Multimeter how to measure the normally open point and normally closed point of the photoelectric switch
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.
Points 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 see the logo on the switch;
3, you can use a multimeter to measure
Proximity switch is 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!
When using the multimeter to check the normally open and normally closed points, the multimeter should be adjusted to a voltmeter first to check whether there is voltage in the line accessing the contacts, and then check the normally open and normally closed contacts.
1. connect the two pens of the voltmeter to the two ends of the normally open point, if there is no voltage, the multimeter will be adjusted to the ohm file, the two pens are connected to the two ends of the contact, the multimeter is displayed as 0, it is a normally open contact, and if there is data on the multimeter, which is about 0.1-1 Ω, then it is a normally closed contact
2. If there is a voltage, it can be concluded that the contacts for the normally open point, at this time it is also prohibited to adjust the ohm gear to check, because adjusting the ohm gear, the two pens access, the multimeter is equivalent to a wire, which is equivalent to the normally open point of a short-circuit, so that the normally open into a normally closed, which may burn out the multimeter, and even on-site devices that line conduction, resulting in inestimable dangers!
