Programmable Logic Controller (PLC) Questions and Answers – 7

Programmable Logic Controller (PLC) Questions and Answers 

Suppose we have a PLC connected to three pushbutton switches as shown in this illustration:

PLC Questions - 1

X1 to X4 : Digital Inputs

Y1 to Y4 : Digital Outputs

Determine the switch actuation statuses (i.e. pressed versus released) given the “live” display of the ladder logic program shown here:

PLC Ladder Logic for Push button

Answer :

Necessary switch statuses:

  • Switch A = released
  • Switch B = released
  • Switch C = pressed

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Credits : by Tony R. Kuphaldt – under CC BY 1.0

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2 thoughts on “Programmable Logic Controller (PLC) Questions and Answers – 7”

  1. problem # 7:

    “Determine the switch actuation statuses (i.e. pressed versus released) given the “live” display of the ladder logic program shown here:”

    The correct answer should be
    Switch A = pressed
    Switch B = pressed
    Switch C = released

    If your question asked to provide the appropriate push button states to turn lamp Y1 on, then your answer would have been correct (unless I am overlooking something that I did not catch)

    Reply

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