How to use a multimeter to measure proximity switches
The proximity switch can be measured using a multimeter; The measurement method is also very simple, just treat it as a switch.
So, let's understand what this proximity switch really is.
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 switches 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 their working principles are different. Currently, common proximity switches on the market are 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: People may not be familiar with the term Hall, but 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 through the conversion circuit, the corresponding on or off signal will be output:
Capacitive proximity switch: When it comes to capacitive proximity switches, it is important to understand the issue of dielectric constant. When an object passes between the two electrode plates of a capacitor, the dielectric constant changes, which generates 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, which needs to be connected to a power source. Most of them are DC 24V, which is a three-wire wiring method.
So, connecting the power to the proximity switch is the first step in the measurement.
After supplying power to the proximity switch, we also need to understand its internal wiring method. Let's take the three-wire proximity switch as an example. Friends who know some circuit knowledge can easily see that the on-off of the proximity switch is related to a transistor. When an object is sensed in the main circuit of the proximity switch, the on-off change inside the circuit will occur, which will form a closed circuit at both ends of the load in the figure below, That is, a 24V power supply is added to both sides of the load, which is actually the working principle of the proximity switch.
When we use a multimeter to measure the voltage on both sides of the load, we can determine whether the proximity switch is on or off.
Please note that due to the different forms of proximity switches, it is not certain whether the load end shares the positive or negative pole with the power supply. Actual measurements should be made according to our product manual.
