Is there a systematic way to get solution in PLC programming?

Discussion in 'Homework Help' started by anhnha, Dec 17, 2013.

  1. anhnha

    Thread Starter Active Member

    Apr 19, 2012
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    I am struggling with ladder diagram for traffic light. Is there a systematic way to get the solution?
    I don't know if Karnaugh map works here. I have searched a lot but there is not a complete guide on this.
     
  2. odinhg

    Active Member

    Jul 22, 2009
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    Are you familiar with the finite-state machine? It might help you get it done.
     
  3. anhnha

    Thread Starter Active Member

    Apr 19, 2012
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    Yes, not good but I have used it many times. I have seen flow charts used in some books.
    Did that what you mean?
    By the way, can I use karnaugh map here?
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    When one can end up with hundreds of rungs on a ladder diagram it would become difficult to envisage how a Karnaugh map would assist in the design. Add the complexity of timers, counters, computational blocks and HMI's and you have a grander design to accomplish. The matter of knowing the required system state at the completion of each execution cycle is a key factor as is the verification & testing of those states.
    Experience is therefore important and also studying how other designers do this work is helpful. PLC manufacturers may offer training courses.
     
    Last edited: Dec 18, 2013
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    I also use PLC in my job and I never see any PLC programmer witch use karnaugh map.
    All you need is experience and split the "problem" into small pieces.
     
  6. anhnha

    Thread Starter Active Member

    Apr 19, 2012
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    Thanks everyone.
    I thought that there is a systematic way to solve most of problems. I saw my professor struggling for a while to complete a ladder for traffic light. That made me wonder how can I do it well as even my prof also had to go through it four or five times before got it right.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    One often recommended way to start is the flow chart method.
    Max.
     
  8. alfacliff

    Well-Known Member

    Dec 13, 2013
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    one way to symplify the trafic control light timer is to use the master clock. a simple store and compare to control whitch light is on. much easier than using a bunch of timers. just run a counter off the 1 second clock, then compare the count with presets to determine the output to turn on.
     
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