Lesson#8 Simple Motor Reverse Forward RUN Logic

Overview

Here is a simple motor Forward/Reverse RUN logic in Ladder Logic, typically used in PLC programming for a 3-phase motor with two contactors (one for Forward, one for Reverse), and ensuring interlocking to prevent both directions from being ON at the same time.


🧠 Logic Overview

  • Inputs:

    • I0.0 → Forward Push Button (NO)

    • I0.1 → Reverse Push Button (NO)

    • I0.2 → Stop Push Button (NC)

  • Outputs:

    • Q0.0 → Forward Contactor Coil

    • Q0.1 → Reverse Contactor Coil

  • Interlocks to prevent both directions running together.

  • Sealing (latching) for continuous running until stop is pressed.


🔧 Ladder Logic Explanation

ladder
| I0.2 I0.0 Q0.0 Q0.1 Start Forward |----+----| |----+----|/|-------------() Q0.0 | | | | | +----| |------------------------+ | I0.2 I0.1 Q0.1 Q0.0 Start Reverse |----+----| |----+----|/|-------------() Q0.1 | | | | | +----| |------------------------+

📋 Description

1. Forward Run Logic (Q0.0)

  • Starts when:

    • Stop button is not pressed (I0.2 is TRUE).

    • Forward button is pressed (I0.0 is TRUE).

    • Reverse output is OFF (Q0.1 is FALSE).

  • Self-holds (latched) using Q0.0.

  • Breaks when Stop button is pressed or reverse is triggered.

2. Reverse Run Logic (Q0.1)

  • Starts when:

    • Stop button is not pressed.

    • Reverse button is pressed.

    • Forward output is OFF.

  • Self-holds using Q0.1.