Toggle Switch in PLC Ladder Logic using Counter


Write a PLC ladder logic program to design a toggle switch using only a single counter in order to convert a push button into toggle switch.

Toggle Switch in PLC

As per the given problem, we need the output to be controlled using a single push button i.e if the previous state of the output is low, on pressing the push button, the output turns ON, and vice-versa.

Toggle Switch in PLC Ladder Logic using Counter


It contains a simple holding circuit, in which an NO is connected in parallel to the “Toggle Switch” input, which in combination acts as a holding circuit.

The output Q0.0 “LED” is connected in series with the NC contact which is used for breaking the circuit.


As per the problem, the toggle switch is made using Counter. The counter is given the Input I0.0, which when pressed for the first time, holds the output Q0.0 and at the same, the counter is increased by one.

When the same “Toggle Switch” is pressed again the counter is incremented and the value of the counter becomes 2.

Since the preset value is also equal to 2, as per the interlock, as soon as the push-button is pressed and released for the second time the counter resets.

The toggle switch example ladder diagram from our Siemens PLC training course.

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