Can I Use CLAUDE AI to Program a PLC Successfully?

START-STOP CIRCUIT LADDER LOGIC
================================

Rung 1:
| |
| I:0/0 I:0/1 O:0/0 |
|—–| |———-| |———————( )————-|
| STOP | MOTOR |
| | |
| | O:0/0 |
| +—–| | |
| SEAL-IN |
| |

Better explanation of the layout:

• Left vertical line = Power rail
• Right vertical line = Return rail
• I:0/0 (Stop) = Normally Closed contact in series
• I:0/1 (Start) and O:0/0 (Seal-in) = Two parallel branches (the “+” shows the branch point)
• O:0/0 = Motor output coil at the end

Flow:

1. Power flows through the NC STOP contact
2. Then splits into two parallel paths:
   • Through the NO START button, OR
   • Through the NO SEAL-IN contact
3. If either path is closed, power reaches the MOTOR coil

Would you like me to create this as a visual diagram instead, or is there a specific format you’d prefer for the ladder logic?

Try creating the ladder logic as a visual diagram.

I’ll create a visual ladder logic diagram for you!

Perfect! Now you can see the ladder logic properly visualized. Here’s how to read it:

Circuit Flow:

1. Left power rail → STOP button (NC) → Junction point
2. From the junction, power can flow through two parallel paths:
   • Upper path: Through START button (NO)
   • Lower path: Through SEAL-IN contact (NO)
3. Both paths rejoin and continue to the MOTOR output coil → Right power rail

Operation:

• Press START: Closes I:0/1, energizes O:0/0 (motor runs), and the O:0/0 seal-in contact closes to maintain the circuit
• Release START: Motor keeps running because seal-in contact is now closed
• Press STOP: Opens I:0/0, breaking the circuit and stopping the motor

This is the standard self-holding (latching) circuit used in industrial controls. Is this clearer now?

There we go! Now the ladder logic diagram has proper symbols:

Key Features:

• STOP (I:1/0): Normally Closed contact shown with diagonal slash through it
• START (I:1/1): Normally Open contact with visible gap in the middle
• MOTOR Seal-in (O:2/0): Another Normally Open contact in parallel with START
• MOTOR (O:2/0): Output coil shown with the circle and ( ) symbol
• Parallel branches: The START and SEAL-IN contacts are in parallel, so either one can energize the motor

The legend at the bottom shows what each symbol means. Does this look correct now?

Yes, this looks correct now, but the stop pushbutton is wired normally closed, so the ladder symbol should be normally open to work.

You’re absolutely right! That’s a critical point in PLC programming that I got wrong.

When the physical STOP pushbutton is wired normally closed, the ladder logic symbol should be normally open because:

• Physical NC button not pressed = contacts closed = input is ON (1) = NO contact in ladder is CLOSED
• Physical NC button pressed = contacts open = input is OFF (0) = NO contact in ladder OPENS

Let me fix the diagram:

Perfect! Now it’s correct. Thank you for catching that important detail!

The key principle:

• Physical STOP button: Normally Closed (NC) – contacts are closed at rest
• Ladder logic symbol: Normally Open (NO) – because when input I:1/0 is energized (button not pressed), the contact closes

How it works now:

1. Normal operation: Physical NC stop button is closed → Input I:1/0 is ON → NO contact in ladder is CLOSED → allows power to flow
2. When STOP pressed: Physical NC stop button opens → Input I:1/0 is OFF → NO contact in ladder OPENS → breaks the circuit and stops motor

This is a fundamental concept in PLC programming – you program the opposite of the physical device wiring because you’re reading the input state, not the physical contact state.

Now the circuit will work correctly! Thanks for keeping me accurate.

Correcting AI for the Do-More Designer Programming Software Simulator

Thank you. I am using the Do-More Designer programming software with the simulator. Can you change the input and output addresses?

Absolutely! Do-More Designer uses different addressing conventions. Let me update it to use the proper Do-More addresses:

Perfect! I’ve updated the addresses to Do-More Designer format:

Input Addresses:

• X0 = STOP pushbutton (physical NC button)
• X1 = START pushbutton (physical NO button)

Output Address:

• Y0 = MOTOR output (both the output coil and the seal-in contact)

These are the standard discrete I/O addresses for Do-More Designer. When you program this in the simulator, you’ll be able to:

• Toggle X0 and X1 to simulate pressing the buttons
• Watch Y0 energize when you press START and latch on
• Watch Y0 de-energize when you press STOP

The circuit should work perfectly in the Do-More Designer simulator now!

The ladder diagram is not showing correctly.

Let me redraw the entire diagram cleanly to make sure everything displays correctly:

There you go! I’ve redrawn the entire diagram cleanly with the correct Do-More Designer addresses:

Addresses:

• X0 = STOP pushbutton input (NO symbol in ladder because physical button is NC)
• X1 = START pushbutton input (NO symbol)
• Y0 = MOTOR output (used for both the output coil and the seal-in contact)

Is the diagram displaying correctly now?

Yes, thank you. I will now try this in the PLC programming software