What is the wiring method of the detection switch?
Release time：2019-09-06 Clicks： Click
What is the wiring method of the detection switch, and how to wiring in detail, the following gives you a detailed introduction, please have a look.
Most of the commonly used detection switches are cylindrical. Generally speaking, the thicker the diameter, the farther the detection distance is. According to the different detection objects, the detection switch can be divided into inductance and capacitance. The inductance detection switch detects the change of magnetic field by Hall effect. Because the solid can cause the change of magnetic field, the inductance detection switch mainly detects the solid, mainly steel.
Capacitance detection switch is essentially a plate of capacitance. When the detected object approaches, the dielectric constant of the whole capacitance changes. Therefore, it is considered that there is an object close. Therefore, capacitance detection switch can detect both solid and non-solid, but usually we use inductance detection switch to detect solid. So we all default capacitive detection switch to detect non-solid. For example, ceramics, paper, wood and so on.
The practical application of the detection switch in the industrial field, it is usually fixed by the bracket, when the detection object is close, its indicator light will be on, indicating that the detection switch has output, similarly, if the connection is correct, the PLC will have input signal. How does the detection switch access the input point of the PLC? In fact, it is similar to the button switch. Usually the detection switch has three wires, namely brown, blue and black. Brown and blue are power sources, usually 24 V in brown and 0 V in blue. Black is the signal line, which receives the input of PLC, and this signal is exactly what we need.
What should we do if we want to connect the signal of the detection switch to the input point I0, which is the yellow fluorescent pen part? In fact, it's very simple. Look at the red circle part, the PLC has provided us with the output power. We just need to connect the three wires of the detection switch in turn.
This is the actual wiring of the PLC. The yellow fluorescent pen marks the three wiring of the detection switch. Brown and blue are connected to the 24V and 0V of the PLC respectively, and black is connected to the I0. When an object reaches the sensing distance of the detection switch, the I0 of the PLC will be input, and we can do the processing in the program. It should be noted that the 0V and COM0 connections in the figure are short, so this connection method is suitable for PNP type detection switch. The NPN type detection switch according to this connection, there will be no signal. The connection of the detection switch has nothing to do with NPN, PNP type and sensory capacitance.
Another point to note is that the detection switch should be directly connected to the input of the PLC, without adding any form of relay and other conversion devices.