Logic Gates using PLC Ladder | Important for Basic Programming

Equivalent Logic Gates in PLC ladder logic with boolean logic and circuit. The understanding of these functions is important for the basic level of PLC programming.

This is the list of all logic gates:

  • AND Gate
  • OR Gate
  • NOT Gate
  • NAND Gate
  • NOR Gate
  • EX-OR Gate
  • EX-NOR Gate

Implementation of Logic Gates using PLC Program

1. AND Gate

AND logic gate is the basic multiplication logic gate. The output will turn ON only if all the inputs will be ON.

PLC Logic Gates
AND Gate: Y = A * B

The below figure shows the PLC ladder logic of AND gate, which shows the output coil turns “ON” when both the input will be ON.

PLC Logic Gates
PLC Ladder Logic of AND Gate

2. OR Gate

OR logic gate is the basic addition logic gate. The output will turn ON if any of the inputs will be ON.

PLC Logic Gates
OR Gate: Y = A + B

The below figure shows the PLC ladder logic of the OR gate, which shows the output coil turns “ON” when any one of the inputs will be ON.

PLC Logic Gates
PLC Ladder Logic of OR Gate

3. NOT Gate

NOT logic gate is the inverse logic gate. When the input is ON, the output will be OFF and when the input is OFF, the output will be ON.

PLC Logic Gates
NOT Gate: Y = (!A)

The below figure shows the PLC ladder logic conversion of NOT gate, which shows the output works exactly opposite of the input.

PLC Logic Gates
PLC Ladder Logic of NOT Gate

4. NAND Gate

NAND logic gate is the combination of AND and NOT logic gates, Output will only be OFF when all the inputs will be ON.

PLC Logic Gates
NAND Gate: Y = (!(A*B)) OR ((!A)+(!B))

The below figure shows the plc ladder logic conversion of the NAND gate, which shows that when all the inputs will ON then the output will be OFF.

PLC Logic Gates
PLC Ladder Logic of NAND Gate

5. NOR Gate

NOR logic gate is the combination of OR and NOT logic gates, Output will only be ON when all the inputs will be OFF.

PLC Logic Gates
NOR Gate: Y = (!(A + B)) OR ((!A)*(!B))

The below figure shows the PLC ladder logic of the NOR logic gate, which shows that Output will only turn ON when all the inputs will be OFF.

PLC Logic Gates
PLC Ladder Logic of NOR Gate

6. EX-OR Gate

EX-OR logic gate is the combination of AND, NOT and OR gate.

PLC Logic Gates
EX-OR Gate: Y = (A*(!B)) + ((!A)*B)
PLC Logic Gates
EX-OR Gate combination with NOT, AND, OR Gates

The below figure shows the ladder logic conversion of the EX-OR logic gate.

PLC Logic Gates
PLC Ladder Logic of EX-OR Gate

7. EX-NOR Gate

EX-NOR logic gate is the combination of AND, OR and NOT gate.

PLC Logic Gates
EX-NOR Gate: Y = (A*B) + ((!A)*(!B))
PLC Logic Gates
EX-NOR Gate combination of AND, NOT, OR Gates

The below figure shows the ladder logic conversion of the EX-NOR logic gate.

PLC Logic Gates
PLC Ladder Logic of EX-NOR Gate

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