How to test a photoelectric switch's normally open and normally closed positions with a multimeter
Photoelectric switch (photoelectric sensor) is the abbreviation of photoelectric proximity switch. It uses the blocking or reflection of the light beam by the detected object, and the synchronous circuit gates the circuit to detect the presence or absence of the object. Objects are not limited to metals, all objects that can reflect light can be detected. The photoelectric switch converts the input current into a light signal on the transmitter and emits it, and the receiver detects the target object according to the intensity or presence of the received light. The common photoelectric switch smoke alarm in the security system is often used in the industry to count the number of movements of the mechanical arm.
Nowadays, many photoelectric switches have both normally open and normally closed outputs. Normally open and normally closed are the output states of the photoelectric switch when no object is sensed. It means that the photoelectric switch has a normally open output and a normally closed output when there is no action.
Distinguish whether the photoelectric switch is normally open or normally closed:
1. The single contact can be distinguished from the model parameters;
2. Many products provide two sets of normally open and normally closed contacts at the same time, you can see the logo on the switch;
3. You can use a multimeter to measure
How to use a multimeter to judge whether the proximity switch is normally closed or normally open 1 . Three-wire DC24V inductive PNP type: brown connects to +24V, blue connects to 0V.
The black is connected to the red test lead of the DC voltage range of the digital multimeter, and the black test lead is connected to 0V.
At this time, the multimeter is normally closed with 24V voltage, and normally open without 24V voltage.
2 . Three-wire DC24V inductive NPN type: brown connects to +24V, blue connects to 0V.
Black Connect to the black test lead of the DC voltage range of the digital multimeter, and the red test lead to +24V.
At this time, the multimeter is normally closed when there is 24V voltage, and it is normally open when there is no 24V voltage.
How to measure photoelectric switch normally open
1. The single contact can be distinguished from the model parameters;
2. Many products provide two sets of normally open and normally closed contacts at the same time, you can see the logo on the switch
3. You can use a multimeter to measure
