Sinking and Sourcing PLC Inputs with PNP NPN Sensors

[@TimWilborne]

Subscribe to Become a Better Technician kzbin.info

[@danstaifer2028]

How I remember- Count the Ns. PNP has one N so sourciNg. NPN has 2 Ns so siNkiNg.

[@TimWilborne]

That is a good one, thank you for sharing Dan!

[@Karina_Engr]

This is helpful. TY.

[@olandorobertson2510]

Found this useful to remember 😃

[@rockstarboi44]

Great technique

[@amenlion88]

Good way to remember

[@justinpuzak2558]

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.

[@TimWilborne]

Thanks Justin. Feel free to reach out when you are ready and we'll work out the details.

[@Dadjokes2]

You sir, are awesome! My journeymen have explained this to me but I like how clear and to the point you are on all electrical topics. Thank you!

[@TimWilborne]

Glad it helped!

[@yeeher1671]

Thank you for in-depth explanation and it confirms what I thought it was. I’m a new industrial electrician trainee.

[@TimWilborne]

You are welcome.

[@larslarsen7818]

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.

[@TimWilborne]

See if any of these encoder lessons help. Thanks for watching! twcontrols.com/lessons/tag/Encoders

[@jacksonsimon8632]

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.

[@TimWilborne]

Glad it was helpful! Here is a follow up video on PNP and NPN sensor selection. kzbin.info/www/bejne/d6DIeqN3i9qZftE

[@marwanabou-samra9908]

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

[@TimWilborne]

Glad it was helpful!

[@davidpalmer963]

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.

[@TimWilborne]

That is great news David. Congratulations on your new job!

[@michaelhopkins5823]

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!

[@TimWilborne]

Glad I could help you out Michael!

[@anancrypto2213]

@@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)

[@automationartisan]

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.

[@TimWilborne]

Interesting application example Nikhil. I might try to replicate it for a video.

[@nworaobinna693]

Best video explaining sinking and sourcing inputs or outputs. Clear and precise

[@TimWilborne]

I appreciate that!

[@Iisidjenejiirjrkgawdcv9888yyyt]

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.

[@pedalharder8520]

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!

[@TimWilborne]

Yes, I should do a follow-up on the difference. Thanks for watching!

[@alancordeiro8650]

Watch till the end of the video, it's worth it! Thanks Tim

[@TimWilborne]

Thanks for watching Alan!

[@bettomotta]

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.

[@TimWilborne]

You are welcome!

[@thatdudeoverthere02]

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.

[@TimWilborne]

Yes, the struggle is a right of passage 😂

[@Matt-eb5bj]

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.

[@TimWilborne]

Glad to hear that Matt, it is hard to beat on the job training!

[@rodolforodriguez70]

Thank you Mrs . Willbourne it was one of the best explanation that I ever had

[@TimWilborne]

You're very welcome!

[@elevatesafe9232]

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

[@TimWilborne]

Glad to hear Chris!

[@lutorres2003]

Well Tim continue with the great work you been doing. The confusion will be gone with the practice.

[@TimWilborne]

Practice is the key :)

[@davidstahl8917]

Thanks this bye far best video on utube on clarifying npn and pnp. Great job

[@TimWilborne]

Glad it was helpful! Here is a follow up clarifying one difference. kzbin.info/www/bejne/d6DIeqN3i9qZftE

[@lutorres2003]

I 🎓 graduated as Tim youtube engineer follower this guy master any one. Also his products are fantastic.

[@TimWilborne]

Thanks Luis!

[@rahulas721]

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👍

[@TimWilborne]

Thank you Chirag!

[@shivrankrishen]

I'm a Electrical Engineer and learnt a lot from this guy. Thank You Guy.

[@TimWilborne]

You are welcome!

[@nunyabusiness5075]

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.

[@TimWilborne]

Great explanation. Thank you watching and good luck with your job search!

[@rhythmandacoustics]

Reverse! NPN points to emitter.

[@jimanderson4865]

@@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

[@lastchance8142]

"Point in please" and "Never point in" is how we learned in the old days.

[@dwaynes965]

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.

[@TimWilborne]

Glad I could help Dwayne.

[@lastchance8142]

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!

[@TimWilborne]

Not really, here is a video :) kzbin.info/www/bejne/h4eZq3memJmWZpI

[@mohamed-ld8jh]

good day Tim it is nice video thsnks very much. my question is why and when to use stinking or sourcing sensors?

[@TimWilborne]

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.

[@robertojrcruz8506]

Very clear demonstration and effective easy to understand more power to you Sir

[@TimWilborne]

Thank you Roberto!

[@cheyguvera9680]

Hi sir thank you for your detailed explanation. My doubt is can't we connect plc output sinking ? Only must be plc output should be sourcing only?

[@TimWilborne]

It is very PLC dependent. Some can only be sourcing, some can only be sinking, and some can be both.

[@cheyguvera9680]

@@TimWilborne ok thank you

[@TimWilborne]

You are welcome

[@mikeb2097]

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.

[@TimWilborne]

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!

[@jacobf3510]

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.

[@TimWilborne]

That's an excellent idea Jacob! I'll put it on the list!

[@atifbrema4971]

Excellent

[@JDChaidez]

Yes Sir! Great Job Tim. I Always Wondered How People Knew Stuff I Didn't! Because of Guys Like You, Now I am Smart! S...M...R...T...Dohh!

[@TimWilborne]

I'm glad it was helpful!

[@esherrod9046]

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.

[@TimWilborne]

Yes, a clear advantage when you use the chassis for one of the conductors.

[@Space_Tour1]

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.

[@josedavid8388]

A very well informative presentation. Yours is the first channel i ever subscribed. Hoping to see more off from you.

[@TimWilborne]

Thanks! Normally we post a video every week.

[@vishalmehta6039]

Hey Tim, thank you for video. Now I have clear picture of sinking & sourcing. Love from india.

[@TimWilborne]

Glad I could help clear things up!

[@wesley9427]

PNP & NPN thanks never understood it to much thanks for the info now i have a little better under standing

[@TimWilborne]

Glad to hear it. Let me know if any particular questions come up for you.

[@rajsoparia9886]

At 12:11, Output Module wiring, aren't the output devices in sinking? coz the Output Module is sourced to +24

[@TimWilborne]

No they are sourcing because they are sending 24V out of the output.

[@neerajdwivedi7814]

Sourcing means to loop position to input and sinking means to loop negative to input.. Similarly can you define for PLC output for our Understanding?

[@TimWilborne]

Source and sink are brand dependent, mostly on the outputs but one manufacturer swaps the input terms so always check the manual.

[@neerajdwivedi7814]

@@TimWilborne sir, in interview I was ask.. How we can replace pnp sensor to npn in machine plc, in case we don't have pnp sensor?

[@cmd030]

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.

[@TimWilborne]

Good to know!

[@loutorres0608]

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?

[@TimWilborne]

I hate to generalize or make rules but I'd say that is a true observation.

[@aleemsafdar2120]

Finally my concept is clear thanks..!

[@TimWilborne]

Glad to hear

[@georgealbo]

Could you explain how to connect load to machine vision camera

[@TimWilborne]

That is something I would like to learn about myself. Maybe some day.

[@AungWinHtutGH]

Thank you so much for your clear explanation Sir!

[@TimWilborne]

Most welcome!

[@R1zla212]

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.

[@TimWilborne]

But as I discovered in the video, not all manufacturers follow those general rules of sinking and sourcing. Some of them swap the terms.

[@R1zla212]

@@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.

[@TimWilborne]

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.

[@kevinkesler8154]

I’m wondering if you could post a troubleshooting video for finding bad inputs for sinked devices. For some reason I recently had my butt kicked on a AB 500 system sinked input card with a shorted wire. Thanks

[@TimWilborne]

Here you go! kzbin.info/www/bejne/d6DIeqN3i9qZftE

[@kevinkesler8154]

@@TimWilborne my freaking hero!!!

[@TimWilborne]

😁

[@josesaucedo3199]

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.

[@TimWilborne]

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

[@dwaynes5983]

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.

[@TimWilborne]

It can be challenging!

[@medsihamdi1555]

Thank you Tim , you are the best .

[@TimWilborne]

You are very welcome.

[@Vvkiurv]

Хороший уровень подачи материала

[@TimWilborne]

Thank you

[@adamalbright7285]

Hey Tim do you do classes I really want to get more knowledge on plcs for my job

[@TimWilborne]

Yes I do. See link below. twcontrols.com/plc-lab

[@nabilnajim3269]

hi can explain how make a daily report for f.t view thanks

[@TimWilborne]

Haven't worked with FactoryTalk View in a while.

[@limhuisinn8906]

Dear sir, can you have a video about sinking and sourcing on Siemens PLC S7-300? And how do we select right sensor?

[@TimWilborne]

I'll see if I can do one on sensor selection, thanks for watching!

[@jasonjohnson8373]

Excellent video! Sometimes those terms can be confusing, Good job breaking it down!

[@TimWilborne]

Thanks Jason. It was a learning experience when I got looking at different manufacturers definition of sinking and sourcing.

[@djparsons2627]

I want to know what you know… starting out in the PLC world and excited about it

[@TimWilborne]

Hi DJ, here is a good place to start. twcontrols.com/plc-lessons

[@davidwehage414]

I liked the dig on posting credentials on comments, lol!

[@TimWilborne]

😁

[@codybrasil]

I have searched everywhere and I can find the meaning of the “Q” in the manuals and the “-Q” but with the line on top of it! I thought it would something like NO and NC, but I haven’t found nothing explaining it! Help please! The are always on the cables white and black 2 and 4.

[@TimWilborne]

Don't know, you didn't mention a make or model.

[@codybrasil]

@@TimWilborne that usually comes in every sensor model that we see in the factory, most common on sick sensors

[@mumbles1justin]

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.

[@TimWilborne]

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?

[@mumbles1justin]

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.

[@mumbles1justin]

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.

[@TimWilborne]

@@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.

[@mumbles1justin]

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.

[@khidderali325]

I am learning PLC from scratches what do you advise me? in term of courses and materials

[@TimWilborne]

Here is a great place to start. www.theautomationstore.com/lessons/

[@arbarsabion9217]

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.

[@stevenspencer5948]

Study up on transistors of you’d like to know more about NPN and PNP wiring protocols.

[@akashsharmaaaa]

pnp sensor has 3 terminals : +,- & the sensor o/p terminal which sends 24V w.r.t ground to the input or output port of the plc. While NPN sends 0V.

[@TimWilborne]

Both NPN and PNP sensors can be 2 wire or 3 wire devices. Also you don't "send" 0V. 0V sinks a potential from the PLC input. It is a small detail but it also helps you keep the sinking and sourcing terms straight.

[@akashsharmaaaa]

@@TimWilborne Thanks for clarifying. Also loved your video.

[@TimWilborne]

@@akashsharmaaaa You are welcome, thank you for watching!

[@mornepetersen7003]

Ok here goes, Zero experience sparky - I have a 24v motor that controls a sliding door with 2 proximity sensors, when the door is closed(sensor indicates green and amber light) and I press the open switch the door will open until it reaches the outer end sensor and the motor stops. Now the closed sensor turns to green only. When I press the close button the door doesnt close. I have 24 volts at the switch and the switch is working properly. My question is - is the outer proximity switch supposed to supply power to the junction box to signal for a close command?

[@TimWilborne]

There is 100 different ways you can wire that. You are going to need to trace it out. Good luck!

[@dzheirhald]

can you connect a PNP sensor output to a controller accepting only NPN input?

[@TimWilborne]

The easiest way would be to add a relay to change the logic.

[@markclewis1962]

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

[@TimWilborne]

Hi Mark. That one is on the list, stay tuned!

[@markclewis1962]

@@TimWilborne Thank you. I will keep watching.

[@ernestohernandezmartinez4062]

Thanks for all the knowledge

[@TimWilborne]

You are welcome Ernesto!

[@andyramone8497]

Thank you for this wonderful video.

[@TimWilborne]

You are welcome Andy!

[@dotex2809]

Watched Twice , Big Like , super subscribe Thanks Man !

[@TimWilborne]

Thanks for the sub!

[@FrankRobertson-f6r]

I think this may all depend on whether you learned hole flow or electron flow

[@Junder2982]

great content and very informative.

[@TimWilborne]

Glad it was helpful!

[@alancordeiro8650]

What about OUTPUTs, would you have any tips on those? Sounds simple at first, but some guys say it's more complex

[@TimWilborne]

See if this video helps. It's for the Compactlogix but the principles are the same for most any PLC.

[@alancordeiro8650]

Yeah, this video on INPUT basically does it. My boss told me today that OUTPUT would be the other way around - - simply check wether your PLC OUTPUT is PNP or NPN, then complete the circuit with your load towards the opposite polarity. Loads would have no polarity

[@TimWilborne]

Not sure I understand your question Alan. Both of those videos cover inputs and outputs.

[@alancordeiro8650]

@@TimWilborne Did you by chance send a video link with your previous reply? It won't show on my side

[@TimWilborne]

@@alancordeiro8650 Try this link kzbin.info/www/bejne/p5PVkmuXqtSZecU

[@avinashpandey1935]

Sir,Can I relate the NPN and PNP sensors to NPN,PNP transistors?

[@TimWilborne]

Yes, they are the same.

[@NS-no1li]

All current flow is determined by the convention used.. conventional flow (ve+ to ve- )… or electron flow the opposite of conventional flow..

[@KINTULAWRENCE]

HOW CAN I GET PLC TRAINING KITS ??

[@TimWilborne]

At this link twcontrols.com/plc-trainers

[@ruizjuan3384]

Im buying merch this channel is very helpful thanks Tim

[@TimWilborne]

Thanks!

[@cjwilson1976]

Good luck convincing engineers to leave their "credentials" out of the comments.

[@Karina_Engr]

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. 🗣

[@kracin]

This is a typically hard concept for people to follow, mostly i think because of the nomenclature not used anywhere but electronics. I once again was out at a customer helping get a process running, and somebody had wired an NPN sensor to their sinking inputs. I always think of it in as they look phoenetically, NPN sensor (P is the common between the two. Positive resides on the common of the plc) PNP sensor (N is common between the Ps, so N [0v] is the common on the plc). Sourcing to me can just mean the source of the voltage comes from this point, so activating a PNP Sourcing sensor means the return wire to the plc input will have voltage and must complete the circuit with the Common being the 0vdc wire or "N".

[@kracin]

I'll add too that it's almost comical how many technicians I run into that say "If the lights on, it's working, so it doesn't make sense why the input won't turn on, I think the PLC is bad." A GREAT tool for people to use, veteran and novice, is the Turck TB3-CP80. It will not only power sensors, photo eyes, etc. but also tell you if it's working and whether it's NPN or PNP, normally open or normally closed. If anybody does troubleshooting with sensors, they need it.

[@TimWilborne]

That's a good phonetic. Keeping them straight is half of the battle!

[@nayrbsworld3048]

if the plc is d.i. sourcing the 24vdc will come from that card which come from the 24vdc power of the cpu? or from external power supply?

[@TimWilborne]

You would typically feed +24VDC to the common of the module then take your input to the device but check the wiring diagram of your particular module.

[@nayrbsworld3048]

@@TimWilborne so even it label common it is intended to wire a 24vdc? actually our plc is Allen bradley with sourcing d.i..card.

[@TimWilborne]

@@nayrbsworld3048 I should do a video on this sometime but common, the - of a 24 volt power supply, and ground are three completely different things. Common is simply the common point on the module. On a sourcing module, the common point of the module is the + 24 of the volt.

[@RD-ni7qe]

If I wanted to simply monitor the dry 'alarm' contacts on a bunch of field devices (which are NC, and 'Open' on alarm), should I use sinking or sourcing PLC inputs?

[@TimWilborne]

With a dry contact, you can use either a sinking or sourcing PLC input.

[@RD-ni7qe]

​@@TimWilborne Thanks! Would sinking or sourcing inputs be the most common method for dry contact monitoring?

[@TimWilborne]

@@RD-ni7qe There is no right or wrong answer to the question. Sinking inputs are more common if that helps.

[@ethan073]

Why would I remember this when I can just lookup this vid whenever I need it? 😁

[@TimWilborne]

You may not have cell service some day 😀 Thanks for watching!

[@thebalajitube]

like ur videos for the simple way of explaining , thank u soo much... very very clarifying

[@TimWilborne]

You are welcome, glad you found them helpful!

[@jsbaltimore3405]

I thought an advantage of NPN was sparks in areas where fires are a big concern?

[@TimWilborne]

No spark from a positive of a circuit is the same as a spark from the negative of a circuit. There's no reduction in hazard in these situations. Here's where you would start looking at intrinsically safe amplifiers and barriers.

[@jsbaltimore3405]

@@TimWilborne got it. Thank you. A place where a good friend of mine works said the electrical engineer that heads his department said that was part of why he is so adamant about using NPN sensors. Thank you for clearing that up for me.

[@TimWilborne]

He is probably thinking that it would cause a less intensive spark since the 24+ has to go through the PLC but that would be an assumption and not an engineered reduction in hazardous energy. A spark is still a spark so it is just as hazardous.

[@amalahmed5619]

Thank you but what about transistor output

[@TimWilborne]

These are transistor outputs. They are either sinking or sourcing. Yours may use the terms PNP and NPN.

[@Delta_PLC]

Nice video, do you know NPN or PNP which one popular in USA?

[@TimWilborne]

It depends on the application Vincent.

[@stevenspencer5948]

Sourcing: Providing, like a water faucet. Sinking: Draining, like a sink drain.

[@enzoclass_23]

awesome explanation

[@TimWilborne]

Thank you!

[@pradipprasadyadav330]

Love u... Could you provide Siemens plc videos complete series please

[@TimWilborne]

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!

[@pradipprasadyadav330]

@@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

[@edmarlibuto3421]

Very helpful. Thank you so much..

[@TimWilborne]

You're very welcome!

[@currancarlile8239]

Thank you Tim!

[@TimWilborne]

You are welcome

[@jamesnewman9547]

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.

[@calumcuthill]

Coming from PCB design world, this seems unnecessarily complicated! I’d expect sensors to have push pull outputs (so will sink and source) and the plc to just have a high impedance input (so neither). Although the plc should have optional internal pull down or pull up resistors to deal with sensors that require it. That’s how it works at the microcontroller level anyway. I’d be interested in the reasons why plcs don’t do that. I guess it means some sensors can have just 2 wires rather than 3. But is that all…?

[@JohnnyJr396]

I know you probably explained this, but I have to ask. I’m assuming this is the same with VFDs,. I see drives with sink/source, is this for a secondary circuit to control some load with the drive or are these some inputs that can be programmed to start a drive? I know that’s not a plc question but It’s related. Thanks

[@TimWilborne]

The principle is the same, but the terms can be swapped just as I discussed in this video. For AB, it is exactly the same on their drives as their PLCs.

[@framos9991]

Thank You!!! Very helpful!

[@TimWilborne]

You're welcome!

[@gabrielnimile6617]

Hi Tim,I'm Gabby from PNG and new to plc and automation so please can you assist me on my assignment, about wiring a simple plc rack test bench for testing plc I/O cards. Thank you.

[@TimWilborne]

This video should get you straight on sinking and sourcing. That is usually the biggest hurdle

[@jasonwoods7915]

Before this video I thought I had an understanding of inputs outputs and sensor wiring. Now not so sure. Let me explain. I am an electrician. So I would bring 24v to a limit switch sourcing then from normally open on limit to digital input which is my syncing. Then this would fire the output to let say a solenoid on a valve to get it to open to open back up the limit. I would then bring 0v blue white wire back to 0v terminal block. Not that confusing before. On analog circuits I would use Belden cable with red black shielded pair. Inputs black wire positive outputs red wire is positive. So pressure transmitter would be my analog input sinking and sourcing because the transmitter get both power and sends signal back along same wire through 4 20ma. Then the output would fire sending power to pressure control valve. Sourcing. Where I am now confused is on digital input sourcing. I thought digital input received the signal and digital outputs send out 24v. Analog outputs send out milliamps or millivolt usually. When I need better counting circuits I use sensor that use fiber optics and bring them back to an input card that understands fiber. Now I have to go back and relearn where I am lacking in my understanding sourcing syncing pnp npn digital inputs and outputs vs analog inputs and outputs

[@michaelcostello6991]

Nice explanation

[@TimWilborne]

Thank you

[@mohammedk1127]

hello there ; im talk about ( zelio or delta (low cost plc)) how can i recieve (4-20 ma) and how can i saving these data in register and export them by ethernet or serial output . and about module that i use to convert 4-20 ma to 0-10v or 0-5 v is ther any problem with real floating signal like (4.367 ma for example) i mean i want to keep this real signal and i want to get it like input with not approx reading regards

[@tonygonzales652]

Great video, thanks for the info.

[@TimWilborne]

Glad it was helpful!