How to directly detect proximity switch with multimeter?
Proximity switches are divided into two wires and three wires. Let's explain it separately below.
First of all, it is three-wire, and three-wire proximity switches are widely used. The output is divided into NPN and PNP. The three-wire proximity switch needs extra power supply to work, so it should be powered on before measurement. Generally, the wiring is 12-24VDC in brown, 0V in blue and signal output in black. We connect the wires and power on, put things in front of the proximity switch and get as close as possible. If the proximity switch detects an object, its output indicator light will light up. There is a premise that you need to know what this proximity switch detects. If you don't know, you can try more objects, such as metals and magnets. If all these have been tried and the indicator light is not on, then you can use a multimeter to measure. No matter what kind of proximity switch he is, just measure the signal line and the voltage of 24V or 0V to see if there is any voltage. If there is no voltage, it means that the proximity switch is broken. If the indicator light is on, it is good, so there is no need to measure.
Followed by two-wire, two-wire proximity switch does not need additional power, but it is also divided into two connections. The measurement method is basically the same as that of the third line. The colors of the two lines are usually brown and blue. The first connection is that the blue wire is connected to 0V, and the brown wire is connected to the signal. Or use an object to approach the proximity switch. If the proximity switch is good, the indicator light will be on. If it is not, it can be measured with a multimeter. Measure whether there is voltage between the signal line and 24V voltage. Nothing is bad. Another connection and measurement is just the opposite.
