CN110597225A - A kind of off-line detection equipment and test method based on CAN bus body controller product - Google Patents

Abstract

The invention provides a CAN bus-based vehicle body controller product offline detection device and a CAN bus-based vehicle body controller product offline detection method. The invention has strong universality, the design of the PCB test board is adopted, a commercial test board card is not adopted, the equipment construction cost can be greatly reduced, the off-line detection equipment can be repeatedly utilized, testers do not need to participate in the operation in the test process, the upper computer test software programs and modifies the test sequence according to the product difference, the test time is reduced, the input and output signals of the tested BCM are automatically tested and judged by the test equipment, the human errors are reduced, and the test accuracy is improved.

Description

A kind of off-line detection equipment and test method based on CAN bus body controller product

technical field

The invention belongs to the technical field of body controllers for automotive electronic components, and in particular relates to a CAN bus-based body controller product off-line detection equipment and testing method

Background technique

The body controller (BCM) has become an essential part of the car, which can reduce the use of on-board relays, effectively control the car's electrical appliances, and the driver can control the car's internal and external lighting systems, central locking system, Front and rear wiper systems, glass sunroof systems, rearview mirror systems, etc., BCM integrates CAN/LIN bus network control. Off-line inspection is an important link to ensure the quality of the body controller before loading. At present, the use of CAN data communication to test the body controller has become the main trend in the market. Based on the diagnostic service of BCM products, the input and output of the body controller are controlled through IO Control It is the most common test method. Combining computer automated testing improves the efficiency of offline testing. At present, Agilent’s test boards, NI’s boards and VT’s test boards are used as auxiliary tests for a series of digital and communication test boards. The production cost of boards and offline testing equipment is high.

Contents of the invention

In view of this, the present invention aims to propose a CAN bus-based vehicle body controller product off-line testing equipment to reduce the production cost of the off-line testing equipment for the vehicle body controller, improve detection efficiency, and simplify the testing process.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A product off-line detection equipment based on CAN bus body controller, including program-controlled power supply, PCB test board, test fixture and load box, CAN communication tool, upper computer, and load module;

The program-controlled power supply is used to supply power to the PCB test board, test fixture and load box, and to control the power supply to the tested BCM at the same time;

The PCB test board is used for validating corresponding digital input signals, collecting BCM output signals, valid analog signal input, CAN bus communication, valid PWM input signal, and power input for the tested BCM;

The test fixture and the load box are used to simulate the state of the electrical appliances of the vehicle, and the power consumption after the tested BCM output is effective is realized by connecting the power resistor in series;

The CAN communication tool is used for the transmission of CAN bus signals and the sending and receiving of signal commands;

The host computer sends test commands through CAN bus control, and waits for test feedback to judge test results.

Further, the output signal of the PCB test board adopts a general-purpose four-channel independently selected switch driver chip, which is used to realize the digital high and low effective output, and provides the high effective input signal and the low effective input signal of the BCM to be tested. A variety of resistance circuits are designed at the switch end to realize the serial connection of different resistance values to the ground, realize the output of different AD signals, and realize the test of different AD inputs of the BCM under test. The BCM under test reads different AD values. To judge whether the input channel is normal, the input signal adopts the extended input acquisition 151 chip, which can realize many input acquisitions, and the output of the tested BCM is collected with high and low efficiency, and the extended input channel meets the generality test of the tested BCM.

Further, the PCB board circuit includes a switch circuit, a low effective switch value acquisition circuit, and a high effective switch value acquisition circuit.

Further, the switch circuit includes a channel multifunctional switch chip U1, the IN1 pin of U1 is grounded through the pull-down resistor R1, and connected to the control output pin CRT1 of the MCU, CRT1 can pull IN1 to a high level, and the S1A pin of U1 is connected to VSS power supply, D1 pin is connected to board output pin OUT1, S1B pin is grounded; U1's VSS pin is connected to system power supply VSS, GND pin is connected to system ground GND; U1's S2B pin is connected to system power supply VSS, D2 pin is connected to board output OUT2 and IN2 pins are connected to the ground through the pull-down resistor R2, and connected to the control output pin CRT2 of the MCU, and CRT2 can pull IN1 to a high level; the IN3 pin of U1 is grounded through the pull-down resistor R3, and connected to the control output pin of the MCU CRT3, CRT3 can pull IN1 to a high level; U1’s S3A pin is grounded through a variable resistor R5, D3 pin is connected to the board output pin OUT3, and S3B pin is suspended; U1’s VDD pin is connected to MCU power supply VDD; U1’s IN4 pin The pull-down resistor R4 is grounded and connected to the control output pin CRT4 of the MCU, and CRT4 can pull IN1 to a high level. The S4A pin of U1 is grounded through the variable resistor R6, the D4 pin is connected to the board output pin OUT4, and the S4B pin is suspended.

Further, the low effective switching quantity acquisition circuit is used for testing the low effective output circuit of the BCM under test, L-IN is an effective low input signal corresponding to the effective low output signal of the BCM under test, and the L-IN signal is pulled through Resistor R10 is connected to system power supply VSS, connected to ground through capacitor C1, C1 is used for signal filtering and anti-static; connected to the input pin HC151-DX of expansion chip HC151 through series resistor R11 and parallel capacitor C2 to ground.

Further, the high-effective switching value collection is used for testing the high-effective output circuit of the BCM under test, H-IN is a high-effective input signal corresponding to the high-effective output signal of the BCM under test, and the H-IN signal passes through the filter capacitor C3 and the pull-down resistor R12 are grounded, C3 is used for signal filtering and anti-static, and R12 is used to pull down the H-IN signal to a low level when the BCM has no output; it is connected to the extension through the series resistor R13 and the ground parallel capacitor C2 The input pin HC151-DX of the chip HC151.

Further, the test fixture adopts the mechanical structure of the relay to control the solenoid valve, and the automatic connection test of the tested BCM includes external relays, solenoid valves, indicator lights, metal contact switches, and photoelectric sensors.

Further, the interface of the host computer adopts a visual window design to realize manual debugging and automatic testing. Manual testing is divided into digital input, analog input, and digital output testing. The CAN sending function is called by the switch button to perform the test command of the tested BCM. Control the BCM under test and test the PCB board.

Another object of the present invention is to propose a kind of test method based on CAN bus vehicle body controller product off-line detection equipment, concrete realization process is as follows:

Input test: through the PCB test board, give the corresponding effective mode of the input terminal of the tested BCM, and then the host computer sends and reads the corresponding input status to the tested BCM through the CAN bus, and the corresponding invalid mode also needs to be tested;

Output test: The upper computer sends corresponding message commands through the CAN bus to control the effective output of the tested BCM output, and then conducts the tested BCM output voltage test through the PCB test board;

Power supply: The power input of the BCM under test is provided by the program-controlled power supply for indirect testing;

Ground: given by the program-controlled power supply, indirect test;

CAN communication: indirect test;

LIN communication: Based on the fault code test, the board simulates the slave node of LIN, the host computer enables the LIN signal of BCM, and tests whether the slave node of LIN is lost through the message, and sends an error message to the host computer if it is lost.

Compared with the prior art, a kind of off-line detection equipment and testing method based on the CAN bus body controller product of the present invention has the following advantages:

The invention has strong versatility, adopts the design of PCB test board, does not use commercial test boards, can greatly reduce the cost of equipment construction, and the off-line testing equipment can be reused. During the testing process, testers do not need to participate in the operation. The sequence is programmed and modified according to product differences, and the test time is reduced. The input and output signals of the tested BCM are judged by the automatic test of the test equipment, which reduces human errors and improves the test accuracy.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

FIG. 1 is a schematic diagram of a switch circuit according to an embodiment of the present invention;

Fig. 2 is the schematic diagram of the acquisition circuit of the low effective switching quantity described in the embodiment of the present invention;

Fig. 3 is the schematic diagram of the highly effective switching quantity acquisition circuit described in the embodiment of the present invention;

4 is a schematic diagram of the principle of the test fixture described in the embodiment of the present invention;

Fig. 5 is a schematic diagram showing a visual interface of the upper computer software described in the embodiment of the present invention;

Fig. 6 is a schematic diagram illustrating the fixture testing process described in the embodiment of the present invention;

Fig. 7 is a schematic diagram of a CAN-bus-based vehicle body controller product off-line detection device and testing method according to an embodiment of the present invention.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The invention provides a CAN bus body controller product off-line detection equipment including the following components:

Programmable power supply, PCB test board, test fixture load box, CAN communication hardware tools, host computer, load module.

The programmable power supply is mainly for supplying power to PCB test boards, test fixtures and loads, and at the same time needs to control the power supply for the BCM under test.

The PCB test board adopts a product design similar to that of BCM. Based on the function of the single-chip microcomputer, the PCB test board is divided into digital input signal, digital output signal, CAN bus, LIN bus, PWM signal output signal, etc. The PCB test board is mainly for the tested BCM Validate the corresponding digital input signal, collect BCM output signal, enable analog signal input, CAN bus communication, enable PWM input signal, power input, etc.

PCB test board circuit design, the output signal adopts a general-purpose four-channel independently selected switch drive chip, which can realize digital high and low effective output, and provide high effective input signal and low effective input signal to the tested BCM, and at the same time at the switch end of the drive chip For the design of the peripheral circuit, the design of a variety of resistance circuits can be used to realize the series connection of different resistance values to the ground, to realize the output of different AD signals, to realize the test of different AD inputs of the tested BCM, and the tested BCM passes Read different AD values to judge whether the input channel is normal. The input signal adopts the extended input acquisition 151 chip, which can realize many input acquisitions, high and low effective acquisition of the output of the tested BCM, and the extended input channel can meet the generality test of the tested BCM.

The circuit is shown in Figure 1, U1 is a four-channel multi-function switch chip, the model is ADG1334, its working principle is that when the input INX level of a certain channel is high, the corresponding output channel DX and SXA are connected; when INX is low When level, DX and SXB are connected.

The connection relationship of the circuit is: the IN1 pin of U1 is grounded through the pull-down resistor R1, and connected to the control output pin CRT1 of the MCU, and CRT1 can pull IN1 to a high level. The S1A pin of U1 is connected to the VSS power supply, the D1 pin is connected to the board output pin OUT1, and the S1B pin is grounded; the VSS pin of U1 is connected to the system power supply VSS, and the GND pin is connected to the system ground GND; the S2B pin of U1 is connected to the system power supply VSS, D2 The pin is connected to the board output OUT2, and the IN2 pin is connected to the ground through the pull-down resistor R2, and connected to the control output pin CRT2 of the MCU, and CRT2 can pull IN1 to a high level; the IN3 pin of U1 is grounded through the pull-down resistor R3, and connected to The control output pin CRT3 of the MCU, CRT3 can pull IN1 to a high level; the S3A pin of U1 is grounded through the variable resistor R5, the D3 pin is connected to the board output pin OUT3, and the S3B pin is suspended; the VDD pin of U1 is connected to the MCU power supply VDD ; The IN4 pin of U1 is grounded through the pull-down resistor R4, and connected to the control output pin CRT4 of the MCU, and CRT4 can pull IN1 to a high level. The S4A pin of U1 is grounded through the variable resistor R6, the D4 pin is connected to the board output pin OUT4, and the S4B pin is suspended.

The working process is: OUT1 and OUT2 are used for the high/low effective switching value acquisition channel of the tested BCM; when CRT1 (or CRT2) outputs a high level, OUT1 (or OUT2) is connected to S1A (or S2A), and the output is high flat. When CRT1 (or CRT2) outputs low level or no output, IN1 (or IN2) pin is pulled down to low level by pull-down resistor R1 (or R2); OUT1 (or OUT2) and S1B (or S2B) are turned on, output low level. OUT3 and OUT4 are used to test the analog quantity acquisition channel of the BCM under test. When CRT3 (or CRT4) outputs a high level, OUT3 (or OUT4) is connected to S3A (or S4A), grounded through variable resistor R5 (or R6), and can be controlled by adjusting the resistance of R5 (or R6). Test of different analog acquisition channels of BCM; when CRT3 (or CRT4) outputs low level or no output, IN3 (or IN4) pin is pulled down to low level by pull-down resistor R3 (or R4); OUT3 (or OUT4) ) and S3B (or S4B) conduction, at this time OUT3 (or OUT4) has no output, which is equivalent to grounding through an infinite resistance. The tested BCM judges whether it is normal by reading different AD values.

The low effective switching value acquisition circuit is shown in Figure 2, which can be used for testing the low effective output circuit of the BCM under test.

The connection relationship is: L-IN is an effective low input signal, which corresponds to an effective low output signal of the BCM under test. The L-IN signal is connected to the system power supply VSS through the pull-up resistor R10, connected to the ground through the capacitor C1, C1 is used for signal filtering and anti-static; connected to the input of the expansion chip HC151 through the series resistor R11 and the parallel capacitor C2 to the ground pin HC151-DX.

The working process is: when the low effective output signal of the BCM under test has no output, the L-IN signal is pulled up to the power supply level VSS by the pull-up resistor R10; when the low effective output signal of the BCM under test has output, the L-IN The signal is pulled down to low level; the MCU reads the input signal level status through the expansion chip HC151, and compares it with the output status of the BCM to judge whether the BCM is working normally.

The high-effective switching value acquisition circuit is shown in Figure 3, which can be used for testing the high-effective output circuit of the BCM under test.

The connection relationship is: H-IN is an effective high input signal, which corresponds to the effective high output signal of the BCM under test. The H-IN signal is grounded through the filter capacitor C3 and the pull-down resistor R12. C3 is used for signal filtering and anti-static, and R12 is used to pull the H-IN signal to a low level when the BCM has no output; through the series resistor R13 and The ground parallel capacitor C2 is connected to the input pin HC151-DX of the expansion chip HC151.

The working process is: when the high effective output signal of the BCM under test has no output, the H-IN signal is pulled down to low level by the pull-down resistor R12; when the high effective output signal of the BCM under test has output, the H-IN signal is pulled up Pull it to high level; the MCU reads the input signal level status through the expansion chip HC151, and compares it with the output status of the BCM to judge whether the BCM is working normally.

The test fixture and load box are mainly used to simulate the state of the electrical appliances of the whole vehicle. The power consumption of the tested BCM after the output is effective is realized by connecting the power resistor in series. The fixture adopts a mechanical structure controlled by a solenoid valve to fix the tested BCM. Place the product for testing, and this part can be designed automatically through the cylinder solenoid valve.

The test fixture and load box adopt a common design. The load box is used to display the output of the corresponding BCM to be tested and replace it with a power resistor with the same parameters. It is led out with a rubber plug, so that it can be driven by an external load for verification; the test fixture is controlled by a solenoid valve, connected pneumatically, and combined with the structure of a photoelectric sensor and a metal contact switch to realize an automatic connection test for the BCM under test. For the specific test process, see Image 6.

The circuit of the test fixture adopts the working principle of the digital input and output control solenoid valve to realize the bodywork test of the tested BCM. The test fixture includes external relays, solenoid valves, indicator lights, metal contact switches, photoelectric sensors and other components. The metal contact switch and the photoelectric sensor detect that the BCM under test is placed in the test fixture, and the upper cover of the fixture is closed, and the result is fed back to the PCB test board. The output signal of the PCB test board is closed, and the external relay 1 is closed. After pushing up the cylinder, it is locked and the test starts. After the test is successful, the relay 2 is closed, the push-down cylinder is unlocked, and the green light flashes after the relay 4 is closed, the test is successful. If the test fails during the test, the relay 3 closes and the red light flashes. At this time, the red button needs to be pressed before the relay 4 can be closed, and the cylinder can be unlocked by pushing down. The schematic diagram is shown in Figure 4.

The design of the test fixture adopts a simple relay to control the mechanical mechanism of the solenoid valve to realize the process of uploading, testing, and downloading the tested BCM. The input signal collection and output control signals can be provided by the test PCB. The test process is simple and the control method is reliable. ,low cost.

CAN communication tools are mainly for the transmission of CAN bus signals and the sending and receiving of signal commands.

The upper computer software is developed based on .NET Freamwork, and the test cases of the BCM to be tested are written using C code. The upper computer sends test commands through the CAN bus control, and waits for the test feedback to judge the test results. The upper computer software interacts with the outside using USB- CAN device, the specific hardware can be Zhou Ligong or kvaser series CAN card.

The upper computer interface adopts a visual window design, which can realize manual debugging and automatic testing. Manual testing is divided into digital input, analog input, and digital output testing. The CAN sending function is called through the switch button to execute the test command of the BCM under test and control the BCM under test. Test the PCB board. The automated test is mainly to call the automated test script written by the lower computer code, automatically run the test program, and display the test result in the AutoTest messgae window, and automatically generate a test report in TXT format after the test is completed.

The upper computer software has a visual interface, which can be classified according to the test type of the tested BCM, and provides the user with an interface for the following functions: 1. CAN communication device initialization and transparent transmission test; 2. BCM low effective and high effective digital input test; 3 , BCM analog input test; 4, BCM digital output test.

The main functions of the upper computer in the test system are: 1. Connect the PCB test board through the CAN bus, and realize the control of the PCB test board and the tested BCM through the CAN information, thereby controlling the entire test process; 2. It can display the data on the bus in real time. CAN message and test details, record every test operation and result performed by the user, and save the result as a test log file in TXT format for reference.

The tested BCM needs to fill in the product test code, which mainly involves the bus signal transmission after the input signal is valid, the output is valid after receiving the valid output bus command, CAN receiving and sending signal processing, etc. This part of the processing is subsequently integrated into the product code to realize the information interaction test with the host computer software and the test board, so as to achieve the purpose of testing the BCM.

The testing process of the present invention is as follows:

The digital signal input test is divided into two parts: the tested BCM input valid and the tested BCM input valid command reading, as shown in Figure 7, the tested BCM digital input valid process is 1-3-5, the tested BCM digital input The effective command read flow is 1-7-6-2. During the test process, the test command transmission and judgment are always carried out through the CAN bus. The digital effective command of the tested BCM is executed through the test board, the valid state of the digital input of the tested BCM is sent by the tested BCM, and the final test result is carried out by the host computer. Judgment, to achieve a complete testing process.

First, the host computer sends the BCM input test command to the PCB test board through the CAN bus. After the PCB test board receives the test BCM input command, the corresponding channel outputs a high-low valid signal to the tested BCM. At this time, the digital input of the tested BCM is valid; then After a delay of 200ms, the upper computer sends the corresponding hardware channel digital input test command to the tested BCM through the CAN bus. At this time, the tested BCM can send the input status of the corresponding channel of the BCM to the upper computer through the CAN bus according to the code added before; Finally, the upper computer judges after receiving the input status signal of the BCM under test. If it is a valid command, the test is successful, and if it is an invalid command, the test fails.

The analog input signal test is similar to the digital input signal test. The difference is that the hardware is changed on the test board. Compared with the 12V high effective of the digital input signal and the low effective of the ground wire, the analog input signal is connected with different resistance values. After the resistance of the tested BCM analog input circuit is divided, the tested BCM single chip microcomputer analog input collects different AD values to realize that the analog input is valid. The test process is 1-3-5, and the tested BCM obtains the corresponding The command reading process after analog input is 1-7-6-2.

First, the host computer sends the BCM analog input to the PCB test board through the CAN bus, and the PCB test board controls the resistors of different resistances through the chip to connect with the tested BCM to the ground wire, so that different AD analog signals are valid; then delay 200ms, The upper computer sends an analog input test command corresponding to the number of channels to the BCM under test through the CAN bus, and the BCM under test sends the AD value of the analog signal collected by the test to the upper computer through the bus; finally, the upper computer performs the test according to the AD value sent by the BCM under test. Judgment, if the AD value is within the range of the valid command, the test is successful, if the feedback AD value is not within the range, the test fails.

The digital output signal test is divided into two parts: the output valid of the tested BCM and the interpretation of the valid output command. As shown in the diagram 1, the tested BCM output valid process is 1-7-8-9, and the tested BCM output detection command process is 1- 3-4-2. During the test, the host computer first sends a test command to make the output of the tested BCM valid, and then sends it to the PCB test board through the bus to collect the BCM output signal of the corresponding channel. The CAN signal is used to judge the test result and complete the output test process of the BCM.

First, the host computer sends a test digital output signal command to the tested BCM through the CAN bus. After the tested BCM receives the bus signal, the corresponding output channel is enabled, the high effective output is 12V, and the low effective output is grounded. The test of the digital output signal requires The external fixture is used for the test, and the output of the BCM under test needs to be connected in series with a power resistor; then, after a delay of 200ms, the host computer sends the corresponding channel output test command to the PCB test board, and the internal input acquisition circuit of the PCB test board will be tested after the output signal of the BCM is collected. , and send it to the host computer through the CAN bus signal; finally, the host computer judges according to the CAN signal sent by the test board, and the tested BCM output valid test is successful. If the BCM output valid command is not received, the test fails.

PWM signal input test, the PWM signal input test is similar to the digital input, the specific pin of the microcontroller in the test board is used as the PWM output port, the software clock comparator is set, and a certain frequency PWM waveform is output to meet the effective mode of the PWM signal of the tested BCM ;The test process is still initiated by the host computer. First, it sends a PWM input signal test command to the test board. After the test board receives the CAN bus command, the corresponding microcontroller pin outputs the PWM waveform to the tested BCM, and then the tested BCM receives the PWM. After the waveform is generated, the effective method will be sent to the host computer via the CAN bus, and the host computer will judge whether the test is successful or not based on the bus signal sent by the tested BCM.

LIN bus signal test, for the test of LIN bus signal, integrate the LIN module in the test board, as the slave node of the tested BCM to test the LIN signal. First, the upper computer sends a test LIN signal command to the test board through the CAN bus, and the corresponding LIN signal is enabled after the test board receives the command; then, after a delay of 200ms, the upper computer sends a test LIN communication command to the tested BCM, and the BCM The master node makes a LIN signal request and sends it to the test board, and the BCM sends a CAN bus message to the host computer whether the LIN slave node is lost; finally, the host computer judges according to the CAN bus signal sent by the BCM. If it is judged that the slave node is not lost, Then the test is successful.

During the entire testing process of BCM off-line testing equipment, the automated test sequence has been written according to the hardware schematic diagram of BCM and the definition of PIN pins. During the testing process, the upper computer test interface can be programmed with CAPL to send CAN signal instructions and send rules It can be carried out according to the rules of the component manufacturer, and the CAN signal receives the command to judge. During the test, the test result of a certain test sequence can be recorded. After the test is completed, the test result can be saved in TXT format to generate a test report. . The test result can be fed back through the PCB test board. If the test is successful, the control fixture will automatically pop open the tested BCM and prompt that the test is successful. If the test fails, you need to manually open the test fixture and replace the BCM for the following test.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1. The utility model provides a based on CAN bus automobile body controller product check out test set that rolls off production line which characterized in that: the test device comprises a program control power supply, a PCB test board, a test fixture, a load box, a CAN communication tool, an upper computer and a load module;

the program control power supply is used for supplying power to the PCB test board, the test fixture and the load box and controlling the power supply of the tested BCM;

the PCB test board is used for carrying out validation of corresponding digital input signals, collection of BCM output signals, validation of analog signal input, CAN bus communication, validation of PWM input signals and power supply input on a tested BCM;

the test fixture and the load box are used for simulating the state of the electric appliance of the whole vehicle and realizing the power consumption of the tested BCM after the output of the tested BCM is effective by connecting power resistors in series;

the CAN communication tool is used for transmitting CAN bus signals and sending and receiving signal commands;

and the upper computer sends a test command through the CAN bus control and waits for test feedback to judge a test result.

2. The CAN bus-based vehicle body controller product offline detection device of claim 1, wherein: the PCB test board output signal adopts a universal four-channel independently selected switch driving chip for realizing digital high-low effective output, and provides high-effective input signals and low-effective input signals for a tested BCM, meanwhile, a plurality of resistor circuits are designed at the switch end of the driving chip, so that different resistor values are connected to the ground in series, the output of different AD signals is realized, the test of different AD inputs of the tested BCM is realized, the tested BCM judges whether the input channel is normal by reading different AD values, the input signal adopts an extended input acquisition 151 chip, a plurality of input acquisitions can be realized, the high-low effective acquisition is carried out on the output of the tested BCM, and the extended input channel meets the universality test of the tested BCM.

3. The CAN bus-based vehicle body controller product offline detection device of claim 2, wherein: the PCB circuit comprises a switch circuit, a low effective switching value acquisition circuit and a high effective switching value acquisition circuit.

4. The CAN bus based vehicle body controller product offline detection device of claim 3, wherein: the switch circuit comprises a channel multifunctional switch chip U1, wherein an IN1 pin of U1 is grounded through a pull-down resistor R1 and is connected to a control output pin CRT1 of the MCU, the IN1 can be pulled to be at a high level by the CRT1, an S1A pin of U1 is connected with a VSS power supply, a D1 pin is connected with a card output pin OUT1, and an S1B pin is grounded; a VSS pin of the U1 is connected with a system power supply VSS, and a GND pin is connected with a system ground GND; the S2B pin of U1 is connected with system power VSS, the D2 pin is connected with a board card output OUT2, the IN2 pin is connected to the ground through a pull-down resistor R2 and is connected to a control output pin CRT2 of the MCU, and the CRT2 can pull the IN1 to a high level; an IN3 pin of U1 is grounded through a pull-down resistor R3 and is connected to a control output pin CRT3 of the MCU, and the CRT3 can pull IN1 to be high level; the pin S3A of the U1 is grounded through a variable resistor R5, the pin D3 is connected with a card output pin OUT3, and the pin S3B is suspended; the VDD pin of the U1 is connected with the MCU power supply VDD; an IN4 pin of the U1 is grounded through a pull-down resistor R4 and is connected to a control output pin CRT4 of the MCU, the CRT4 can pull an IN1 to be high level, an S4A pin of the U1 is grounded through a variable resistor R6, a D4 pin is connected with a card output pin OUT4, and an S4B pin is suspended.

5. The CAN bus based vehicle body controller product offline detection device of claim 3, wherein: the low effective switching value acquisition circuit is used for testing a low effective output circuit of the tested BCM, L-IN is a low effective input signal and corresponds to a low effective output signal of the tested BCM, the L-IN signal is connected to a system power supply VSS through a pull-up resistor R10 and is connected to the ground through a capacitor C1, and C1 is used for signal filtering and anti-static; is connected to the input pins HC151-DX of the expansion chip HC151 through the series resistor R11 and the ground parallel capacitor C2.

6. The CAN bus based vehicle body controller product offline detection device of claim 3, wherein: the high-effective switching value acquisition is used for testing a high-effective output circuit of a tested BCM, H-IN is a high-effective input signal and corresponds to the high-effective output signal of the tested BCM, the H-IN signal is grounded through a filter capacitor C3 and a pull-down resistor R12, C3 is used for signal filtering and static electricity prevention, and R12 is used for pulling down the H-IN signal to a low level when the BCM is not output; is connected to the input pins HC151-DX of the expansion chip HC151 through the series resistor R13 and the ground parallel capacitor C2.

7. The CAN bus-based vehicle body controller product offline detection device of claim 1, wherein: the test fixture adopts a mechanical structure of a relay control electromagnetic valve, and is used for automatically connecting and testing the tested BCM, and comprises an external relay, an electromagnetic valve, an indicator lamp, a metal contact switch and a photoelectric sensor.

8. The CAN bus-based vehicle body controller product offline detection device of claim 1, wherein: the interface of the upper computer adopts a visual window design, manual debugging and automatic testing are realized, manual testing is divided into digital input, analog input and digital output testing, a CAN sending function is called through a switch button to carry out a testing command of a BCM to be tested, and the BCM to be tested and a PCB board card to be tested are controlled.

9. The test method for the offline detection equipment based on the CAN bus automobile body controller product is characterized by comprising the following steps: the method comprises the following detection processes:

inputting and testing: a PCB test board gives a corresponding effective mode to the input end of the BCM to be tested, then the upper computer sends and reads a corresponding input state to the BCM to be tested through a CAN bus, and the corresponding ineffective mode also needs to be tested;

and (3) output test: the upper computer sends a corresponding message instruction through the CAN bus to control the effective output of the tested BCM, and then the tested BCM output voltage is tested through the PCB test board;

power supply: the power supply input of the BCM to be tested is provided by a program control power supply for indirect testing;

ground: the test is performed indirectly through the program control power supply;

CAN communication: indirect testing;

LIN communication: based on fault code testing, the board card simulates an LIN slave node, an upper computer enables an LIN signal of a BCM, whether the LIN slave node is lost or not is detected through a message, and the loss sends an error message to the upper computer.