1. Single contact ones 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

1 . Three-wire DC24V inductive PNP type: Brown is connected to +24V, blue is connected to 0V.

The black test lead 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 when there is 24V voltage, but it is normally open when there is no 24V voltage.

2 . Three-wire DC24V inductive NPN type: Brown is connected to +24V, blue is connected to 0V.

Black is connected to the black test lead of the DC voltage range of the digital multimeter, and the red test lead is connected 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.