Latching Cercuit (Controlling The motor by pressing Start Stop Button)

Latching Circuit for Motor Control – Ladder Logic Application

Objective:

Control a motor using a momentary Start and Stop push-button setup. Once the motor is turned ON using the Start button, it remains ON until the Stop button is pressed—even if the Start button is released.

Working Principle:

• Start Button (I0.0): When pressed, it activates the motor.

• Latching Logic: Keeps the motor energized using feedback from the output coil (Q0.0), forming a memory loop.

• Stop Button (I0.1): Interrupts the circuit and stops the motor.

I/O Address Mapping

Device	Address
Start Button	I0.0
Stop Button	I0.1
Motor Output	Q0.0

Ladder Logic Program

 Explanation:

• Rung 1 activates Q0.0 (Motor) when:

  • Start (I0.0) is pressed

  • AND Stop (I0.1) is NOT pressed

  • AND Motor output (Q0.0) is held ON through latching

• The latching branch uses the motor’s output (Q0.0) to keep the rung true even after releasing the Start button.

• Pressing the Stop button breaks the rung logic, de-energizing the motor.

 

AND & OR Gate Opertion in Ladder language

AND & OR Gate Operation Using Ladder Logic

🎯 Objective:

Control two lamps using four switches through:

• AND Gate logic (series connection)
• OR Gate logic (parallel connection)

📘 Application Description

We have four input switches and two output lamps. Two control scenarios are implemented:

✅ Task 1 – AND Gate Logic (Series Connection)

• Inputs: SW1 (I0.0), SW2 (I0.1)
• Output: Lamp 1 (Q0.0)
• Logic: Lamp 1 turns ON only if both SW1 and SW2 are turned ON.
• Equivalent to: Q0.0 = I0.0 AND I0.1

✅ Task 2 – OR Gate Logic (Parallel Connection)

• Inputs: SW3 (I0.2), SW4 (I0.3)
• Output: Lamp 2 (Q0.1)
• Logic: Lamp 2 turns ON if either SW3 or SW4 is ON.
• Equivalent to: Q0.1 = I0.2 OR I0.3

🧠 Input/Output Assignment

Device	Address
SW1	I0.0
SW2	I0.1
SW3	I0.2
SW4	I0.3
Lamp 1	Q0.0
Lamp 2	Q0.1

 

Network 1 :-The first rung connects SW1 and SW2 in series—mimicking an AND gate.

Network 2 :- The second rung connects SW3 and SW4 in parallel—mimicking an OR gate.