Sinking and Sourcing PLC Inputs with PNP NPN Sensors
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- เผยแพร่เมื่อ 6 มิ.ย. 2024
- We’re going to talk about sinking and sourcing PLC inputs, PNP and NPN outputs, how to determine which type of sensor you need depending on your PLC input, and how to wire your PLC input or PLC output.
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th-cam.com/users/TimWilborne
How I remember- Count the Ns. PNP has one N so sourciNg. NPN has 2 Ns so siNkiNg.
That is a good one, thank you for sharing Dan!
This is helpful. TY.
Found this useful to remember 😃
Great technique
Good way to remember
Thank you for in-depth explanation and it confirms what I thought it was. I’m a new industrial electrician trainee.
You are welcome.
Your videos are a great help. I’ve been building control systems for about 40 years, and I’m still learning. It would be a big help to some if you did a video on encoders / open collector inputs, etc. I do about 2 systems a year with encoders, and they can be pretty confusing to anyone just starting out. I really appreciate the work that you do on these videos.
See if any of these encoder lessons help. Thanks for watching!
twcontrols.com/lessons/tag/Encoders
Watch till the end of the video, it's worth it! Thanks Tim
Thanks for watching Alan!
Now Finally I clearly understand Sinking and Sourcing.
Always Love Your Videos. I have Learned a lot from You Videos and looking forward to do the same in Future.
Keep up the Good Work Tim👍
Thank you Chirag!
Best video explaining sinking and sourcing inputs or outputs. Clear and precise
I appreciate that!
You included the AB manual as a ref! Nice!! :) Ok, so to do PLC's.... well, I have to pay attention to PNP and NPN but the simple side of me says, "It's a switch, it does not care, it is going to complete the circuit!" Yet an Output has power going OUT from it to something like a relay! .......and the Inputs have power going into it because it needs to see the 24vdc coming in as confirmation that the input is indeed there.
Hey Tim, I got a Controls /Automation Test Eng. Job at a Nutracueticals (Vitamin) packaging
Corporation in Phoenix. Interviewed with the Controls Engineer 08/23/2021. Left with him hiring me. Thank You for all the Excellent Educational videos. Now I went to George Brown University for PLC II, but its been awhile. David P.
That is great news David. Congratulations on your new job!
A very well informative presentation. Yours is the first channel i ever subscribed. Hoping to see more off from you.
Thanks! Normally we post a video every week.
Well Tim continue with the great work you been doing. The confusion will be gone with the practice.
Practice is the key :)
Thank you for the time that you take to explain PNP and NPN sensors and how they work. I've learned a lot by watching this video. Once again, thank you very much.
Glad it was helpful! Here is a follow up video on PNP and NPN sensor selection.
th-cam.com/video/AoeIpAVufHo/w-d-xo.html
Love it , i watched so many video about sinking and sourcing they are fantastic but within 1 week i forget everything lol. Now with your simple picture everything gone stay for lonnngggg time in my head. Regards
Glad it was helpful!
you're such a good dude Tim. you refused to put the manufacturer on blast that had misleading sinking and sourcing information. You don't care to hear about credentials. You care about the next generation of automation professionals. I hope to reach your level of skill and professionalism one day, and i can't wait to take your class.
Thanks Justin. Feel free to reach out when you are ready and we'll work out the details.
Thank you Mrs . Willbourne it was one of the best explanation that I ever had
You're very welcome!
Thank you so much! Currently struggling through a PLC class for engineering school...your video helped me a lot with understanding the wiring, concepts, and terminology. Cant wait to check out you other content! thanks again!
Glad I could help you out Michael!
@@TimWilborne 1.can we use capacitive touch pad switch (with 5v /24 v dc relay )......in place of start/stop/selector switch ? in a 24 v dc PLC?
2. As we are using retentive timers......how we can design ladder logic for PLC.. so that process start ITSELF after power supply resumes ? (i.e ..not starting with the help of start switch)
Thanks this bye far best video on utube on clarifying npn and pnp. Great job
Glad it was helpful! Here is a follow up clarifying one difference.
th-cam.com/video/AoeIpAVufHo/w-d-xo.html
Sinking or sourcing, or high side switch or a low side switch 😂. Active high or active low, pull up or pull down 😁 Sometimes it makes a hell of a confusion. It's nice that someone took the time to clear things up in understandable way!
For one of my application (egg counting system) previously I used PNP, and the result was that I was getting short on the counts by 10k. I then used NPN, with 24V going to the PLC com and receiving a negative input on the PLC card, and the cout was aproximately perfect.
Interesting application example Nikhil. I might try to replicate it for a video.
Very clear demonstration and effective easy to understand more power to you Sir
Thank you Roberto!
I was not understanding the reason why the PowerFlex inverter's wiring diagram shows an inverted logic regarding the polarity of the sink or source Digital Input. But after watching this video I realized that in this case, the reference is the wiring and not the internal connections of the digital inputs. Thank you for the explanation.
You are welcome!
Just had my 3rd interview/ walk through at a juice bottling plant for an electrician position. Hoping I made a good impression with the controls engineer and others and land the job. You can only learn so much in vocational training and on the job. I feel like I'm learning everyday in this field. Thank you for helping me review basic skills, that are imperative to plant maintenance work. Very helpful.
Glad to hear that Matt, it is hard to beat on the job training!
Hey Tim, thank you for video. Now I have clear picture of sinking & sourcing. Love from india.
Glad I could help clear things up!
I used the same plc using a Balluff as a level sensor ( never used it before). Nobody knew how to wire it into the plc. finally got it.
Glad I could help Dwayne.
Thank you so much for your clear explanation Sir!
Most welcome!
I 🎓 graduated as Tim youtube engineer follower this guy master any one. Also his products are fantastic.
Thanks Luis!
I swore if i watch this enough it would CLICK thats not a PLC PUN, by George I think IVe GOT it !...finally got it THANKS TIM
Glad to hear Chris!
Thank you for this wonderful video.
You are welcome Andy!
Great Video Tim!!!
Thanks Al!
Thank you Tim , you are the best .
You are very welcome.
I have been and Automation tech for about 8 years now. And do you know how much "vibrant" debate this topic brings haha. Specially with the new techs haha. Great Video.
Yes, the struggle is a right of passage 😂
I’m sure someone has already answered your question to why NPNs are faster than PNP. It has to do with transistor make up. The mobility of electrons is faster than the mobility of holes. Cute video!
Yes, I should do a follow-up on the difference. Thanks for watching!
great content and very informative.
Glad it was helpful!
PNP & NPN thanks never understood it to much thanks for the info now i have a little better under standing
Glad to hear it. Let me know if any particular questions come up for you.
Thanks for all the knowledge
You are welcome Ernesto!
awesome explanation
Thank you!
like ur videos for the simple way of explaining , thank u soo much...
very very clarifying
You are welcome, glad you found them helpful!
Watched Twice , Big Like , super subscribe
Thanks Man !
Thanks for the sub!
Great video, really helpful
Glad it was helpful!
Im buying merch this channel is very helpful thanks Tim
Thanks!
Great video, thanks for the info.
Glad it was helpful!
Excellent video! Sometimes those terms can be confusing, Good job breaking it down!
Thanks Jason. It was a learning experience when I got looking at different manufacturers definition of sinking and sourcing.
The real problem with all this is the confusion between conventional vs electron current flow. Could have fixed this in the 40's when electronics really took off. But the scientists and engineers like to confuse technicians as much as possible. Thanks a lot Benjamin Franklin!
Not really, here is a video :)
th-cam.com/video/QV6zFhc4c00/w-d-xo.html
Very helpful. Thank you so much..
You're very welcome!
I'm a Electrical Engineer and learnt a lot from this guy. Thank You Guy.
You are welcome!
Finally my concept is clear thanks..!
Glad to hear
Nice explanation
Thank you
good video was very helpful, thanks
Glad to hear it Angel!
Thank You!!! Very helpful!
You're welcome!
Thanks! Great Video
Glad you liked it!
Thanks Tim
You are welcome
Another good video would be reading the diagrams on sensors and how to wire them to your plc. Some are very confusing especially when you have a retro fit or replacement in the field that doesn't match the original.
That's an excellent idea Jacob! I'll put it on the list!
Excellent
The way I go about sensors is PNP is ( positive ) NPN ( Negative ) and it is the actual thing that is going inside the sensors, it's the composition of the semiconductor material inside the sensors, PNP is N material sandwiched inside 2 P material and to bias it correctly, you need to connect it to same polarity ( + ) so they repel each other and start to conduct.
HUGE THANKS !!!
You are welcome.
@@TimWilborne do you offer a certification on you your PLC course…?
@@One-way It comes with a certificate of completion
good work
Thank you!
To answer the question why do we have NPN & NPN? It was my understanding from an "older instructor" who has been in high speed programming and impressive resume told me that either PNP or NPN (not sure which one, I think it was NPN) predates the other. So the reason why you have both PNP and NPN is because in the past they could only make the electronics one way. Then they figured out how to make the PNP, I believe. That the best I recall from a few years ago. I recall him saying what Tim said in the video, that the concern was that if a wire is pinched or something cause something to ground the could cause somethiing to run which you did not want. In the case of PNP, you was more likely to blow a fuse.
Good explanation Mike. NPN is older and for some reason slightly faster. I'm going to do a video on it as soon as I have time to study on it. Thanks for watching!
Tim! 😅🤣😂 Captain Obvious! Your face was perfect when you slide the other paper up showing Sensor and PLC input!
Some people 😂
Хороший уровень подачи материала
Thank you
Why would I remember this when I can just lookup this vid whenever I need it? 😁
You may not have cell service some day 😀 Thanks for watching!
What a video 👏🏻
Thanks!
thank you!!
You're welcome Phillip!
you are worth more!
Thanks!
Study up on transistors of you’d like to know more about NPN and PNP wiring protocols.
good day Tim
it is nice video thsnks very much.
my question is why and when to use stinking or sourcing sensors?
That is a tough one to answer because there are so many variables but the big factor that will determine it is what your inputs are compatible with.
Good informative ....
Glad you liked it!
I liked the dig on posting credentials on comments, lol!
😁
Nice video too much love from india.
Thanks a ton
great video I'm use to the PNP/NPN terminology. when it comes to sinking/sourcing I always have to stop and think for a second. I also like power/not power I never heard that one before that's a easy way to think about it. something that might help some people or it may just be me. but when I think of PNP setup meaning both my inputs and outputs are PNP. I think of it as Positive in/Negative common Positive out. Or Positive In to input/ Negative common on input card/ Positive to common on output card. Or NPN Negative to input/Positive to input card common/Negative to output card common. again I don't want to confuse people but that's just how I think of it.
Good to know!
Great video
❣️🇮🇳❣️
Thanks 🤗
I have that the ECMs in vehicles take advantage of sourcing inputs and decrease wiring costs by tying the input switches to chasis negative thereby needing only one conductor to the switch.
Yes, a clear advantage when you use the chassis for one of the conductors.
Sourcing: Providing, like a water faucet. Sinking: Draining, like a sink drain.
thanks a lot
You are welcome!
I am a new subscriber
Thanks!
A simple way to understand this is, If give 0v to DCOM then it's sinking and if you give +24v to DCOM its sourcing. And for sensors, NPN requires sinking and PNP sourcing.
But as I discovered in the video, not all manufacturers follow those general rules of sinking and sourcing. Some of them swap the terms.
@@TimWilborne Hey Tim, it's nice to see you reply so quickly. Of course, you've way more experience than me regarding plc's. So, I was thinking what other manufacturers swap these terms?
I've mainly worked on AB,ABB, Siemens and Schneider modicon and I found they all use the general method of sourcing and sinking. Pardon me if im wrong.
As I tell in the video, I'm not going to go pointing fingers but yes some of them swap the terms especially on the outputs.
It's much easier to find that burnt wire and replace the IO fuse than it is to figure out why intermittently the machine does something on it's own. Especially given that wires+vibration+metal = short to ground.
Thanks
You are welcome.
Grazie, molto interessante!
Prego
Im looking for this because i am troubleshooting an auto hallowblocks/concrete paver machine.. its not operating automatically and i found out some inductive proximity sensors are defective.. i also wanna know what type of sensor is needed in this kind of automation, is it npn/pnp, n.c or n.o.
I want to know what you know… starting out in the PLC world and excited about it
Hi DJ, here is a good place to start.
twcontrols.com/plc-lessons
Good my teacher
Thank you! 😃
When you were mentioning Applications to use sinking vs sourcing...
I think one thing that should be added is that if you are dealing with system that uses a variety of sensors that requires different voltages (e.g 5vdc, 10vdc, 12vdc, 24vdc etc) you can use a plc with sinking outputs and connect for example a 5v sensor on output 1, a 10v sensor on output 2, a 12v sensor on output 3, etc. this works because you’re switching the negative side of the sensor. All commons/ negative side of each power supplies are almost always tied together somewhere whether it be through internal chassis ground, on a PCB negative rail, or directly tied together through terminal blocks.
Switch is done using NPN.
Its not posable to use differed voltages on a sourcing PLC because your switching the positive side of the load. If you were to connect the positive side of power supplies of different voltages your output voltage would end up being whatever the highest voltage power supply is. (e.g 5v, 12v, 24v = 24v out) So you would end up a single output voltage instead of different voltages. Because switching is done using PNP.
So all that being said documents for both PLC and Sensors vary from manufacturer to manufacturer and series. I think the only way to know what you have or need is to look up the internal schematics for each PLC and sensor and check the type of transistor being used in the PLC and then the type of transistor being used in sensor and not rely solely on the manufactures product description. Yes this is/ would be a daunting task but its really the only way I can see to be 100% certain you end up with a proper system design.
That is an interesting thought about using sinking inputs for multiple voltages. The PLC inputs even when sinking usually are for specific voltage so I'm trying to figure out whether that's a good practice or not.
Do you have any PLC manuals you can think of that show examples of this being done?
Tim Wilborne I cant say that Ive seen it in a plc manuals. But thats how 90% of electronic circuits work in general.
Just for an example. Take a computer for example this is probable not the best analogy but.... Inside you have common rail aka ground, 3.3v+ rail, 5v+ rail 9v+ rail, sometimes 12v+ rail and 19v+ rails. All these voltages are used to power different components of the system but all use a common negative rail.
Ok so your thinking well maybe they’re all being powered from the same power source so thats why they can get away with that. No not always.
For example servers with redundant power supplies for example. They still use common negatives and electrical grounds.
Another example for instance is a powered USB hub. Most of the time the hub will be powered using a separate 12v power supply. But that power supply’s negative is going to be tied to electrical and chassis ground of the hun, along with the shield of each of the usb connectors. On the computer side the usb is tied to electrical ground and negative rail.
Another example is communication ports RS232, rs485, etc all use common grounds between devices and operate using different voltages and powered by different power sources.
Basically what I getting at is ground and Negative are typicly handled the same and required in most applications to prevent ground loops in a system.
By the way Im NOT claiming to be an electrical engineer by no means. And if anyone cares to prove me wrong or would like to correct me. Please do it somewhat respectfully, so I can better my knowledge.
So... Allen Bradley’s manuals don’t appear to list full specs for their products they just list basic value of 24v for inputs and outputs. I dont see anywhere in their manuals where they list dropout voltages for any of their I/O’s. To be able to use different voltages you would need to know the dropout voltage of the inputs.
Don’t dog me for this.. but all of automation directs plc’s list the dropout voltages and the stable min max voltages for all their plc’s and modules I/O’s.
For instance click’s I/O’s operate between 5~24v. and I know mixed voltages work on click’s and brx’s
Since Allen Bradley doesn’t seem to have theirs listed if you have a variable bench power supply? You could hook it up to one input and set it at the 24 V you know works. Then slowly lower the voltage until the input turns off. Then slowly raise the voltage. Until it turns back on.
It’s either going to turn on or off at a higher voltage. It will not be the same voltage for both. Take that number and add a min of 2~3v and that should give you your min stable voltage.
If it turns off at 20~24v then I guess they must have fixed voltage inputs. And would guess if you ohm out the input its high resistance.
@@mumbles1justin I can see how this would be a good practice for a PLC output, page 2-35 of the Click manual clearly shows an example of it.
But while I think this would work for a PLC input in most cases,I don't think this would be a good practice. Even on our devices, the circuitry is different for 5VDC sinking inputs compared to 24VDC sinking inputs to adjust the switching threshold.
Looking on that same page 2-35 of the Click manual, the ON threshold is 19V and the off is 4V (7V for X3-8). 12V or 5V may switch them but are not in the range. That seems to be the case for all of the Click inputs except the C0-08ND3 which is designed for 12-24V whose ON threshold is 8V and OFF threshold is 3V. And personally I wouldn't like having to draw a 24V input down to 3V to get it to turn off. As a machine shows some age it could cause problems.
I have a variable power supply, maybe I'll play with some various devices to see how they perform under different voltages. Great conversation as always Justin. Thanks.
I went back and looked at some of my old job notes and it looks like I used sinking outputs to interface with a machine that had 5v, 12v, and 24v logic.
On the PLC inputs it utilized 12v and 24v triggers. To get 5v inputs I used an opto coupler at the rack to “convert” the 5v to 24v to trigger the plc input.
So Ill have to agree with you that most plc’s having fixed voltage inputs.
All current flow is determined by the convention used.. conventional flow (ve+ to ve- )… or electron flow the opposite of conventional flow..
Hi Tim, great video! Love your learning video series! Just got a stupid question, does PLC have internal physical Relays or coils for digital output? Searched over internet, someone says yes, someone says no. I am confused. Could you clarify this question for me? Many Thanks!
Oh my this is a popular question this week! NO NO NO! A PLC has memory areas, not magical internal relays. They can be different sizes, in the case of your output it is a BOOL data type which can hold a 0 or a 1. Ones that are associated with an output are no different than ones you create as far as PLC programming. They just happen to be used to update the physical outputs.
I guess I'm going to make a video that tries to clear this up soon, but here is an older one of me ranting about people using the terms normally open, normally closed, and relay to describe PLC instructions.
twcontrols.com/lessons/plc-training-plc-instructions-are-not-the-same-as-electrical-symbols-normally-open-and-normally-closed
Great video Tim. Were did you learn all this? Are you self taught?
Thanks Chris
Hi Chris. Most of it was from the College of Hard Knocks, that is why we try to make sure we make this information freely available to others. Thanks for watching!
As a rule of thumb I was taught it is common practice in 24vdc applications to sink inputs and source outputs. I was wondering your take on that philosophy?
I hate to generalize or make rules but I'd say that is a true observation.
Normally, outputs are supplying power to your device = outputs are the SOURCE of power for your device. Inputs are provided power from your device = inputs SINK up to a device for their power. 😆 couldn't think of a good one for sinking
While that is typical for most Allen Bradley configurations, it isn't true for all brands and almost all can have sourcing inputs and sinking outputs. The most notable being high speed applications.
Hey Tim do you do classes I really want to get more knowledge on plcs for my job
Yes I do. See link below.
twcontrols.com/plc-lab
Good luck convincing engineers to leave their "credentials" out of the comments.
I’m a student engineer, and I agree with ☝️ Chris’s comment. I’m going to use the $hit out of my title. I’m working hard for it. LMBO. 🗣
PNP provides power
NPN needs power
Hello Tim,
I was wondering if you ever created a training video on the effects of grounding the positive output terminal on your I/O power to the cards. Could you show the effects on Grounding the Positive Output on the DC Power Supply on your Oscilloscope. Then preform the same illustration on the grounding of the Negative Output side of the Power Supply. Then show how this effects sourcing and sinking PLC'S I/O cards as it relates false Input Signal, Output turn on with out the signal from the Output Card. Also could you explain the effects of lifting the Ground on the Secondary side of the Power Supply. Thank you
Hi Mark. That one is on the list, stay tuned!
@@TimWilborne Thank you. I will keep watching.
this sounds all confusing but in the end i understood that i understood this long ago. its not anymore difficult to understand then when you transport pizza and salad and put the salad on top of the pizza it will heat up the salad but if its under the pizza it wont. when you put a frozen turkey on top of the produce in your fridge it will freeze the produce but if its below it wont. those concepts of dependency logic and positive/negative states really isnt intrinsic to electrical or logical systems. but what do i know i am no EE lol. for every sensor its just important to think what happens if the wires get wedged in a door or other part of machine and make contact internally and what happens if they get ripped of and cant make contact anymore. according to this outcome you have to choose the safer configuration even if it means buying a different sensor.
Love u... Could you provide Siemens plc videos complete series please
I can program Siemens PLCs but at least right now we have much more demand for Allen Bradley videos so that's what we stick to. Thanks for watching!
@@TimWilborne later on . Can you. I need to l Arn Siemens which is frequently used in my places but learning institute are not there so
Nice
Thanks!
I had to run sensor wires into the 1769. Never worked with this plc. Called tech support and also no idea how it gets wired. So with some guessing I got it to work.
It can be challenging!
Dear sir, can you have a video about sinking and sourcing on Siemens PLC S7-300? And how do we select right sensor?
I'll see if I can do one on sensor selection, thanks for watching!
Nice video, do you know NPN or PNP which one popular in USA?
It depends on the application Vincent.
At 15:00 you ask why they use the terms PNP and NPN instead of source and sink. The PNP and NPN terms are from transistor construction and what type of material you have sandwiched in there to create the transistor. And in a BJT the emitter leg will source in a PNP device and on an NPN the emitter leg is a sink. That's why on a PNP transistor schematic symbol the arrow points outward and on a NPN transistor symbol the arrow points inward. Thanks for your videos, looking to change focus and get a new job soon.
Great explanation. Thank you watching and good luck with your job search!
Reverse! NPN points to emitter.
@@rhythmandacoustics Correct........My instructor taught me that the little arrow is a penis. So arrow pointing into the center is a PNP (pee in the potty). Arrow pointing out is a NPN (no pee in the potty.....BHAHAHAHA
"Point in please" and "Never point in" is how we learned in the old days.
Could you explain how to connect load to machine vision camera
That is something I would like to learn about myself. Maybe some day.
would it be also called active vs passive channels? where active channels need two terminals to complete a loop vs a passive channel where you only need the return (-) to complete the loop.
No active and passive usually indicate whether a signal is powered by the loop or powered externally and is usually used for analog signals such as 4-20 mA
At 12:11, Output Module wiring, aren't the output devices in sinking? coz the Output Module is sourced to +24
No they are sourcing because they are sending 24V out of the output.