How to use a multimeter to measure a proximity switch
The proximity switch can be measured with a multimeter; The measurement method is also very simple, just treat it as a switch.
So, let's learn what this proximity switch is exactly.
A proximity switch, as the name suggests, is a switch that only works when it is "close". The proximity switch should be classified as a position switch, and the biggest difference from our common travel switch is that the proximity switch can complete the position measurement work without touching the measuring object.
In short, the essence of proximity switches is still switches, but the working principle of this switch is different. Currently, common proximity switches on the market can be roughly divided into the following categories:
Photoelectric proximity switch: Through the reflection of light, when there is an obstacle blocking the emitted light, the device will generate an on or off signal.
Hall type proximity switch: You may not be familiar with the word Hall yet. In fact, Hall is a form of circuit that is sensitive to magnetic substances. When a magnetic object is detected, the circuit will change and output the corresponding on/off signal through a conversion circuit
Capacitive proximity switch: When it comes to capacitive switches, we need to understand the issue of dielectric constant. When an object passes between the two plates of a capacitor, the dielectric constant changes, generating a signal that is then converted and output through a circuit.
How to use a multimeter to measure proximity switches?
Although it is also a switch, the measurement of this proximity switch is somewhat special. If we measure it directly, we will definitely not be able to measure anything because this proximity switch requires power supply during normal operation, just like an electrical appliance that needs to be connected to a power source, and most of them are 24V DC.
After supplying power to the proximity switch, we also need to understand its internal wiring method. Taking the three wire proximity switch as an example, friends who understand some circuit knowledge can easily see that the on-off of the proximity switch is related to a transistor. When the main circuit of the proximity switch senses an object, it will cause an on-off change inside the circuit. This will form a closed circuit at both ends of the load in the figure, that is, a 24V power supply is added to both sides of the load. This is actually the working principle of the proximity switch.
