to one end of terminating matching resistor R39. One end of resistor R40 is connected to the other end of terminating matching resistor R39, the other end of surge protector D5, and pin 6 of CAN chip U5. Pin 1 (CAN TX) of CAN chip U5 is connected to resistor R36, and the other end of resistor R36 is connected to pin 23 of MCU chip U1. Pin 4 (CAN RX) of CAN chip U5 is connected to resistor R38, and the other end of resistor R38 is connected to pin 22 of MCU chip U1. Pin 2 of CAN chip U5 is connected to pin 3, pin 3 is connected to power supply +3.3V, and pin 8 is connected to resistor R37, the other end of resistor R37 is grounded.

[0009] In use, each weighing acquisition module is installed in a different position on the weighing rack.

[0010] This utility model has the following advantages: Each weighing acquisition board operates independently. A failure in any one board will not affect the signal acquisition, conversion, and processing of other boards. For example, if the weighing acquisition module of one board fails, the microcontroller can still process the data from the weighing acquisition modules of other boards, maintaining some system functions.

[0011] The CAN bus uses differential signal transmission, transmitting complementary voltage signals through two lines, CAN_H and CAN_L. This design can effectively suppress common-mode interference. Even if a single cable is disconnected or short-circuited, the remaining lines can still transmit signals through differential voltage, and other nodes can still communicate normally. Attached Figure Description

[0012] Figure 1 This is a system block diagram of the present invention; Figure 2 Circuit diagram of the weight acquisition module: Figure 3 This is a circuit diagram for a microcontroller (MCU). Figure 4 This is a circuit diagram of a CAN communication unit. Detailed Implementation

[0013] like Figure 1 As shown, the weighing rack weight acquisition device of this utility model consists of multiple weighing acquisition boards, a CAN communication unit, a microcontroller, and a power supply. Each weighing acquisition board is equipped with a weighing acquisition module and a corresponding weighing sensor. The module converts the analog weight signal acquired by the weighing sensor into a digital weight signal and transmits it to the microcontroller. The microcontroller calculates the weight of the item based on the weight data signal and sends the processing result to the CAN communication unit. The power supply provides power to each weighing acquisition module and the microcontroller.

[0014] Figure 2 The diagram shows the circuit composition of the weighing acquisition module, which includes a power supply chip U6, a load cell, an AD conversion chip UA1, and corresponding peripheral circuits. It is used to receive the analog weight signal acquired by the load cell and perform analog-to-digital conversion and processing. The load cell is an LC1330 single-point load cell, the power supply chip U6 is an HT7533-1 power chip manufactured by Guangdong Youtai Semiconductor Co., Ltd., and the AD conversion chip UA1 is an ADS1230IPWR manufactured by Texas Instruments.

[0015] The input terminal of power chip U6 is connected to the power supply through two parallel input voltage regulator capacitors C29 and C30, and its output terminal is connected to two parallel output voltage regulator capacitors C31 and C32. The aforementioned input voltage regulator capacitors C29 and C30, as well as C31 and C32, all serve to regulate voltage and filter. C27 and C34 are the power supply voltage regulator capacitors for the AD converter chip. C28 is the coupling capacitor for pins 5 and 6 of the AD converter chip. C35 is the coupling capacitor for the differential voltage signal output from terminal J5 of the PH4P connector. C37 is the voltage regulator capacitor for the reference voltage converted internally by the AD converter chip, serving to regulate the power supply. C38 is the coupling capacitor for the reference voltage converted internally by the AD converter chip, used to filter out AC components in the power supply. R1 and R8 are current-limiting resistors used to limit the current of the differential voltage signal output from terminal J5, preventing abnormal voltage from damaging the AD converter chip.

[0016] The PH4P terminal J5 is used to receive the analog weight signal acquired by the LC1330 load cell. Its pin 1 is grounded, pin 2 is connected to capacitors C34, C27, and C38 and pins 1, 4, 10, and 12 of the AD conversion chip UA1, pin 3 is connected to resistor R8, the other end of resistor R8 is connected to capacitors C35 and C36 and pin 8 of the AD conversion chip UA1, pin 4 is connected to resistor R1, the other end of resistor R8 is connected to capacitors C33 and C35 and pin 7 of the AD acquisition chip UA1, pin 14 of the AD conversion chip UA1 is connected to pin 44 (PDWN4) of the MCU chip U1, pin 15 of the AD conversion chip UA1 is connected to pin 32 (KOUT4) of the MCU chip U1, and pin 16 of the AD conversion chip UA1 is connected to pin 24 (KIN4) of the MCU chip U1 of the microcontroller. The AD converter chip (UA1) and the MCU transmit data via an SPI interface. The MCU's A0 / SDCLK ​​pin is connected to the AD acquisition chip's SCLK pin to provide a clock signal for data transmission and ensure data synchronization. The digital weight data converted by the AD converter chip is output from the DRDY# / DOUT pin and connected to the MCU's A1 / SWDIO pin, realizing unidirectional data transmission from the AD converter chip to the MCU, allowing the MCU to use the weight data for subsequent processing.

[0017] like Figure 3As shown, the microcontroller consists of an MCU chip U1 and corresponding peripheral circuits. The MCU chip used is the SWM32SRET6 microcontroller manufactured by Guangdong Huaxin Microelectronics Integrated Circuit Co., Ltd., which has built-in functions for processing and calculating weight data signals. Pin 1 of the SWD debug interface J1 is connected to a +3.3V power supply. Pin 2 is connected to one end of resistor R3, the other end of which is connected to pin 52 of the MCU chip U1. Pin 3 is connected to one end of resistor R4, the other end of which is connected to pin 51 of the MCU chip U1. Pin 4 is grounded. Pin 1 of the ISP select port is connected to one end of resistor R5, the other end of which is connected to pin 50 of the MCU chip U1 and one end of resistor R6. The other end of resistor R6 is grounded. Pin 1 of the UART serial communication chip J2 is connected to +3.3V power. Pin 2 is connected to one end of resistor R14, and the other end of resistor R14 is connected to pin 26 of MCU chip U1. Pin 3 is connected to one end of resistor R16, and the other end of resistor R16 is connected to pin 27 of MCU chip U1. Pin 30 of MCU chip U1 is connected to capacitor C12 and one end of resistor R11 in the RC reset circuit. The other end of C12 is grounded, and the other end of resistor R11 is connected to +3.3V power. One end of resistor R9 is connected to pin 28 of MCU chip U1 and one end of crystal oscillator X1. The other end of resistor R9 is connected to pin 29 of U1 and the other end of crystal oscillator X1. The two ends of crystal oscillator X1 are connected to capacitors C7 and C9, respectively, and the other ends of capacitors C7 and C9 are grounded. Capacitors C1, C2, C3, C4, C5, and C6 are power supply filter capacitors, with one end connected to +3.3V power and the other end grounded. Pins 37, 39, and 41 of MCU chip U1 are connected to the negative terminals of a tri-color LED. The other end of the LED is connected to resistor R2, and the other end of resistor R2 is connected to a +3.3V power supply. Pins 3, 12, and 15 of MCU chip U1 are connected to one end of capacitors C8, C10, and C11, respectively. The other ends of capacitors C8, C10, and C11 are grounded.

[0018] like Figure 4As shown, pins 1 and 2 of the CAN communication circuit interface terminal CN1 are grounded. Pin 3, CANH, is connected to NTC thermistor R35, capacitor C25, ESD protection TVS diode D7, and surge protector D4. The other end of capacitor C25 is grounded. The third pin of ESD protection TVS diode D7 is grounded. The other end of surge protector D4 is grounded. Pin 4, CANL, is connected to NTC thermistor R40, capacitor C26, the other end of ESD protection TVS diode D7, and surge protector D6. The other end of capacitor C26 is grounded. The other end of surge protector D6 is grounded. Pins 5 and 6 are connected to unidirectional diode D3. The other end of D3 is connected to +12V. One end of resistor R35 is connected to pin 7 of CAN chip U5, surge protector D5, and pin 2 of shorting cap pin P2. Pin 1 of shorting cap pin is connected to one end of terminating resistor R39. One end of resistor R40 is connected to the other end of terminating resistor R39, the other end of surge protector D5, and pin 6 of CAN chip U5. Pin 1 (CAN TX) of CAN chip U5 is connected to resistor R36, and the other end of resistor R36 is connected to pin 23 of MCU chip U1. Pin 4 (CAN RX) of CAN chip U5 is connected to resistor R38, and the other end of resistor R38 is connected to pin 22 of MCU chip U1. Pin 2 of CAN chip U5 is connected to [missing information], pin 3 is connected to +3.3V power supply, and pin 8 is connected to resistor R37, the other end of which is grounded. R35 and R40 are NTC resistors that activate over-temperature protection to prevent damage to the CAN communication chip. Resistor R39 is a terminating resistor to achieve impedance matching of the CAN line.

[0019] The working principle of this invention is as follows: The output terminal of the weighing acquisition module is connected to the input pin 15SCLK of the AD conversion chip. The output pin 16, DOUT, of the AD conversion chip is connected to the input pin 24 of the microcontroller (MCU). The AD conversion chip converts the weight electrical signal into a weight data signal and sends it to the microcontroller (MCU). The microcontroller (MCU) calculates the weight of the item based on the weight data signal. The output pin of the microcontroller (MCU) is connected to the input pin of the CAN communication unit. After processing the weight data signal, the microcontroller (MCU) sends the processing result to the CAN communication unit for communication with external devices. The output terminals of the weighing acquisition module, AD conversion chip, CAN communication unit, and microcontroller (MCU) are electrically connected to the power supply. The CAN communication unit is electrically connected to the host computer.

[0020] When an item is placed on the weighing shelf, the weighing acquisition module senses its weight and converts it into an analog electrical signal. The magnitude of this analog electrical signal is proportional to the weight of the item. The AD acquisition chip receives the analog electrical signal from the weighing acquisition module, then performs analog-to-digital conversion, converting the analog signal into a digital signal. The microcontroller (MCU) receives the weight data signal from the AD acquisition chip and calculates the actual weight of the item. The microcontroller (MCU) then sends the calculated item weight data to the CAN communication unit. This invention employs an independent power supply and independent signal transmission path design. Each weighing acquisition module and microcontroller (MCU) is directly powered by the power supply module and independently connected to the system power network through its respective power pin. This parallel power supply method ensures that even if a node experiences a power failure due to a short circuit or component breakdown, the fault current is limited to the weighing acquisition board and will not affect the power supply stability of other nodes through the power bus. Simultaneously, the signal path of each weighing acquisition board is completely independent: the analog signal output from the weighing sensor directly enters the AD acquisition chip of this weighing acquisition board, undergoes analog-to-digital conversion, and is processed by the MCU. The entire process requires no intermediate processing or coordination from any central module or other nodes. This "point-to-point" closed-loop signal chain design allows each sensor node (weighing acquisition module, AD conversion chip, and related circuitry) to operate independently. The weighing acquisition module directly connects the analog electrical signal of the weight acquired by the weighing sensor to the AD conversion chip, which converts the analog signal into a digital signal before transmitting it to the microcontroller (MCU). This relatively independent connection between nodes ensures that a failure in one node will not affect the signal acquisition, conversion, and processing of other nodes. For example, if a weighing acquisition module fails, its corresponding AD conversion chip and MCU can still process data from other nodes and maintain some system functions.

[0021] In addition, the electrical design of the CAN bus also fully considers fault tolerance: through components such as resistor networks (such as R35, R40) and common-mode chokes, electrical interference that may be introduced by faulty nodes is effectively suppressed, avoiding the risk of the bus level being pulled low or short-circuited.

Claims

1. A weight acquisition device for a weighing rack, comprising several weighing acquisition boards, a microcontroller, a CAN communication unit, and a power supply. Each weighing acquisition board is equipped with a weighing acquisition module and a corresponding weighing sensor. The module converts the analog electrical signal of weight acquired by the weighing sensor into a digital signal of weight and transmits it to the microcontroller. The microcontroller calculates the weight of the item based on the weight data signal and sends the processing result to the CAN communication unit. The power supply provides power to each weighing acquisition module and the microcontroller.

2. The weighing rack weight acquisition device as described in claim 1, characterized in that... The weighing acquisition module includes a power chip U6, a weighing sensor, an AD conversion chip UA1, and corresponding peripheral circuits. The input terminal of power chip U6 is connected to the power supply through two parallel input voltage regulator capacitors C29 and C30, and its output terminal is connected to two parallel output voltage regulator capacitors C31 and C32. C27 and C34 are the power supply voltage regulator capacitors of the AD conversion chip. C28 is the coupling capacitor of pins 5 and 6 of the AD conversion chip. C35 is the coupling capacitor of the differential voltage signal output from terminal J5 of PH4P. C37 is the voltage regulator capacitor of the reference voltage converted internally by the AD conversion chip. C38 is the coupling capacitor of the reference voltage converted internally by the AD conversion chip, used to filter out the AC component in the power supply. R1 and R8 are current limiting resistors used to limit the current of the differential voltage signal output from terminal J5. The PH4P terminal J5 of the AD conversion chip is used to receive the analog weight signal acquired by the LC1330 load cell. Its pin 1 is grounded; pin 2 is connected to capacitors C34, C27, and C38, and pins 1, 4, 10, and 12 of the AD conversion chip UA1; pin 3 is connected to resistor R8, with the other end of resistor R8 connected to capacitors C35 and C36, and pin 8 of the AD conversion chip UA1; pin 4 is connected to resistor R1, with the other end of resistor R8 connected to capacitors C33 and C35, and pin 7 of the AD acquisition chip UA1; pin 14 of the AD conversion chip UA1 is connected to pin 44 (PDWN4) of the MCU chip U1; pin 15 of the AD conversion chip UA1 is connected to pin 32 (KOUT4) of the MCU chip U1; and pin 16 of the AD conversion chip UA1 is connected to pin 24 (KIN4) of the microcontroller's MCU chip U1. The AD conversion chip UA1 and the MCU transmit data via an SPI interface; the MCU's A0 / SDCLK... The pin is connected to the SCLK pin of the AD acquisition chip. The digital weight data converted by the AD conversion chip is output from the DRDY# / DOUT pin and connected to the A1 / SWDIO pin of the MCU.

3. The weighing rack weight acquisition device as described in claim 1, characterized in that... The microcontroller consists of an MCU chip U1 and corresponding peripheral circuits. Pin 1 of the SWD debug interface J1 is powered by +3.3V. Pin 2 is connected to one end of resistor R3. The other end of resistor R3 is connected to pin 52 of the MCU chip U1. Pin 3 is connected to one end of resistor R4. The other end of resistor R4 is connected to pin 51 of the MCU chip U1. Pin 4 is grounded. Pin 1 of the ISP select port is connected to one end of resistor R5. The other end of resistor R5 is connected to pin 50 of the MCU chip U1 and one end of resistor R6. The other end of resistor R6 is grounded. Pin 1 of the UART serial communication J2 is connected to +3.3V power. Pin 2 is connected to one end of resistor R14, and the other end of resistor R14 is connected to pin 26 of MCU chip U1. Pin 3 is connected to one end of resistor R16, and the other end of resistor R16 is connected to pin 27 of MCU chip U1. Pin 30 of MCU chip U1 is connected to capacitor C12 and one end of resistor R11 in the RC reset circuit. The other end of C12 is grounded, and the other end of resistor R11 is connected to the +3.3V power supply. One end of resistor R9 is connected to pin 28 of U1 and one end of crystal oscillator X1. The other end of resistor R9 is connected to pin 29 of MCU chip U1 and the other end of crystal oscillator X1. The two ends of crystal oscillator X1 are connected to capacitors C7 and C9 respectively, and the other ends of capacitors C7 and C9 are grounded. Capacitors C1, C2, C3, C4, C5 and C6 are power supply filter capacitors, one end of which is connected to the +3.3V power supply, and the other end is grounded. Pins 37, 39 and 41 of MCU chip U1 are connected to the negative terminal of the tri-color LED respectively. The other end of the tri-color LED is connected to resistor R2, and the other end of resistor R2 is connected to the +3.3V power supply. Pins 3, 12 and 15 of MCU chip U1 are connected to one end of capacitors C8, C10 and C11 respectively, and the other ends of capacitors C8, C10 and C11 are grounded.

4. The weighing shelf weight acquisition device as described in claim 1, characterized in that... Pins 1 and 2 of the CAN communication unit interface terminal CN1 are grounded. Pin 3 (CANH) is connected to NTC thermistor R35, capacitor C25, ESD protection TVS diode D7, and surge protector D4. The other end of capacitor C25 is grounded. The third pin of ESD protection TVS diode D7 is grounded. The other end of surge protector D4 is grounded. Pin 4 (CANL) is connected to NTC thermistor R40, capacitor C26, the other end of ESD protection TVS diode D7, and surge protector D6. The other end of capacitor C26... One end is grounded, and the other end of surge protector D6 is grounded. Pins 5 and 6 are connected to unidirectional diode D3, and the other end of D3 is connected to +12V. One end of resistor R35 is connected to pin 7 of CAN chip U5, surge protector D5, and pin 2 of shorting cap pin P2. Pin 1 of shorting cap pin is connected to one end of terminating matching resistor R39. One end of resistor R40 is connected to the other end of terminating matching resistor R39, the other end of surge protector D5, and pin 6 of CAN chip U5. Pin 1 (CAN TX) of CAN chip U5 is connected to resistor R36, and the other end of resistor R36 is connected to pin 23 of MCU chip U1. Pin 4 (CAN RX) of CAN chip U5 is connected to resistor R38, and the other end of resistor R38 is connected to pin 22 of MCU chip U1. Pin 2 of CAN chip U5 is connected to pin 3, pin 3 is connected to power supply +3.3V, and pin 8 is connected to resistor R37, the other end of resistor R37 is grounded.

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