Application of LABWINDOWS in the detection of automobile electronic fuel injection module

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Application of LABWINDOWS in the detection of automobile electronic fuel injection module [Copy link]

Editor's note: This article introduces how to complete the hardware test of the input/output port of the automotive electronic fuel injection module (EFI) and save the test data to a TXT file by using the LABWINDOWS software and corresponding hardware facilities (NI-5112, PXI-8156B, NI-5411, PXI-6070E, NI-2503) of the American NI company. At the same time, the functional test of the module under the set working conditions is completed through programming, thereby ensuring the reliability of the product.
Introduction
The EFI module test system consists of five parts: NI tester, simulated load box, power supply, barcode scanner and test fixture. After the tester manually puts the module into the fixture and scans the barcode, the system will automatically perform multiple tests such as module power consumption, input terminal resistance to ground, A/D sampling value, output terminal leakage current, FET clamping voltage, E2PROM verification, etc. At the same time, the test data and pass/fail status are recorded, and the data is automatically stored as a TXT file for future data analysis.

Figure 1 Hardware structure of EFI test system

Hardware Structure
The hardware structure of the EFI test system is shown in Figure 1. The module detection includes three parts: input port hardware, output port hardware and function detection under specific working conditions. To complete the hardware detection of the input port, we selected the PXI-6070E multifunction card for data acquisition. It has 64 12-bit analog inputs, 2 analog outputs, and eight digital I/0 ports. The port switch uses the NI-2503 switch card, which is a two-line 24-bit switch card responsible for connecting the tested port to the acquisition card PXI-6070E.
Similarly, the hardware switching of the output end is completed by another NI-2503 card. Data acquisition is completed using the NI-5112 oscilloscope card. Its 100MHz bandwidth can ensure the acquisition of ignition and injection pulses, and the collected data will be placed in the specified buffer. By performing data analysis, we can get the maximum value and frequency value of the output signal pulse. After completing the hardware detection
, the BOOTSTRAP mode is also used to send the calibration data to the module E2PROM, and then the chip is switched to single-chip mode. Simulate normal working conditions to detect the working status of the module, and then complete the functional test under specific working conditions. Through the above tests, the reliability of the module is ensured.

Software Design
In an environment with a computer and corresponding hardware card, LABWINDOWS, with its C language-based development environment, good user interface (as shown in Figure 2), powerful library functions and convenient and fast debugging methods, enables designers to design, debug and develop actual test systems at the fastest speed, greatly reducing the workload.
The module detection system software can work in three modes: hardware diagnosis mode; functional test mode; EOL test mode.

Figure 2 LABWINDOWS good user interface

The hardware detection of the input port can be easily completed by calling the driver functions of NI-2503, NI-5112 and PXI-6070E.
The hardware detection of the chip's A/D sampling value and output port requires downloading a special test program (written in assembly language, about 1KB). Using software programming, you must first enter the BOOTSTRAP mode of 68HC11, and then download the special test program to the chip. By calling the subroutines of the special test program, you can complete multiple functions including reading/writing chip RAM, E2PROM area, checking RAM, E2PROM area, reading A/D sampling values, setting PWM output pulses, and checking version numbers.
During the functional test, the chip is operated in single-chip mode, and the 60-2 waveform of the speed signal is simulated by calling the NI-5411 arbitrary waveform generator driver function. At the same time, the corresponding voltage signal is input to simulate the signal input of each sensor to complete the functional test under specific working conditions.
All test results will be stored in the specified file for statistical CPK and data analysis.

Analysis and Evaluation
Through the above practical applications, the test system developed using LABWINDOWS software has the following significant advantages:
1. Accelerates the system development cycle and reduces the development difficulty. Using LABWINDOWS, you can easily call hardware drivers and functions, reduce the workload, and accelerate the development process.
2. Reduces the test cycle. Using LABWINDOWS, the data transmission speed and measurement time are improved, and the measurement time of the product is reduced. The measurement time of each module is less than 50s.
3. It has high versatility. Using the same hardware environment, only fine-tuning the software can measure ECS, DIS and other series of products.