How to judge the quality of proximity switch

　　How to judge the quality of proximity switch

　　Connect the power supply according to the instructions, use a matching induction source to approach the switch over a long distance, and use the voltage range of the multimeter to detect whether the out line and the vcc line have signal output or whether the signal changes. Because the proximity switch is divided into pnp and npn types, the signal output is different. There are three wires, two power supplies and one signal output. Some are high effective outputs, and some are low effective outputs. Use a multimeter to measure the output voltage to see if there is any difference when there is a signal or no signal output.

　　The most direct way to judge whether a proximity switch is good or bad is to power on the test, that is, add the corresponding voltage to the power supply end, use a metal object close to the switch sensing area, and then use a multimeter or dummy load to test to see if the switch is normal. Of course, some proximity switches have working indicator lights, which can intuitively show the working status of the proximity switch.

　　NPN type normally open: brown wire connected to +5V (voltage is subject to the example mark), blue to the negative pole and the black line of the multimeter, black to the red line of the multimeter (the multimeter is first switched to the DC voltage 20V range), at this time it should be +5V, when a metal object (depending on the proximity switch) is placed close to the proximity switch, the multimeter should be 0V, this proximity switch is normal. NPN type normally closed, the voltage display is the opposite.

　　The wiring is different when measuring PNP and NPN types. The red line of the multimeter is connected to the brown line, and the black line is connected to the black line of the proximity switch. When approaching and leaving, the voltage displayed on the multimeter is 5V and 0V, which is normal, otherwise it is damaged.

　　Sometimes, the proximity switch is not disassembled, such as on the equipment, how to judge whether the proximity switch is good or bad? In fact, it is also very simple. The device is on the equipment, so there is a normal voltage provided to the proximity switch. Connect the positive and negative of the power supply, open the output end, use the voltage range of the multimeter, test the output voltage value of the proximity switch, and record it. Use the metal proximity switch sensing area to see the voltage change. For example, if the power supply voltage is 24V, then the output end should change between 24V and 0V. When the metal is close to and not close to the object, the output voltage should change. If there is no change, it means that the proximity switch is broken. The output of PNP and NPN is opposite.