How to Convert a Basic Wiring Diagram to a PLC Program
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- Опубликовано: 17 мар 2019
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In this video, you will learn how to convert a basic wiring diagram to a ladder logic PLC program. This can be a very handy skill to learn, especially if you are converting a machine to PLC control.
Upgrading a machine to PLC control may seem like a daunting task. However, if you take your time and learn the basics, it can be an easily achievable task.
I will walk you through programming a very basic “stop-start” circuit for an electric motor. This should help you get a handle on some of the basics.
First, let’s look at our basic start and stop diagram. I like to start on the left and follow the line. Each line represents a wire that is connected.
L1 is our 120v hot wire. It will run straight to the normally closed Stop button labeled PB1.
From the other terminal on PB1, it runs to a normally open PB2 which is our Start button. From the other terminal on PB2, a wire connects to the A1 terminal on the Motor Starter Coil.
The A2 terminal runs to the normally closed overload auxiliary contact. The next wire runs from the other overload terminal to neutral.
The next line down shows how a motor starter stays energized. One wire needs to be connected to the input terminal of the start push button.
It will run to one terminal of the auxiliary contact set on the motor starter. This ensures power is on the auxiliary contact.
The second terminal of the auxiliary contact is connected to the output side of the start push button.
When the start button is pushed, the circuit is complete and the motor starter will energize. This closes the auxiliary contact and allows the operator to release the start button.
The motor starter will now stay energized until the stop button is pressed and the circuit opens.
Programming software is all different but similar. Most have a toolbox somewhere that you will drag your contacts and coils from.
Just like on the diagram, we start with the stop pushbutton. It will be represented with an examine OFF bit. These look like a normally closed contact.
Drag it to the first ladder rung and the program will place it to the far left. This will be a stop push button.
Next, drag an examine ON bit and drop it to the right of the first bit. This looks like normally open contact and will be the start push button.
And continue to complete your PLC programming logic according to this simple start-stop wiring diagram.
To wrap it up, to program a simple motor start-stop circuit, we need to read the electrical diagram from left to right and open our toolbox on the programming software.
You will be using the most common bits in the examine ON, examine OFF, and output coil or output energize.
Again, the language is sometimes different between manufacturers, but the symbols pretty well look the same.
The bits will represent normally open and normally closed inputs, and a single output. You will also need to use a branch around one bit. This is basically a parallel circuit and OR logic.
The start push button OR the auxiliary contact will energize the circuit.
I hope this video has been helpful in the transition from wiring diagrams to plc programming. This was a very basic program that can run a motor.
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Thanks! you changed my life in just 4 videos, i hope i can keep up with you
You are the best education canal on RUclips environment ever. Thank you so much that you have been giving a knowledge about PLC and basic mechanisms of automation industries to people.
Hi Peter,
Thanks a lot for your kind compliment! We are always extremely happy to hear such positive feedback! If you ever have any questions, feel free to reach out to us. Happy learning!
Perfect training example. Not overwhelming. Thanks.
Glad you liked it!
I have worked on VFD for 8 years as electrical professional. Your video gave clear idea of convertion to PLC-Good
Glad to hear that! Thanks for your positive feedback
Thank you realpars for educating us. Really a good work. I am regularly watching your videos all are clear and good.
You are very welcome, Mohamed! Great to hear.
Such a useful video on such a basic, yet essential topic! Thanks so much for explaining it step hy step! :D this kind of vídeos are really helpful for beginners like me
Great to hear! Thanks for your positive feedback!
Where is the next video
Follow RealPars on Instagram instagram.com/realparsdotcom/ for daily practical tips and tricks on Industrial automation and electrical engineering topics.
Good information.. How more in depth is the real pars course training?
WOW THANKS A LOT IM VERY VERY GRATEFUL FOR YOURE GREAT WORK.WISH U ALL THE SUCCES GUYS
What kind machine is that ?
Professional videos with super content ( free ) thanks for every second u spent to do this . Thanks Real pars team
Great to hear, Ahmed! You are very welcome. Happy learning!
Thank you,I always really happy to watch your videos to learn PLC, its really helpful
Great to hear that, Zeeshan! Happy learning!
It's an important video for those who want to learn PLC program. Thank you RealPars.
Happy to hear that! You are very welcome.
@@realpars Love you.
Very worthful video to those who are starting in PLC programming. The parallel contact to the Start Button is usually called "Seal-In" Contact.
Thank you, Melquiades!
I know it also as a "hold in" contact. The magnetic solenoid has been pulled down when activated by the closing of the start push button.
in the uk its known as a "latch"
This was so great. Really great. I enjoyed watching it and understood everything. Thanks
That's great to hear! Happy learning.
We need more videos like this videos
Thanks alot for great learning , lord information and good voice for learning English
You are very welcome, Sami! Great to hear that.
Muito obrigado pelo vídeo. Muito Top!!!!!.
Vou repassar para meus amigos que estão iniciando.
thanks for information with such a nice description
You are very welcome, Faizal!
Your stop puch button is NC type so Input %I0.0 will change the contact to No so you have to place NO contact in first so that NC is normally closed gives the input to %0.0 and the contact will change to NC which allows the circuit to complete .
Same remark for the overload contact. It opens when activated.
Can't wait fir the next video.
Great! :)
Thank you for once again helping technical people out in the field.
You are very welcome, John! Thanks for your support.
Good explanations and perfect representation thanks
Thanks a lot, Lazhar! We appreciate such support.
Amazing work guyz ! keep going
Thank you! Happy learning!
All your videos are interesting, at least for me. I'm just beginning in this. Greetings from Mexico.
Great to hear that, Francisco! Thanks for sharing.
It is possible to do it with the star delta ???
Good explanation
Thanks for this valuable sharing!
You are very welcome! Happy learning!
Thank you very much, i hope that was a Link for practicing and by in close to perfect learning .
Hi Mohammad,
Thanks for your comment!
We don't have a free software link to practice the newly gained knowledge. But, we do sell a variety of software and hardware in our online store. Including a sharply discounted TIA Portal software for €59.99 instead of the regular €2.4300.
Feel free to check that out over here shop.realpars.com/tia-portal-v16-6ES7822-1AE06-0YS0
If you have any questions, please let us know!
So easy to understand thank you
Great to hear that, Mary! Thank you.
Great tutorial video and verify informative for beginner. Thanks for sharing.
Glad to hear that, Kenny! Thank you for sharing.
great work, simple explanation superior presentation, still waiting for the following up video on how to match physical connection
Thanks for your support and anticipation to the follow-up course video!
Happy learning!
Thx for Your share!!
Thank you for that effort you help me to step in the way to my dream
Glad we could help! Keep it up :)
Thank you very much for this video. Please make a video about how to red electrical diagram.
Best wishes
Very helpful . Thank Thank you.
Happy learning!
Very good example!
Thank you, Bob!
Interruptor con permanencia de encendido ...y su pulsador de apagado ...❤👍amo la electricidad
Perfect explanation 💐
Thank you!
Hello,
nice channel, I think.
But me as an CAE- engineer would place the OL1- Contact right behind L1- potential, so I would be able to take the potential behind OL1 für other Controls as Hand-0-Auto or on site - remote.
;)
Hello Real Pars,
Thanks for all your videos, they are extremely helpful.
Kindly make some detailed videos on PLC, SCADA, VFD Control Panel with Design and Working. Hopefully you will upload it soon.
Thank you, Prateek! I will pass your request on to our creator team. Happy learning!
Interesting and easily explained. Please make plc programming on conveyor belt
Thanks for your comment, Himanshu! I will happily pass this on to our course developers. Thanks for sharing
Very use full tq Real parts
You're very welcome!
This is powerful man thanks
Thank you!
Thank you
Thank you so much buddy ♥️♥️
You are very welcome, Rajiv!
nice explanation waiting for next video
Thank you, Ganesh! Next week there will be a new video again! :)
Thank you so much for all your videos❤❤ . Can you please make a video based on the types of cables used for termination of different instruments on PLC
Hey!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
Your voice is perfect man
Thank you, Dennis!
Yeah, that it's right 😄😄😄❤
Very nice to understand.
Great to hear that, happy learning!
@@realpars Thanks.
Very nice explanation sir.
Glad to hear that!
Amazing thank you👌👌
You are very welcome!
Yes it was very educative
Glad to hear that!
Golden information
Thanks for your support! Amazing to hear that.
its good ,please bring more video
Thank you!
Thanks
Nicely explained
Thank you!
Thank you for your videos.
I'm confused about how the Start Button (PB2) causes the other branch (KM) to activate and how having a normally open switch to represent KM makes sense
Great question! When PB2 is pressed, you should be able to trace a complete circuit from L1 (Voltage Supply) to Neutral (N). That circuit goes through the coil in the motor starter KM. When the coil in KM is energized, it pulls in a magnetic contact block that closes a set of contacts, indicated by the switch KM that is wired in parallel to PB2. So, when PB2, the momentary pushbutton is released, the motor starter run contact, KM, keeps the circuit energized. When the stop pushbutton PB1 is pressed, the PB1 contact opens and the circuit is broken. The motor coil releases and the motor stops. When the motor stops, the KM run contact opens again, and you will need to press PB2 to start the motor again.
Very nice sar thanks for you
You are very welcome!
What's the name of the program that you use for programming the operation? Can you give us a link to install it ?
Your videos are awsome compadre gettings from Ecuador
Thank you, Miguel!
Very good n thanks sir
Thank you! Happy learning!
Such a useful video can u explain how do we synchronize generators through plc
I afraid, this is not a question that can be explained here and needs a complete course! It needs special instruments such as synchroscope to measure the synchronization of the voltage and frequency of the busbar and the generator. Relatively you should have special knowledge about these instruments and how they work in order to write the logic.
Awesome
Hi . This is my first video i have seen. I have a simple note to the plc diagram, if you used a simple Normally closed push button for stop button , then you need to make the logical stop button in the plc diagram to ( Examen ON ) not (OFF ) to make the diagram works .
That's a very good catch. If we assume no hardware changes as the control panel devices get wired to PLC inputs/outputs, the physical contact on the STOP button would be normally closed and open when pushed. As such, you would want the PLC code for the STOP button to be an open contact. The closed physical contact would hold the logic true at that point until the button is pressed.
Patrick Dowden ok. Practecally stop p.b is always normally closed therefore i said that. Thanks for replying.
Hi beginner here. What software do you use for this tutorial? Thanks for the useful info I learned a lot from it :)
Hi Jefrey,
Thanks for your comment! Happy to hear that.
Regarding your question, I am actually not sure about this as this is done by our graphic and animation department.
When will you upload another detailed video regarding the points we missed or should learn regarding the logic and stuff related to conversion
Thanks you
You are very welcome!
Take you!!!
helpful video dear.......
Great to hear that!
In Ladder program the Stop push button and the overload should be "examine on contact" because we have to check if they are closed before starting the Motor
I noticed that myself. I find this same error being repeated in several PLC ladder logic video's.
Good sir g
I couldn't be more appreative to www.realpars.com.
Thank you!
In my school I learned the circuit diagram is done in international European system and the ladder language is American system, which is the same but the first is done vertically and the ladder language horizontally.
Any videos on PLC logic for VFD control (start & stop, analog speed increase and discrease by HMI control) kindly provide video
Thanks for the topic suggestion, Devu! I will pass this on to our creator team! Happy learning.
thank you , why do we gave the same output address to the KM in the input and the other in the output ?
In S7 PLC's there are two memory areas allocated for inputs and for outputs. Each of these memory areas start at word 0. For instance, for inputs, the memory addresses are I0.0, I0.1, ...., I0.7, I1.0, etc. For outputs, the available memory area is Q0.0, Q0.1, ...., Q0.7, Q1.0, etc. Although the numerical part of the output and input tables are the same, they are distinct and do not overlap.
How did you guys make the animation on the basic wiring diagram (which program did you use?)
I have a school project where I have to make a animation witch is similar.
Hi there, we use Adobe Premiere for our animations. :)
RealPars Thank you ，sir . I also look for the software.
thx
Thankyou sr
You are very welcome, Wilberth!
I recommended you a Topic "Model predictive control"
Thanks for the topic suggestion! We will add it to the list!
FYI, this wiring diagram is European. North American wiring diagram the diagram is vertical instead of horizontal, hence called ladder diagram, where each line is called a rung. Also for the viewers, the Auxiliary Contact is often called holding contact, already mention in the video but just making it clear.
Liked the video!
Thanks for your comment and sharing your knowledge and experiences with us!
the stop and the overload contact should be a Normally Open contact at the PLC program due to the fact that the inputs will be True ,,because the contacts wired at the inputs are Normally Closed
Anyway , thanks for all the information you share at your videos :)
Thanks for sharing your thoughts, Mike!
Good
So Q0.0 Gose straight to the starter coil? You dont need a latch N/O 2,3 on the motor starter?
On the left-hand wiring diagram, there a motor latch (seal-in) provided around the start pushbutton by NO contact "KM", the designation for the motor starter coil. In the PLC logic equivalent, this same functionality can be provided by %Q0.0 in the branch around the start pushbutton input. If using the PLC to control the motor, yes, only the output %Q0.0 is wired to the motor starter coil in the field. The start and stop pushbuttons are wired directly to the PLC. In many cases, a NO auxiliary contact is brought back from the starter to allow the PLC to determine if the motor coil was actually pulled in. If not, after a few seconds, a command disagree alarm can be generated which may be used to stop the motor. Signals from a disconnect, fuse block, or overload package can also be brought into the PLC to monitor and control the motor. These "extra" signals cost extra to interface to the PLC, so often they are not done so except in critical applications.
When the stop-pushbutton and the thermal overload-contact are both normal clossed wired to the input's of the PLC you must use --| |-- instead of the -| / |-- for both of them.
Not necessarily. When you go on www.realpars.com they have explanations about why in a series of videos.
Connecting a normally open switch as a PLC input to 'stop' a motor is potentially dangerous. And for 2 reasons it is illegal.
1) PLC would fail to see the switch change state if it was faulty and the motor would continue to run
2) A broken wire to the stop switch would go undetected and allow the motor to be started with no means to stop the motor.
Very true. This is important in a real time application, since the stop pushbutton/ overload will appear open---using this very ladder logic (as it will be having a logic state 1 by because of presence of 24v). Except when using the plc simulation mode whereby all the bits are ,by default, not energized until checked.
Hi there,
Thank you for your precise comment.
You are actually right about the Normally Closed contacts in the ladder logic. As the Stop Push Button is Normally Closed, then we should consider it as an Open Contact in our "PLC Logic". Otherwise, the Stop Contact in our logic will prevent our motor from running.
@@realparsHi. I suggest that you publish a video clarifying something so fundamental and basic in PLC programming. Beginners may be left with a confusing idea when they have to program by themselves. That´s one of the first aspect of programming that I taught to my students. However, your videos are the most interesting. It´s a pity you didn´t take that consideration in this explanation. Thanks for teaching in such a clear and simple and animated way. Regards
Hi RealParks, thanks a lot for the videos. I am a beginner, please can you give the link or name of software use for wiring diagrams so that I practice it at home. Thanks for the great job one more...
Normally, design of wiring diagrams is done with AutoCAD Electrical or other CAD software, but there are a few "free" packages that I have found useful with my mentored young engineers. The first one is SmartDraw, which has a 7-day free period, and is very reasonably priced for a license. The other is SkyCAD, which has a 'perpetual" free version which I believe can do what you are looking for.
Great
Sir if possible then make a video how to draw wiring or control diagram...
Thanks for the suggestion, Syed! I will pass it on to our creator team.
that's great
Thank you, Joaquin!
thanks
You are welcome!
where can i buy the siemens PLC module so I can learn the actual programming and do some other diagrams to test?
Hi there,
Thanks for asking! You can check out the company in your area through the link I shared. They sell Siemens PLC and I/O cards. Here's the link: Siemens PLC and I/O Cards. us.rs-online.com/view/search?keyword=Siemens%20%20PLC
Also, you have the option to grab the Siemens TIA Portal programming software for free. It'll work for 21 days. You can download it from the Siemens website here: Siemens TIA Portal Software
support.industry.siemens.com/cs/document/109784440/simatic-step-7-incl-safety-s7-plcsim-and-wincc-v17-trial-download?dti=0&lc=en-US
Happy learning from RealPars!
Great sir, what is name of your software please
Merci beaucoup à votre équipe
Funny how the "Overload" OL1 is treated as normally closed, when in reality they are normally open. But engaged (closed) at an active system... when the pushbutton is shown as normally open. Besides that, the overload is normally the first item in the function tree, as it is supposed to protect the circuit below, relative to a short circuit early in the circuit. Because imagine the scenario where the wire gets loose at after the "Motor Starter" in a normally neutral grounded system.
I think the overload there he means the device thats the plc (contacts) are protecting
@@felipequintela3254 What i mean is that if a wire gets loose before or after the OL, the circuit can still remain active, if the loose wire gets grounded (bypassing that OL auxiliary contact). It will not matter if the OL triggers. Only if the system is grounded and not isolated. They are mostly grounded.
Circuit is not optimal, as the OL contact is after the relay...
thank br
Our pleasure!
Its very helpfull ...what is the module of this API automat ???
Hey Nasser, which module exactly you mean?
@@realpars i mean the kind of plc
@@Funny_TV_Dz The brand or the model of the PLC does not really matter in converting a wiring diagram to a PLC program. The language which is used is Ladder programming. This is one of the standard languages which is applicable in any kind of PLC brand.
By the way, the software application interface here is TIA Portal v14 which is a Siemens product. You can use any kind of Siemens PLCs such as S7-1500 or S7-300 series.
Thank you so much for this information ...where are you from ?
Plz make other diagram aloso like this
Thanks for the suggestion, Ketan! I will surely pass this on to our creator team.
hey iam starting whatching all your video becouse this is the area a i d like get knowlege ..
Great to hear that! Keep up the learning curve!
Yes me too, the lecture so great. Very clear and interesting. I have much experience in the " old method" but, PLC is very new. Thank you very much sir.
Haii realpars team,
I want to learn about FAT, SAT test in automation
Kindly update it...
Thanks for the topic suggestion, Mohamed! I have gone ahead and passed it on to our creator team.
I really enjoyed all of your videos. Eagerly waiting for this FAT, SAT test video. I hope you'll do it soon.
Thank you realpars & team
you always have to program the Stop buttons as a normally open contact in the program. If there is a fault you will never be able to turn off the motor
Yes, this is how the PLC logic should be programmed for a fail-safe implementation of a wired stop pushbutton. The issue is in understanding how the field device is wired and how it is represented in the PLC. If you have a physical stop PB, the contacts should be NC, meaning the PLC input is a '1' when not pressed, '0' when pressed or the wire breaks. In this case, the PLC element for the stop PB in the ladder must be NO. HOWEVER, if the logic is driven by a software switch, then th stop PB is '0' when not "pressed' and '1' when pressed, and the ladder, in this case, the stop PB would use a NC contact. This is why you need to understand how the system is wired and which devices are physical and which are virtual (software).
what is the name of the software you used?
Thank you for your question, Jethro. Our animation department makes our videos using a number of programs and graphic design tools. The way we do this is one of our trade secrets. If you are interested in software to create electrical ladder diagrams, EDraw Max is a good place to start (edrawmax.com). They have a free trial version.
but HOW CAN I GET THIS SOFTWARE S7-300 and practice in home
Hi Benjamin,
Below are some links through which you can download different versions of STEP7.
STEP7 V5.6: sie.ag/2Hw6UKy
STEP7 and WinCC V15: sie.ag/2Eo3LKJ
Hopefully, this is helpful! Happy learning!
Does anyone know a software to make the wiring diagrams like that?
Normally, design of wiring diagrams is done with AutoCAD Electrical or other CAD software, but there are a few "free" packages that I have found useful with my mentored young engineers. The first one is SmartDraw, which has a 7-day free period, and is very reasonably priced for a license. The other is SkyCAD, which has a 'perpetual" free version which I believe can do what you may be looking for.
I think there is a problem of NC contact of stop button. If the NC contact is used, the plc program will not run because NC then changes to NO.
Pham Quoc Phuong NC contact is required condition, in the case of a line break, motor will stopped. Read about this on a education forums