By the end of this lesson, viewers will learn how to create a reusable motor control block using ladder logic in Simatic Manager (S7-300/400) with Start/Stop control and interlocks.

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🧠 Step-by-Step Tutorial Script

🟢 1. Introduction (0:00–0:30)

• Briefly introduce what a motor control block is.

• Explain the benefits: reusability, structured programming, and safety interlocks.

🔧 2. Open Simatic Manager Project (0:30–1:00)

• Open your existing Step 7 project.

• Navigate to “Blocks” under your PLC program.

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🧱 3. Create a New Function Block (FB) (1:00–1:30)

• Right-click > Insert New Object > Function Block (FB).

• Name it FB_MotorControl.

• Select "LAD" (Ladder) as the language.

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🛠️ 4. Define Inputs and Outputs (1:30–2:00)

In the Interface of the FB:

Inputs:

• Start: BOOL

• Stop: BOOL

• Fault: BOOL (optional interlock)

• Reset: BOOL (optional)

Outputs:

• MotorON: BOOL

Static (Memory):

• MemoryBit: BOOL (used to latch ON signal)

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🔌 5. Ladder Logic Implementation (2:00–3:30)

Draw the following logic in the ladder editor:

Network 1: Motor Start/Stop Latching

• A basic SR (Set-Reset) latch logic:

  • Start ---| |-----+

  • | |

  • M bit ---| |--+ |

  • Fault ---|/|--| |

  • Stop ----|/|--|--( ) MotorON
    |
    +--( ) M bit

Explanation:

• When Start is pressed and no Fault, motor latches ON.

• When Stop is pressed or Fault occurs, motor stops.

• M bit helps to hold the ON state.

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♻️ 6. Reuse Motor Control Block in OB1 (3:30–4:30)

• Go to OB1 (main program).

• Call the FB instance:

  • Create instance DB (e.g., DB1 for Motor1).

  • Assign inputs:

    • Start := I0.0

    • Stop := I0.1

    • Fault := I0.2

  • Assign output:

    • MotorON → Q0.0

ladder
CopyEdit
CALL FB1, DB1
Start := I0.0
Stop := I0.1
Fault := I0.2
MotorON := Q0.0

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⚡ 7. Test in PLC Simulator or Actual PLC (4:30–5:30)

• Download the program to the simulator or real PLC.

• Monitor the logic by toggling inputs.

• Show MotorON output reacting correctly.

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📦 8. Tips for Improvement (5:30–6:00)

• Add thermal overload, feedback from contactor.

• Add multiple motor blocks for different machines using the same FB.

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🎯 Conclusion (6:00–6:30)

• Recap: We created a modular, reusable motor control block in LAD.

• Encourage users to modify it for different motor logic or safety conditions.

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📝 Summary Notes for Your Viewers

• Use FB + instance DB for each motor.

• Reuse logic with different input/output parameters.

• Helps in large automation systems with 10+ motors.

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