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Trying to learn...

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  • Trying to learn...

    Hello everyone, Thank you for the opportunity to be here.

    Honestly, I feel like a dummy because I just cannot get the 'lightbulb moment" with Ladder Logic. I'm a couple of classes in, and just when I think " ah.. that's it " ... the bubble bursts! Any help or advice would be so very gratefully received..

    Thank you all,
    Best wishes.

  • #2
    From experience, I know If you purchase a Click, a Do-more, or Productivity PLC, it includes a card with a code for 30 days free training from interconnecting automation. It's a good place to start.
    If you've done the very best you can, worrying won't make it any better - Walt Disney


    • #3
      When I first started with PLCs it was developing a clear understanding of the scan. Once I had that everything else seemed to slip in to place (or at least be a lot more understandable).



      • #4
        Get on the youtube.
        Look for Ron Beaufort PLC Bootcamp videos. They are a scaled-down version of his classes but are very enlightening!


        • #5
          Hello all!
          Wow - thank you for our words of encouragement and advice. I am humbled.
          What irks me most is that I can play Chopin / Bach etc, on the piano from memory, yet I can't find the right way to ' Think ' about Logic. Ugh!


          • #6
            It is not so much about memorizing as gaining an intuitive understanding. Do your classes include hands-on experience using and applying PLC's? In my classes, once students see things happening, the operation is more meaningful.
            I also see it helpful to understand and have experience with pushbuttons, relays, etc. before hand.
            Last edited by johnaden; 11-14-2017, 05:34 PM.
            Automation & Electronic Controls

            Design, Build, Repair, Training


            • #7
              I forgot to mention, if you download (it's free) the Do-more designer software, you can test PLC code without even having a PLC.
              If you've done the very best you can, worrying won't make it any better - Walt Disney


              • #8
                Thanks again everyone. I appreciate you all taking the time to reply and offer your well earned advice.
                I believe my issue is Not having an understanding of the absolute basics..the core basics of Logic programming. It's like I'm trying to build a house on no foundations ( or slab, as you say ) .. oh, I should tell you that I am originally from the UK, living in Houston.. that may explain some of the ways that I type things!

                Genuinely.. I cannot sleep for tying to figure this out!

                Best wishes to you all,


                • #9
                  Do you understand basic wiring? For example, how the switch on the wall is wired to the lights in the ceiling?
                  If you've done the very best you can, worrying won't make it any better - Walt Disney


                  • #10
                    Good to see another newbie, my first post and I'm further behind you big harley chop, I haven't started learning ladder yet. Just starting out on a home project and wanting to learn, great suggestions by others, thanks.


                    • #11
                      Originally posted by big_harley_chop View Post
                      ...I believe my issue is Not having an understanding of the absolute basics..the core basics of Logic programming...
                      Think of the vertical line on the left as power (its always turned ON). Then there are basically two halves of the screen, the left side and the right side. The left side is where you put contacts (e.g. light switches). These contacts will pass power from the power rail toward the right side. On the right side is where you put things you want to turn on (e.g. a light bulb). In my picture, if X0 is switched ON, then Y0 will turn ON. X0 is an input & Y0 is an output. If X0 is switched OFF, then Y0 will turn OFF. Simple. So to make this work in the real world, you would literally wire a physical switch to the X0 input on the PLC and wire a physical light bulb to the Y0 output of the PLC.

                      The PLC itself starts at the top of your program and scans left-to-right, top-to-bottom conceptually reading and writing inputs/outputs as it goes. That's not how it actually works, but that's how you can imagine it working.

                      The way it actually works is, the PLC reads the state of all its real-world inputs and stores them in its image register (e.g. in my example, the state of X0 is read from the physical switch and stored as ON or OFF). Then the PLC scans its logic. Let's say it sees X0 was ON. Then when it scans the logic it turns Y0 image register bit ON. After the PLC finishes scanning all its ladder logic (i.e. reaches the bottom), then it writes the output image register to the real world output thus turning the actual light bulb ON. Then it repeats this cycle. This is called a PLC scan; read inputs, scan logic, write outputs, repeat indefinitely.

                      Those are the very basics. Hope this helps.
                      Attached Files
                      Greg Kiser
                      Hos Engineering, Inc.
                      This isn't all true.


                      • #12
                        Check out, it's a great forum where I posted a lot of basic questions. Just be sure to provide the PLC model you are working with!