Thank you. I've been self learning very basic logic stuff and I've been trying to find out very clear information about how PLC card types and PNP and NPN sensors actually work in practice. Now I'm finally pretty much 100 confident how they're supposed to work. Very good video, thank you 👍👍
Literatures and PLC manufacturers differ from one another when it comes to the concepts of sinking and sourcing. The important thing is that you have to maintain the potential difference of 24V between digital input and common terminal. In many PLCs, we can connect either 0V or 24V to common terminal and opposite of that (24V or 0V) must be connected to digital input. It is better to refer installation guides of PLCs to decide wiring connections. Some PLCs even have jumpers to switch from sinking to sourcing type wirings and vice-versa.
Every circuit has a power source and a load. This this case, the input card is the load on the circuit. It’s the device that regulates the amount of current the flows through the circuit. Sourcing or sinking just determines whether you switch the + side of the power supply or the ground side of the circuit. The circuit works the same when current flows but it has ramifications that are important to note. For instance, let’s take the sinking input. You have +24v going out to the field and when the switch out there closes it comes back, through the input card (load) to ground. Now let’s say you accidentally ground out one of those field wires. It could me anything. A tech could drop on and hit the metal conduit. The conduit can be damaged, or the switch can fail and become grounded. If you do that to the +24v wire, then you immediately short the power supply. If you do it to the return wire, then you short the power supply when the switch closes. Either one can take down the whole control system unless you put in overload protection. Now, in a sourcing input card. The two field wires are placed in the circuit AFTER the load (input card). If you short the wire coming from the card to ground, the input goes active immediately. If you short the wire after the switch (going to ground) then the input goes active after the switch is closed. This makes sourcing inputs more able to deal with failure modes. Unfortunately, sourcing type inputs can be trickier to troubleshoot and the tech definitely needs to know it’s a sourcing input card. Sinking cards are by far the most common found in the US. I believe that’s because they more closely resemble how most electric circuits work and so, are easier to envision for troubleshooting and for designers.
Such an amazing explanation ! And yes; we faced such ground in GE Speedtronic Control System and it took us some time to figure out the problem ... Thanks for your detailed comment I already screenshot it as a reference for me and for my fellows
Thanks a million times for your informative and detailed videos i became literally a great follower to all your automation videos ans also literally video by video
Excellent video, very didactic and applicative, could you upload a video of the same thing with analog inputs, it would be very helpful since I am trying to connect a sinking-type analog instrument and I want to know if I have to modify the connection of the module to a sourcing type
Great suggestion! I will happily pass this on to our course developers, hopefully they are able to create a video course on this in the near future. Thanks again for sharing and happy learning!
I am new to this branch of engineering. Could you please help me on my question. How does the CPU detect which of its many input is receiving a 24V DC? Is it by 0s and 1s? Does each input have separate wirings going to the CPU? Thanks a lot.
Hi there. Thanks for your question. You've got the right idea about the 1s and 0s. There are no actual connections between the input modules and the CPU. Each input status is stored in the PLC's RAM memory as a 1 or a 0, depending on its condition. The CPU uses this memory information to perform the logic required by the PLC program.
Hi @Ra Gho. Thanks for your question. We use conventional current flow terms when describing current flow. Conventional current flows from positive to negative. If you are referring to electron current flow, then you are correct.
Hi. Thanks for your question. It really depends on what you want to switch with your sensor. Do you want to switch ground/return or supply voltage? It also depends on the input module itself. If your module is a sinking type, you need PNP sensors. If your module is a sourcing type, you need NPN sensors.
Hello @t4c4. Thanks for your question. Let's assume our Power Supply voltage is 24VDC and the sensor is in the closed, or low resistance state. There will be 24 vdc at the Sinking plc input terminal and 0V at the Sourcing plc input terminal. Interestingly, with the sensor in the open, or high resistance state, the voltages will be opposite.
so if i have plc D.I. sourcing and i measure the voltage in each side of the switch(off state). what would be the reading? 24VDC? given 24 vdc is the plc
Hi @nayrbs world. Thanks for your question. If I understand you correctly, you are referring to an open passive SPST switch connected to an input of a sourcing digital input card. You will measure 24 volts on the switch terminal connected to the digital input terminal of the module. If the switch is open, there will be 0v on the other side of the switch.
i mean if i will use a switch with a (Normally open & normally closed switch SPDT) i wire a normally open to a d.i. sourcing plc. when i put the (+) leads of my multimeter to N.O. then (-) to common of that switch at idle state. what would be the reading in my multimeter. the same as what will be the reading when in NC state. thanks real Pars
Hi, I am planning to power up my Digital Inputs and Analog Inputs Extension module with 24V DC from PLC 24V DC Supply (500mA). Is it okay to do this? For the PH meter I use AC source, Flowmeter I use other DC Supply, and the pt100 temp sensor I use two wiring transmitter
Hi Chickenz. It's common to connect input devices to the 24 v power supply. But, you need to be cautious so as not to overload the power supply. Not knowing what you have currently connected to the power supply, it is not possible to determine the current draw. You might have to do a bit of homework to find current draws for your connected devices. As for the PLC inputs themselves, they draw very little current. I'm, sorry but I don't know what you mean by "Analog Extension module". Can you elaborate please?
@@realpars Currently I have PLC unit with 16 DI and 16 DO and Analog extension module with 4 AI. This analog module also requires 24V DC Supply. For the PLC it uses AC source and have 24V DC Supply Out. Thx
Stupid question. At my work it seems to be pretty much standard for all different manufacturers to use PNP sensors in their devices. But why does both still exist in industry? Is it simply backwards compatibility for older equipment or does NPN offer great benefits in some configurations? Oh and more, does ie. Siemens CPU's support to plug in both type of input cards simultaneously? I'd assume they would, though wiring would be great pia and very misleading to people who wouldn't notice that odd configuration.
Hi jothain. Both still do exist in the industry for a number of reasons. Your question is excellent and has appeared a few times for this video. If you scroll down and read through the comments, you'll see many responses from us and also other viewers. Siemens PLCs have the ability to have both sinking and sourcing modules at the same time. This is true for most PLC vendors as far as I know. And you are correct when you say it could be misleading and possibly create some errors dues to incorrect wiring faults.
@@roseelectronics4582 We can offer you industrial products like Module, PLC, LCD panel,HMI,VFD,CNC spindle,CNC accessories,servo system, stepper system etc.
Hi @Kurt Matchitt. Thanks for your question. Quick answer - No, the terms sinking and sourcing are only used when referring to digital inputs and outputs. We can expand on that answer if you would like more detail. Just let us know by replying.
Hi Mustafa, Great to hear your motivation in regard to learning PLC Programming. Our course library is specifically designed in a way where it provides all the tools needed for beginners to evolve into an advanced level through our hands-on courses. Feel free to browse through our course library to see all the different topics we are covering. bit.ly/30AVJaR Just to let you know, that we also have a free course on PLC Hardware bit.ly/2XnnUrF If you are interested, you will obtain full access to our complete course library (400+ video courses) by subscribing to either our monthly package for €22.12 a month or our yearly package for €159.28,-. learn.realpars.com/checkout/subscribe/receipt Additionally, you will have access to our Technical Team - consisting of high ranking engineers with a lifetime of experience - who are here to help you out with any questions you might have along the way! Hope this helps! If I can be of any further assistance, please let me know - I’m more than happy to help!
So with that in mind it's easy to remember a NPN card is recieving the current and a PNP card is the source of the current. If your like me a bit dyslexic you need these little rhymes to stick things in your head
@@danielkoryciak2357 Sometimes a control system is setup with sourcing PLC inputs as a design choice, but the main reason I have seen it used is when some of your digital field devices only support NPN outputs. Some rotary encoders, reed switches or other devices are not always available in a PNP output in the brand and size you want. In this situation you either need a converting relay to change the device output polarity to suit a sinking input, or to use a sourcing input setup.
I don’t get what the point is in having two different types? I feel like plcs are overly complicated for absolutely no reason what so ever it could all be done so much easier than the way it is
Hi @Bob Smith. That's a great question. Thanks for reaching out. Bottom line, it comes down to what voltage level is required. A sourcing input or output circuit provides the necessary voltage for the circuit. A sinking input or output circuit provides the necessary ground for the circuit. I'm sorry to hear that you think the graphics and illustrations are overly complicated. We do our best to simplify concepts for our viewers. Any modification suggestions are appreciated.
@@realpars no I didn’t mean your video was overly complicated I meant plcs in general . They can be done in a much easier way than they do them but they like making it harder for people for some reason
I'm working as an automation engineer. This video is very nice, well explained.
Glad to hear that, Kevin! Happy learning.
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Best automation teacher on UA-cam thank you 😊 RealPars 😎
Thank you very much!
Thank you. I've been self learning very basic logic stuff and I've been trying to find out very clear information about how PLC card types and PNP and NPN sensors actually work in practice. Now I'm finally pretty much 100 confident how they're supposed to work. Very good video, thank you 👍👍
Glad it was helpful, Jothain! If you have any questions along the way, please feel free to contact me at any time!
Do you need PLC or another products?
Do you need PLC or another products?
@@stevenlee5755 are you going to spam me how many times about this? 🤣
@@jothain Oh，I am sorry ,,won't disturb you again ,
Literatures and PLC manufacturers differ from one another when it comes to the concepts of sinking and sourcing. The important thing is that you have to maintain the potential difference of 24V between digital input and common terminal. In many PLCs, we can connect either 0V or 24V to common terminal and opposite of that (24V or 0V) must be connected to digital input. It is better to refer installation guides of PLCs to decide wiring connections. Some PLCs even have jumpers to switch from sinking to sourcing type wirings and vice-versa.
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Do you have any notes to understand in details?
These lectures are the best!!! Thank you, RealPars team!!!
Glad you like them! Thanks for your support, Alejandro!
@@realpars Thanks to YOU, guys!!! Keep rocking!!!
Thank God. I've been struggling with this concept for years.
Amazing, clear crystal explanation😃❤
Glad you think so!
Thank you so much. I came to class a little late and missed the lecture on this. This helps so much! Not hard to understand at all.
Glad it was helpful! Always feel free to let us know if anything is unclear.
Happy learning!
Every circuit has a power source and a load. This this case, the input card is the load on the circuit. It’s the device that regulates the amount of current the flows through the circuit. Sourcing or sinking just determines whether you switch the + side of the power supply or the ground side of the circuit. The circuit works the same when current flows but it has ramifications that are important to note.
For instance, let’s take the sinking input. You have +24v going out to the field and when the switch out there closes it comes back, through the input card (load) to ground. Now let’s say you accidentally ground out one of those field wires. It could me anything. A tech could drop on and hit the metal conduit. The conduit can be damaged, or the switch can fail and become grounded. If you do that to the +24v wire, then you immediately short the power supply. If you do it to the return wire, then you short the power supply when the switch closes. Either one can take down the whole control system unless you put in overload protection.
Now, in a sourcing input card. The two field wires are placed in the circuit AFTER the load (input card). If you short the wire coming from the card to ground, the input goes active immediately. If you short the wire after the switch (going to ground) then the input goes active after the switch is closed. This makes sourcing inputs more able to deal with failure modes.
Unfortunately, sourcing type inputs can be trickier to troubleshoot and the tech definitely needs to know it’s a sourcing input card.
Sinking cards are by far the most common found in the US. I believe that’s because they more closely resemble how most electric circuits work and so, are easier to envision for troubleshooting and for designers.
Thanks for sharing your knowledge and experiences with us! We always appreciate such in-depth comments.
Do you need PLC or another products? topstock.aliexpress.com/store/1155094
Such an amazing explanation !
And yes; we faced such ground in GE Speedtronic Control System and it took us some time to figure out the problem ...
Thanks for your detailed comment I already screenshot it as a reference for me and for my fellows
Thank you for this!!!! really helped me understand this better than my professor's instruction. Subscribed
Awesome, thank you!
Mechatronics engineering student here. Your videos are very helpful
Amazing! We're happy to receive such positive feedback!
Feel free to leave us any questions you might have. Happy learning!
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Thanks a million times for your informative and detailed videos
i became literally a great follower to all your automation videos ans also literally video by video
Great to hear that! Thanks for sharing and happy learning!
Finally, I got it. Thanks for your video.
Glad it helped! You're more than welcome, and always feel free to leave us any questions if anything is unclear.
Happy learning
Excellent. Very clear explanation. Thank you.
Glad it was helpful!
Very good explanation better then academic ones
Thank you, Genghiz!
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Excellent video, very didactic and applicative, could you upload a video of the same thing with analog inputs, it would be very helpful since I am trying to connect a sinking-type analog instrument and I want to know if I have to modify the connection of the module to a sourcing type
Great suggestion! I will happily pass this on to our course developers, hopefully they are able to create a video course on this in the near future.
Thanks again for sharing and happy learning!
Great video! I have never seen such a nice explanation! Thank you!
P.S. Liked and subscribed
Awesom, thank you!
Thank you for this video...
Thanks for your kind words!
Happy learning🎉
Beautiful presentation
Thank you, Faizal!
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After several tutorial I found sinking or sourcing this one I understand
Very nicely explained
Thank you!
I am new to this branch of engineering. Could you please help me on my question. How does the CPU detect which of its many input is receiving a 24V DC? Is it by 0s and 1s? Does each input have separate wirings going to the CPU? Thanks a lot.
Hi there. Thanks for your question. You've got the right idea about the 1s and 0s. There are no actual connections between the input modules and the CPU. Each input status is stored in the PLC's RAM memory as a 1 or a 0, depending on its condition. The CPU uses this memory information to perform the logic required by the PLC program.
@@realpars I understand it now. Thanks
isn't that current arrow reversed? Sinking current goes out, and sourcing current flows in. please help me if I misunderstood the whole video.
Hi @Ra Gho. Thanks for your question. We use conventional current flow terms when describing current flow. Conventional current flows from positive to negative. If you are referring to electron current flow, then you are correct.
You are almost right. Positive side (greater potential) goes into PLC if the device is a sourcing device.
Thank you Sir,This is very helpful video.
You're very welcome!
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Your videos are awesome. Videos are created in such a way that automation concepts are very easily understandable..keep up your good work👍
Thanks a million for your positive feedback! We always appreciate such kind comments.
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Great video 💯
Glad you enjoyed it! Thank you for sharing
Sir what are the condition under which we use npn or pnp sensors
Hi. Thanks for your question. It really depends on what you want to switch with your sensor. Do you want to switch ground/return or supply voltage? It also depends on the input module itself. If your module is a sinking type, you need PNP sensors. If your module is a sourcing type, you need NPN sensors.
when sensor is in closed state.
what will be the voltages in sourcing and sinking plc inputs?
Hello @t4c4. Thanks for your question. Let's assume our Power Supply voltage is 24VDC and the sensor is in the closed, or low resistance state. There will be 24 vdc at the Sinking plc input terminal and 0V at the Sourcing plc input terminal. Interestingly, with the sensor in the open, or high resistance state, the voltages will be opposite.
@@realpars Thanks
So if a plc common input or output has positive, then it’s sinking? A negative common would be sourcing? The field device being the opposite.
Hi Daniel Juneau. Yes, good summary in a nutshell. Thanks.
Thank you .. very informative
You're welcome
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Thank you very much!
You're welcome! Happy learning
DC current flows from negative to positive poles.
Thanks Sir 👍
You're very welcome!
so if i have plc D.I. sourcing and i measure the voltage in each side of the switch(off state). what would be the reading? 24VDC? given 24 vdc is the plc
Hi @nayrbs world. Thanks for your question. If I understand you correctly, you are referring to an open passive SPST switch connected to an input of a sourcing digital input card. You will measure 24 volts on the switch terminal connected to the digital input terminal of the module. If the switch is open, there will be 0v on the other side of the switch.
i mean if i will use a switch with a (Normally open & normally closed switch SPDT) i wire a normally open to a d.i. sourcing plc. when i put the (+) leads of my multimeter to N.O. then (-) to common of that switch at idle state. what would be the reading in my multimeter. the same as what will be the reading when in NC state. thanks real Pars
Good explanation
Thanks a lot, Johan!
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Very nice 👍👍👍
Thanks a lot, Abid!
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Hi, I am planning to power up my Digital Inputs and Analog Inputs Extension module with 24V DC from PLC 24V DC Supply (500mA). Is it okay to do this? For the PH meter I use AC source, Flowmeter I use other DC Supply, and the pt100 temp sensor I use two wiring transmitter
Hi Chickenz. It's common to connect input devices to the 24 v power supply. But, you need to be cautious so as not to overload the power supply. Not knowing what you have currently connected to the power supply, it is not possible to determine the current draw. You might have to do a bit of homework to find current draws for your connected devices. As for the PLC inputs themselves, they draw very little current. I'm, sorry but I don't know what you mean by "Analog Extension module". Can you elaborate please?
@@realpars Currently I have PLC unit with 16 DI and 16 DO and Analog extension module with 4 AI. This analog module also requires 24V DC Supply. For the PLC it uses AC source and have 24V DC Supply Out. Thx
Stupid question. At my work it seems to be pretty much standard for all different manufacturers to use PNP sensors in their devices. But why does both still exist in industry? Is it simply backwards compatibility for older equipment or does NPN offer great benefits in some configurations? Oh and more, does ie. Siemens CPU's support to plug in both type of input cards simultaneously? I'd assume they would, though wiring would be great pia and very misleading to people who wouldn't notice that odd configuration.
Hi jothain. Both still do exist in the industry for a number of reasons. Your question is excellent and has appeared a few times for this video. If you scroll down and read through the comments, you'll see many responses from us and also other viewers. Siemens PLCs have the ability to have both sinking and sourcing modules at the same time. This is true for most PLC vendors as far as I know. And you are correct when you say it could be misleading and possibly create some errors dues to incorrect wiring faults.
Do you need PLC or another products?
Good day sir ..can you explain ..how vs motor working principle. .
Hi Jasper!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
Thank you very much sir .. I'll wait for your video.. Good Bless
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thank you
You're very welcome!
Nice work!
Thank you!
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@@stevenlee5755 yes I do, what do you have to offer sir?
@@roseelectronics4582 We can offer you industrial products like Module, PLC, LCD panel,HMI,VFD,CNC spindle,CNC accessories,servo system, stepper system etc.
@@roseelectronics4582 various brand PLC and another industrial product ,such as servo motor ,gearbox,VFD ,and so on
Hello, i really like your videos, i'd like to know (IF possible) what program do you use to make those great animations?, Keep up the good work :D
Hi there,
Thanks for your kind comment!
I am actually not sure about this as this is done by our graphic and animation department.
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Great Sir
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@@stevenlee5755 Send Me Contact No
Can you have sinking and sourcing Analog inputs?
Hi @Kurt Matchitt. Thanks for your question. Quick answer - No, the terms sinking and sourcing are only used when referring to digital inputs and outputs. We can expand on that answer if you would like more detail. Just let us know by replying.
Great explanation!!
Glad it was helpful!
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Sinkn(pn) like sinking.
PuNP up power source.
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what about misubishi PLC?
for input signal, sensor is device 1
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Wow!
Please someone need to assist me, i need long time tia Portal v18 software. How can i go about it for am tired of using trial version
Thank you for your comment! Have you tried purchasing it from your local TIA Portal seller?
@@realpars I don't even know anywhere to get it, I was thinking is gotten from online
Helo how i can take PLC cources from u?
Hi Mustafa,
Great to hear your motivation in regard to learning PLC Programming.
Our course library is specifically designed in a way where it provides all the tools needed for beginners to evolve into an advanced level through our hands-on courses. Feel free to browse through our course library to see all the different topics we are covering. bit.ly/30AVJaR
Just to let you know, that we also have a free course on PLC Hardware bit.ly/2XnnUrF
If you are interested, you will obtain full access to our complete course library (400+ video courses) by subscribing to either our monthly package for €22.12 a month or our yearly package for €159.28,-. learn.realpars.com/checkout/subscribe/receipt
Additionally, you will have access to our Technical Team - consisting of high ranking engineers with a lifetime of experience - who are here to help you out with any questions you might have along the way!
Hope this helps! If I can be of any further assistance, please let me know - I’m more than happy to help!
@@realpars thank you dear
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@@stevenlee5755 PLC
So with that in mind it's easy to remember a NPN card is recieving the current and a PNP card is the source of the current.
If your like me a bit dyslexic you need these little rhymes to stick things in your head
Thank You!
But When we use sinking and sourcing.
Somebody can give example for a life 😌?
In most cases, we use sinking, so when we use sourcing?
@@danielkoryciak2357 Sometimes a control system is setup with sourcing PLC inputs as a design choice, but the main reason I have seen it used is when some of your digital field devices only support NPN outputs. Some rotary encoders, reed switches or other devices are not always available in a PNP output in the brand and size you want. In this situation you either need a converting relay to change the device output polarity to suit a sinking input, or to use a sourcing input setup.
Do you need PLC or another products?
Do you need PLC or another products?
I don’t get what the point is in having two different types? I feel like plcs are overly complicated for absolutely no reason what so ever it could all be done so much easier than the way it is
Hi @Bob Smith. That's a great question. Thanks for reaching out. Bottom line, it comes down to what voltage level is required. A sourcing input or output circuit provides the necessary voltage for the circuit. A sinking input or output circuit provides the necessary ground for the circuit. I'm sorry to hear that you think the graphics and illustrations are overly complicated. We do our best to simplify concepts for our viewers. Any modification suggestions are appreciated.
@@realpars no I didn’t mean your video was overly complicated I meant plcs in general . They can be done in a much easier way than they do them but they like making it harder for people for some reason