Which is more popular NPN or PNP sensors

Excalibur

Member
Join Date
Mar 2003
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1
Doing a little quick research/info gathering. The opinion is that NPN is more popular in the US and PNP is more widely used in Europe.
Would you agree or disagree with this statement.
Thanks
 
npn ver pnp

i don't have any facts but...

the people i work with have a hard time working with
npn... a mind set on polarity i guess...

i prefer pnp but am comfortable with either..
 
PNP, NPN, Sink or Source this really can confuse many people. I tend to go for PNP when doing a project from start to completion.The Asians seem to favour NPN from what I have seen in the printing industry whereas the Germans and the Fins tend to go for PNP, again this is only what I have come across through installing or servicing machinery from these countries.
 
Terry Woods, one of the true professionals that is a member of this site offered a very good description of NPN and PNP devices. You can view it here:> http://www.patchn.com/npnpnp.htm

I look at it this way:
NPN negative postive negative a negative ouptut from device
sinking sinking in a boat or going down ..ie negative

PNP positive negative positive positive output from device
sourcing provide the voltage..the source...ie positive

I understand the reasoning for using NPN (which is common in the US. Using NPN means there is NO voltage applied to devices therefore the less likelihood of any form of shock. A low DC voltage either way probably would not shock anyone but its even less likely using the common side especially if its not a floating common.
 
NPN, PNP Sensors

I agree, Terry gave a very good example.

In a sinking configuration, current passes through the load first, through the output switch of the sensor second and lastly to ground. A sensor with a sinking output switches the ground, or negative, leg of the circuit.
In contrast, sourcing refers to a configuration in which the sensor is the source of the current required to power the load. In a sourcing situation, current supplied by the sensor passes through the load second and then to ground. A sensor with a sourcing output switches the positive leg

According to Gem sensor publication;
Sinking, the more widely used of the two, involves the switching of load current (power) supplied by a power source external to the sensor. In a sinking configuration, current passes through the load first, through the output switch of the sensor.

Even though my most common use is Sourcing.

There's something else you can do with NPN and PNP transistors. If a circuit only contains one type, you can replace it with the other type, providing you reverse the polarity of the supply.

Roger
 
Last edited:
There's something else you can do with NPN and PNP transistors. If a circuit only contains one type, you can replace it with the other type, providing you reverse the polarity of the supply.

Not all devices will allow reversing of polarity BUT there are ways to use an NPN device for a PNP and vice versa.

Checkout this blast from the past:
http://www.plcs.net/dcforum/DCForumID1/1974.html
 
This information you can use in the robot controller too

NPN..PNP...SINK..SOURCE..
You can apply this knowledge into Robot's controller too.
The Explanation from Prof.Terry Woods and the earlier answer quite
clear.
I post this if you want to work with PLC+Robot

Platootod
:p

sink source.jpg
 
When integrated circuits were first introduced, open-collector outputs became the defacto-standard and were used almost exclusively until a means was later found to add resistor pullups and then totem-pole outputs to an IC..... Even to day, the most common IC components used in interfacing are still open-collector, and employ single or darlington paired npn transistors....... Take a look at any I/O card, and you're likely to find a mitt full of opto-couplers scattered across the pcb...... Try to spec out such couplers for DC use such as the common 4n26 or 4n32 and you'll start to believe that designers must still favor npn over pnp when it comes to interfacing..... For a bit more reinforcement, take a look at what TI and others refer to as relay drivers, and you may soon start to wonder where one would find and use pnp.

The fact is that if electronic designers had their way, then sourced output cards and sinking input cards would likely never have been invented. Sinking outputs came first, and are still a bit more versatile. The trouble was that they went against the normal logic that electrical personell were accustomed to; that of feeding current to a load...... Sinking outputs confused them, and thus now we have both......Any less confusining now??
 
Hi Everyone,

I am more familiar with 4-20ma circuits when it comes to sink or source. It's always seemed so simple to me. If the device supplies the power it sources. Otherwise it sinks. For example, I just completed a installing Gas Turbine control panel upgrade. The Turbine Control Panel (TCP) drove a VFD with a 4-20ma output signal. The TCP had the option to power or not power the output. The VFD had the option to set sink or source. The engineer set the output to power and the VFD to source. That didn't work. I got into a discussion with several very experienced engineers and technicians about which way to set the VFD. The consensus was no consensus. It seemed obvious to me, so I just set the VFD to sink since the TCP was providing the power.

Typically on TCP's we only use dry contacts for switch inputs and typically we power all outputs, so I am not real familiar with the NPN and PNP devices. It seems to me though that if the negative side of the device is connected to the PLC input the PLC is sinking. If the positive side of the device is connected then the PLC is sourcing.

Is this an over simplification?

This forum is great for opening me up to how thing's operate in different industries. The expertise here is always appreciated.

Andy
 
I am very happy to see you Prof.Bill

Dear All
My post is not for answer (I am sorry).
Just want to greating with my internet teacher Prof.Bill Simpson.
He was very kind to me.
His software (logix pro) is very useful for the one who want to study plc.
www.thelearningpit.com

I am very happy to see you here. :p :p
All the best to you Professor.

Respectively,

platootod

sawassdee krub.jpg
 

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