Multimeter for measurement of the normally open and normally closed points of light barriers
Photoelectric switch (photoelectric sensor) is the abbreviation of photoelectric proximity switch, it is the use of the detected object on the light beam blocking or reflecting, by the synchronous circuit selective circuit, so as to detect the presence or absence of the object. Objects are not limited to metal, all objects that can reflect light can be detected. Photoelectric switch will be input current in the transmitter converted to light signals shot, the receiver and then according to the strength of the received light or the presence or absence of the target object detection. Security systems in the common photoelectric switch smoke alarms, industry often use it to count the number of movements of the mechanical arm.
Now a lot of photoelectric open light that is normally open and normally closed output. Normally open and normally closed is the output state of the photoelectric switch in the absence of sensing the object. Means that the photoelectric switch in the absence of action has a normally open output and normally closed output.
Distinguish photoelectric switch is normally open or normally closed: 1, single contact can be distinguished from the model parameters; 2, many products at the same time to provide normally open and normally closed two sets of contacts, you can look at the logo on the switch; 3, you can use a multimeter for measurement!
How to use a multimeter to determine whether the proximity switch is normally closed or normally open?
Is the proximity switch normally closed or normally open?
1 . Three-wire DC24V inductive PNP type: brown to +24V, blue to 0V.
Black DC voltage digital multimeter connected to the red pen, black pen connected to 0V.
At this time the multimeter has 24V voltage is normally closed, no 24 volts is normally open.
2 . Three-wire DC24V inductive NPN type: brown to +24V, blue to 0V.
Black DC voltage digital multimeter connected to the black pen, red pen connected to +24V.
At this time the multimeter has 24V voltage is normally closed, no 24 volts is normally open!
