PLC basic garage door program

Discussion in 'Automotive Electronics' started by julie saikia, Sep 22, 2018.

  1. julie saikia

    Thread Starter New Member

    Sep 22, 2018
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  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    That is a very basic circuit. Either of the UP/ DOWN buttons can be initiated, the energized side locks out the opposing direction while active. The respective L.S. ends the sequence.
    BTW, there is quite a bit more logic required for the average G.D. I wrote one once for a small Picmicro.
    P.S. the L.S. are not labeled.
    It is more an example of ladder logic than a garage door application.
    Example ladder circuits.
    Max.
     
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  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    To complete the labeling, the N.C. P.B. should is the mutual stop or Emer-Stop, the top L.S. is the UP L.S. , likewise the bottom one is the DOWN L.S.
    Max.
     
  4. julie saikia

    Thread Starter New Member

    Sep 22, 2018
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    Thanks for replying. I'm a complete beginner in PLC. I don't understand the action of NC 2CR when PB 1 is pushed.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    2CR as is 1CR are lock out contacts on relay 1CR/2CR that when one side is energized, they are used to disable the opposing side from operating, which would cause a conflict.
    IOW the two contacts are registering the state of the outputs 1CR/2CR.
    Max.
     
    Last edited: Sep 22, 2018
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  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Incidentally if this were a PLC program, the relay outputs 1CR and 2CR could be used to pick up the external motor relays, making the top two rungs superfluous.
    It looks more like a hard wiring diagram.
    Max.
     
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