Boolean Logic to PLC Programming

This article teaches how to convert Boolean logic to PLC programming ladder logic with the video tutorial.

Note: The logic diagram example shown here is for educational use only for engineering students to understand PLC principles.

Boolean Logic to PLC

Problem Statement

Design a PLC ladder logic for the following Boolean Expression.

We are using toggle Inputs to control the output.

Convert the boolean logic to PLC logic.

Y = A’B

Video

The below video explains the boolean logic conversion with detailed steps.

Inputs

The required inputs mentioned below.

A: I0.0

B: I0.1

Outputs

The required outputs mentioned below.

Y: Q0.0

PLC Programming

The equivalent PLC programming is shown below.

Boolean Logic to PLC Programming

Program Description

  • We used Schneider PLC programming software.
  • In the above program, we have used Normally Closed Contact for Input A and  Normally Open Contact for Input B.
  • Normally Closed Contact is used for Input A, thus implementing NOT Logic Gate.
  • For the output Y (Q0.0) to be ON, Input A should be OFF and Input B should be ON.
  • Input A will only pass the signal when it is in a false state.
  • Turning ON Input A will turn OFF Y(Q0.0) because Normally Closed Contact in the true state does not allow the signal to pass through it.

Result

When Input A is OFF and Input B is ON

PLC Boolean Logic

The signal will pass through Input A as Normally Closed Contact will pass the signal through it when in a false state. Also, Input B will pass the signal when in the true state because it is in Normally Open Contact, and Y(Q0.0) will turn ON.

When the input A is turned ON, as it is Normally Closed Contact, it will not allow the signal to pass. The state of Input B will not matter as the signal will not reach there when the input A is ON.

As a result, the output Y (Q0.0) will not turn ON. So, for the output Y (Q0.0) to be ON. The Input A should be OFF and the Input B should be ON.

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