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1.1 The main hardware for producing automotive wiring harness
Programmable controllers (PLCs), pneumatic clamps, machines that use air to compress, corresponding electromagnetic reversing valves, and more. For the selection of pneumatic fixtures, since the system studied in this paper is to test eight or nine products, the most cost-effective product should be selected according to the characteristics of the test object when selecting the pneumatic fixture; for the electromagnetic directional valve, due to its The main function is the control of the cylinder's movements, so when selecting the product, we must fully consider the factors such as quality, volume, and lifespan. After the analysis, the selected product also needs two workloads, after comparison of various products. Finally, we chose the 4 V 110.06 directional solenoid valve and the AFR 1500 pneumatic two-piece.
1.2 Hardware Design and Basic Operation
The system formed by the hardware circuit needs to carry out two basic tests of on-off and insulation resistance. For the on-off detection, the main items to be tested include open circuit, misalignment, short circuit, and poor contact. For the insulation, the detection is mainly the insulation between the wire harness and the wire harness and the connector. Therefore, the following tasks are mainly performed when testing. The PLC needs to be set accurately, and the functions it has in the entire system detection include providing information for detection, signals expressed by the switch, and detection results. Corresponding to the setting of PLC port: Output: Y000-Y007 and Y010-Y020 can be output simultaneously; Y033 port is connected to buzzer; Y040-Y043 port is connected to solenoid valve 1-4; for input in X000-X007 and The point-by-point input mode is adopted in the X010-X020 interface; the limit switch 1-4 is connected to the X040-X043 port; the start button is connected to the X404 port. Each port of the PLC should be connected with wires to ensure that the wire harness can form a reliable loop with the input and output ports, and then analyze the detected conditions through the signal phenomenon.
2, the system's software structure
The software of the system is mainly designed from the PC and the PLC. The main function of the PC is to send and receive data, and compare the acquired data with the data in the built database to determine the location of the fault and pass the monitor. The result of the judgment is displayed in real time. PLC uses GxDeveloper software, which has powerful functions to meet the development and programming environment of multiple products. In addition, this software can also implement online debugging, change and monitoring procedures. PLC is the most important core part of the harness detection system. It must not only be able to reliably detect all harnesses, but also need to process the acquired data in real time in order to determine the operating status of the system. The basic steps of detection are briefly described below:
In the detection of the wire harness, the power should be turned on first to ensure that the system is in a waiting state. At this time, the green light on the hardware circuit flashes. After the green light is shining, put the wire harness into the designed system and insert it into the positioning slot. The thin air cylinder clamps the wire harness, starts the inspection, and performs the storage processing on the obtained result. After the harness detection is completed, the cylinder is released and the harness is removed. At this time, the PC compares the results obtained from the inspection. If the green indicator is on, it indicates that the harness is not faulty, otherwise it indicates that the harness is faulty.
