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"NPN/PNP SOURCING/SINKING"

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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Mar-28-02, 10:11 PM (EST)
"NPN/PNP SOURCING/SINKING"
So... a couple of weeks ago the NPN/PNP SINKING/SOURCING question came up again.

I decided to ask the electricians that work with me what they knew. I was disappointed with what I heard. So I drew up a bunch of sketches for them. I thought I'd share them with those that need to know.

Be aware, this is only a portion of all of the factors that apply to this subject.
fig-1

fig-2

fig-3

fig-4

fig-5

fig-6

fig-7

fig-8

fig-9

fig-10

fig-11

fig-12

fig-13

fig-14

fig-15

So, after going through this with them, they seemed to get the hang of it.

Hope this can help someone.

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 Table of contents

RE: NPN/PNP SOURCING/SINKING, Quick, Mar-29-02, (1)
RE: NPN/PNP SOURCING/SINKING, Terry_Woods, Mar-29-02, (2)
RE: NPN/PNP SOURCING/SINKING, Tom Jenkins, Mar-29-02, (3)
RE: NPN/PNP SOURCING/SINKING, Pierre, Mar-29-02, (4)
RE: NPN/PNP SOURCING/SINKING, Al Boake P.E., Mar-29-02, (5)
RE: NPN/PNP SOURCING/SINKING, gbradley, Mar-29-02, (6)
RE: NPN/PNP SOURCING/SINKING, akreel, Mar-29-02, (7)
RE: NPN/PNP SOURCING/SINKING, Pierre, Apr-03-02, (11)
RE: NPN/PNP SOURCING/SINKING, Terry_Woods, Mar-29-02, (8)
RE: NPN/PNP SOURCING/SINKING, Vince, Mar-29-02, (9)
RE: NPN/PNP SOURCING/SINKING, Terry_Woods, Apr-03-02, (10)
RE: NPN/PNP SOURCING/SINKING, Bernie Carlton, Apr-03-02, (12)
RE: NPN/PNP SOURCING/SINKING, Vince, Apr-03-02, (13)
RE: NPN/PNP SOURCING/SINKING, Bernie Carlton, Apr-04-02, (14)
RE: NPN/PNP SOURCING/SINKING, Jose, Apr-05-02, (17)
RE: NPN/PNP SOURCING/SINKING, Jose, Apr-05-02, (15)
RE: NPN/PNP SOURCING/SINKING, Jose, Apr-05-02, (16)
RE: NPN/PNP SOURCING/SINKING, rsdoran, Apr-05-02, (18)
RE: NPN/PNP SOURCING/SINKING, Terry_Woods, Apr-05-02, (19)
RE: NPN/PNP SOURCING/SINKING, John Waalkes, Apr-17-02, (20)
RE: NPN/PNP SOURCING/SINKING, Terry_Woods, Apr-17-02, (21)
RE: NPN/PNP SOURCING/SINKING, Mike, May-18-04, (22)
RE: NPN/PNP SOURCING/SINKING, Vineeta Mangalmurti, Apr-07-06, (23)

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Messages in this topic

Quick - (3 posts) Click to check IP address of the poster Mar-29-02, 07:27 AM (EST)
1. "RE: NPN/PNP SOURCING/SINKING"
Hey Terry,

I hope that your company doesnt supply wood to home depot!

I was there recently and out of a whole bunk of 2x, could not find a straight one in the bunch.

Sorry, i know off subject but i still had to ask.

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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Mar-29-02, 07:50 AM (EST)
2. "RE: NPN/PNP SOURCING/SINKING"
LAST EDITED ON Mar-29-02 AT 07:53 AM (EST)

I've seen very little of our lumber at Depot. Our main bread and butter with depot is hardboard.

I agree that it is hard to find a straight 2x at some of those places. Parr is one of our bigger lumber buyers and they seem to get very good 2x's.

And, yeah, you're right; that is pretty far of from NPN/PNP.


So... OK, I'm curious... Who are you?

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Tom Jenkins - (975 posts) Click to check IP address of the poster Mar-29-02, 09:17 AM (EST)
3. "RE: NPN/PNP SOURCING/SINKING"
Very impressive, Terry. Maybe Phil would add this to the tutorial - we get a lot of questions on this topic, and I've never seen a text that explained it as clearly!
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Pierre Click to view user profile - (470 posts) Click to check IP address of the poster Mar-29-02, 10:01 AM (EST)
4. "RE: NPN/PNP SOURCING/SINKING"
Got to admit, this is a darn pretty nice piece of work !

If it looks like a Cat...

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Al Boake P.E. - (6 posts) Click to check IP address of the poster Mar-29-02, 11:34 AM (EST)
5. "RE: NPN/PNP SOURCING/SINKING"
Thoroughly impressed. What a good explanation. My hat is off!
Al
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gbradley Click to view user profile - (205 posts) Click to check IP address of the poster Mar-29-02, 11:35 AM (EST)
6. "RE: NPN/PNP SOURCING/SINKING"
Congratulations on your 1000th post!
I'll give you my 96.7% approval rating, and you know what that's worth.
I remember not too many years ago trying to figure out sinking and sourcing. I had to use your waterfall analogy to make it clear in my mind (though I used a kitchen sink, and fauscet). I wish that I had this post then.
Keep up the good work!


BTW Quick, if you buy lumber at 7:30 P.M. the pallet has already been picked through all day long. This leaves nothing left but the warped 2X4's. If you ask an associate to bring down a new pallet, you'll find that most on the pallet are straight.


George Bradley

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akreel Click to view user profile - (74 posts) Click to check IP address of the poster Mar-29-02, 01:29 PM (EST)
7. "RE: NPN/PNP SOURCING/SINKING"
"Not Poniting iN"...

GENIUS!!!!!!
Why didn't anyone show me that one sooner?

AK

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Pierre Click to view user profile - (470 posts) Click to check IP address of the poster Apr-03-02, 09:01 AM (EST)
11. "RE: NPN/PNP SOURCING/SINKING"
In french schools we used the term "Penetrating" and "Non-Penetrating"

I wonder why use these term.
Guess french had something to do whit it

If it looks like a Cat...

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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Mar-29-02, 07:06 PM (EST)
8. "RE: NPN/PNP SOURCING/SINKING"
LAST EDITED ON Mar-29-02 AT 07:12 PM (EST)

Thanks to all. It's a thing that's been bugging me for a while. I just had to get it out of my system.

I have the slides available in GIF format for anyone that cares.

BTW
I am still working on Kalle's "2-Guys/2-Girls and a single pair of what-cha-ma-call-its". (For those that don't know, it's a Karnaugh Map solution to a sequential exercise.) Coming Soon!

P.S.
Thanks, George. I hope to crack another grand or two before... well, soon.

P.P.S.
QUICK... I think I know who you are... Didn't I used to see you and John burning up electrons on the computer in the "Room-I-Built-for-John"?

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Vince - (52 posts) Click to check IP address of the poster Mar-29-02, 08:52 PM (EST)
9. "RE: NPN/PNP SOURCING/SINKING"
If it takes that long to explain PNP vs NPN imagine how many hard drives you could fill explaining rocket science.
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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Apr-03-02, 08:15 AM (EST)
10. "RE: NPN/PNP SOURCING/SINKING"
Vince,

Your comment has been nagging in the back of my mind (what little there is left of it).

It occurs to me that the amount of hard-drive space needed would be something near the amount needed to record Human History.

I don't think it would be enough to simply record the formulas... you would also need to record the history behind the formulas... That is, When and Why were these formulas created or at least, How were the relationships that led to these formulas evaluated, studied and finally manipulated into something meaningful for us.

You need to have all of that info recorded because ALL INFORMATION that we have ever developed is subject to re-examination!

With hard-drives getting to the size of T-Gigs (is that the right acronym?), maybe we would only need one or two hard drives.


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Bernie Carlton Click to Email Bernie Carlton - (73 posts) Click to check IP address of the poster Apr-03-02, 10:56 AM (EST)
12. "RE: NPN/PNP SOURCING/SINKING"
Just for info - the sizes above Gigabyte (each 1024 times the previous)

Terabyte, Petabyte, Exabyte, Zettabyte, Yottabyte

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Vince - (52 posts) Click to check IP address of the poster Apr-03-02, 07:45 PM (EST)
13. "RE: NPN/PNP SOURCING/SINKING"
I was almost overcome with guilt for my negative comment.
But it opend up a window of information I would not of had otherwise... mmmmmm.. Zetabyte? mmmm...Yottabite?? these terms are new to me!
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Bernie Carlton Click to Email Bernie Carlton - (73 posts) Click to check IP address of the poster Apr-04-02, 01:17 PM (EST)
14. "RE: NPN/PNP SOURCING/SINKING"
I got the information from a nifty 'units conversion' program available at http://www.joshmadison.com/software
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Jose - (4 posts) Click to check IP address of the poster Apr-05-02, 00:14 AM (EST)
17. "RE: NPN/PNP SOURCING/SINKING"
does this work
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Jose - (4 posts) Click to check IP address of the poster Apr-05-02, 00:04 AM (EST)
15. "RE: NPN/PNP SOURCING/SINKING"
I really think your pictures make a very good illustration, but let me try this in my own words so you can correct me if I am wrong. Basically, with all those diagrams all you are saying is with sourcing and sinking, is that wether its sinking or sourcing depends on which way the polarity of your voltage is wired to your plc and field device and which configuration they are in, a npn or pnp. So when you get a change in potential to the base of your field device or plc it is going to conduct, in the amount of voltage proportinate to what is on the base,and the way the current flows, either from your field device to your plc, or the other way around is how you determine wheter they are sinking or sourcing.
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Jose - (4 posts) Click to check IP address of the poster Apr-05-02, 00:05 AM (EST)
16. "RE: NPN/PNP SOURCING/SINKING"
I really think your pictures make a very good illustration, but let me try this in my own words so you can correct me if I am wrong. Basically, with all those diagrams all you are saying is with sourcing and sinking, is that wether its sinking or sourcing depends on which way the polarity of your voltage is wired to your plc and field device and which configuration they are in, a npn or pnp. So when you get a change in potential to the base of your field device or plc it is going to conduct, in the amount of voltage proportinate to what is on the base,and the way the current flows, either from your field device to your plc, or the other way around is how you determine wheter they are sinking or sourcing.
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rsdoran Click to Email rsdoran - (583 posts) Click to check IP address of the poster Apr-05-02, 00:50 AM (EST)
18. "RE: NPN/PNP SOURCING/SINKING"
Jose the point of that was to show polarity ..ie current flow and the relationship to devices used with plc's.

The elusive or hard to understand thing about current flow is that it is from negative to positive...conventional flow is opposite of that.

Therefore PNP ie Pointing N means that the + (positive DC voltage is connected to the input common) and the - is connected to the device used for the input.

NPN ie NOT Pointing N is the opposite...negative - is connected to input common and + (positive) is connected to device.

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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Apr-05-02, 08:21 AM (EST)
19. "RE: NPN/PNP SOURCING/SINKING"
Jose,

Thanks for the compliment.

Now, with respect to the terms SOURCING and SINKING
The relationship is as simple as Figures 1, 2 and 3 indicate.
At the bottom of Figure 2 is written...
SOURCING means FROM the POSITIVE (meaning, DIRECTLY from the POSITIVE).
SINKING means TO the NEGATIVE (meaning, DIRECTLY to the NEGATIVE).

In PLC Input/Output signaling, the transistors are not operating under the proportional characteristics which you will find in transistor amplifiers. Instead, these transistors operate in SATURATION - as in COMPLETELY ON or COMPLETELY OFF (except for leakage).

When one of the transistors turns ON, it essentially creates a SHORT between the Power Source and the "other thing".

If the "other thing" is a coil in the field, then the transistor is a PLC Output. One side of the coil in the field is already connected to one side of the power source (either side). While the PLC Output is OFF, the other side of the coil is essentially isolated.

So, when the Output transistor turns ON (goes into Saturation) the Emitter/Collector connection becomes a SHORT and the transistor connects the isolated side of the coil to the other side of the power source, thus completing a circuit and driving the coil.

In general, the Polarity doesn't matter as long as you are consistant and meet the requirements of the hardware you are using. That is, some Outputs are designed to work ONLY as a SOURCING type, while others will ONLY work as a SINKING type.

The point of the illustrations is to show that terms SINKING and SOURCING are nothing more than relative indications of the direction of CONVENTIONAL Current Flow with respect to a particular device and a Power Source.

Going back over the Illustrations I see that I neglected to include an important point with respect to the field devices.

There should be a Figure-9A showing a PNP field device SOURCING to the PLC.
Likewise, there should be a Figure-10A showing an NPN field device SINKING the signal from the PLC.

I did make the point in Figures 11, 12, 13 and 14 with respect to the PLC Output. That point being...
SOURCING FROM a PLC can be accomplished by an NPN or a PNP in the PLC Output.
SINKING TO a PLC Output can be accomplished by an NPN or a PNP in the PLC Output.

Each of those configurations is commonly available from the various PLC manufacturers (Certainly, Siemens, G-E and AB).

The same can be said about field input devices.

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John Waalkes - (155 posts) Click to check IP address of the poster Apr-17-02, 00:34 AM (EST)
20. "RE: NPN/PNP SOURCING/SINKING"
Good Lord! You have waaaayyy too much time on your hands

Nice job, tho...


John

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Terry_Woods Click to view user profile - (1058 posts) Click to check IP address of the poster Apr-17-02, 06:44 AM (EST)
21. "RE: NPN/PNP SOURCING/SINKING"
No, John,

I know you're just kidding, but, I don't have "...waaaayyy too much time on your hands...".

I don't have nearly enough time on my hands.

I do stuff like this all the time. As well as doing the PLC and Electrical Design stuff, I'm a Technical Writer, Illustrator and Trainer. I'm working towards the future with my design work and cleaning up my behind with documentation. And just like a guy with diarrhea, that paper work is never done!

These illustrations were made, first, for me, and then, for my guys at work. I would have made them whether there was a PLCS.NET or not. I just shared what I had.

I appreciate the compliment. If you have any criticisms or suggestions on how to make them better, I would appreciate those as well.

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Mike - (13 posts) Click to check IP address of the poster May-18-04, 10:07 PM (EST)
22. "RE: NPN/PNP SOURCING/SINKING"
Terry, just thought I'd say...awesome. I'm up for a raise at work (as an Industrial Maintenance Tech. at a 100% Omron and a Japanese owned company) and our new policy is a pay for skill type raise system. I knew ahead of time that PNP and NPN stuff would be on the test. Since it's been seeeeeveral years since I attended trade school, your info was a world of help. Even though for years I've practiced...if it don't work one way, try it the other... that's not gonna cut it for the test. Anyway,...thank alot for the good info.
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Vineeta Mangalmurti Click to Email Vineeta Mangalmurti - (1 posts) Click to check IP address of the poster Apr-07-06, 04:24 AM (EST)
23. "RE: NPN/PNP SOURCING/SINKING"
I really appreciate your efforts in making these diagrams for simplifying the sourcing and the sinking concepts. I am sure I am storing these for my future reference and explanations. ;)
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