Ladder Logic for Stair-Case wiring using Toggle Switches

Design Ladder Logic for Stair-Case wiring using two Toggle Switches in programmable logic controllers (PLC).

I0.0 & I0.1 : Input toggle switches.
Q0.0 : Output signaling device(bulb, motor etc.)

Ladder Logic for Stair-Case wiring

This ladder logic of stair-case wiring works on the X-OR logic i.e, Y is (A.B^) + (A^. B)

Suppose initially only I0.0 is pressed and I0.1 remains open physically as shown then the upper branch of rung 1 goes TRUE and Q0.0 gets energized.

Now , if I0.0 is also pressed then it will make its interlock N-C contact I0.1 to go open and as a result Q0.0 de-energizes .

Again, if switch I0.0 is pressed it will also make its interlock contact I0.0 in parallel branch to go again N-C , which in turn makes the parallel branch logic true and Q0.0 again energizes but if the I0.1 input is also pressed again the logic goes FALSE and Q0.0 again de-energizes. This is the basic concept of an X-OR logic gate.

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