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NPN/PNP output of sensor
what is the difference between npn and pnp output in a sensor?

dear all,
good morning!
new in here.
i have a question.
what is the difference between npn and pnp output in a sensor?
do they have any differences or advantages in application?
there is also other type of output which is VOLTAGE, is this output is same as PNP output?
please help me, i'm a bit confused.

many thanks,

PNP is the European and American standard.
NPN is used in the East (Japan,Taiwan,etc.).
In PNP the common is 0V, in NPN is 24V.
NPN is faster and easier to implement.
Voltage may be an analog out.

By Meir Saggie on 3 June, 2004 - 10:47 pm

A perfect example of confusing terminology - tells how the function was implemented instead of how it works for you. NPN and PNP are two transistor types - the device that switches your load ON or OFF.
If you supply is say, 24 VDC, then:
If the sensor ends in an NPN transistor, your load is placed between the sensor output (NPN transistor collector) and the positive (+24VDC) side of the supply.

If the sensor ends in a PNP transistor, your load is placed between the sensor output (PNP transistor collector) and the negative (-24VDC) side of the supply.


By Matthew Hyatt on 4 June, 2004 - 12:47 am

John, pick up a book on transistor theory or take a basic electronics course.


By William Hinton Sr. Electrical Engineer @ Delphi on 4 June, 2004 - 12:58 am


NPN output devices connect to SINKING inputs (pull the voltage down to show a logic 1) and PNP output devices connect to SOURCING inputs (raise the voltage high to show a logic 1). Generally you simply use the type of output device that matches up with your input device.

I hope this helps

Take the last two letters is easiest way to define.
i.e. NPN = PN 24v(P) dropping to 0v(N) when outputting
PNP = NP 0v(N) rising to 24v(P) when outputting.

That is the way I remember it anyway.

By Anonymous on 20 July, 2004 - 7:48 pm

Sorry. I don't understan.
i think NPN type sensor = load connected "+"
PNP type sensor = load connected "-"
i don't english very well..^^
i'm Korean
Good luck to you~!

By Aditya Kulkarni on 22 July, 2004 - 12:14 am

if u r sinking current from the field use PNP devices use NPN if u r doing the opp. PNP = +24V Dc NPN = -24V DC (eg).

By Matthew Hyatt on 4 June, 2004 - 5:59 pm

You should take a basic course in transistors and electronics.


By Staf Van Gestel on 15 September, 2004 - 5:43 pm

You find documentation with schematics on (under proximity switch) and indeed what the others told you is correct. But I think the voltage is just the Power input for the sensor. Another thing is that the if the NPN-type is used, that your 'load' is not working when it is not activated by the sensor. Because it is connected with the +V of the power supply it is possible that, when there is a leak to the earth that your load is working when it is nog supposed to. And this situation can be dangerous.