LDmicro Web Simulator

A web-based PLC ladder logic simulator that interprets LDmicro text exports and runs them on a virtual training board with interactive inputs and outputs.

✨ Features

• Text Export Focus: Import ladder logic from LDmicro text ladder diagram export
• Interactive Virtual Board: Simulates a physical PLC training board with:
  • 🔘 Sensors (light, proximity, motion, trigger, metal detectors)
  • 🔲 Toggle switches (S1, S2, S3)
  • 🟢 Push buttons (BTN1, BTN2, BTN3)
  • 🌀 Fans (FAN1, FAN2, FAN3)
  • 💡 Indicator lights (H1-green, H2-yellow, H3-red)
  • 🚨 Panic strobe and buzzer
• Real-time Simulation: Execute PLC cycles with adjustable speed
• Step Debugging: Single-step through the ladder logic
• Modern UI: Industrial control panel aesthetic with responsive design

🚀 Quick Start

Using Docker (Recommended)

# Clone the repository
git clone https://github.com/soggy8/LDmicroWebSim.git
cd LDmicroWebSim

# Start with Docker Compose
docker-compose up -d

# Open in browser
open http://localhost:8000

Manual Installation

# Clone the repository
git clone https://github.com/soggy8/LDmicroWebSim.git
cd LDmicroWebSim

# Create virtual environment
python3 -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install dependencies
pip install -r requirements.txt

# Run the server
python server.py

Then open http://localhost:8000 in your browser.

📖 Usage

Step 1: Export from LDmicro

In LDmicro, export your ladder diagram as text:

• Text Format: File → Export As → Text

Step 2: Load into Simulator

Either:

• Paste the exported code directly into the editor
• Click "Upload" to load a file
• Click "Load Example" for a demo

Step 3: Compile & Run

1. Click Compile to parse the ladder logic
2. Click Run to start the simulation
3. Interact with the virtual board inputs
4. Watch the outputs respond in real-time!

📋 Supported LDmicro Elements

Element	Symbol	Description
Normally Open Contact	] [	True when input is ON
Normally Closed Contact	]/[	True when input is OFF
Output Coil	( )	Energize output
Set Coil	(S)	Latch ON
Reset Coil	(R)	Latch OFF
Timer On-Delay	[TON]	Delay before turning ON
Timer Off-Delay	[TOF]	Delay before turning OFF
Counter Up	[CTU]	Count up
Counter Down	[CTD]	Count down

🎛️ Virtual Board I/O Names

Use these names in your LDmicro program to map to the virtual board:

Inputs

Name	Type	Description
FOTO / XFOTO	Sensor	Light sensor
SEN / XSEN	Sensor	Proximity sensor
MOV / XMOV	Sensor	Movement sensor
TRIG / XTRIG	Sensor	Trigger/door sensor
PO1 / XPO1	Sensor	Metal detector 1
PO2 / XPO2	Sensor	Metal detector 2
S1 / XS1	Switch	Toggle switch 1
S2 / XS2	Switch	Toggle switch 2
S3 / XS3	Switch	Toggle switch 3
BTN1 / XBTN1	Button	Push button 1 (green)
BTN2 / XBTN2	Button	Push button 2 (yellow)
BTN3 / XBTN3	Button	Push button 3 (red)

Outputs

Name	Type	Description
FAN1 / YFAN1	Fan	Fan 1
FAN2 / YFAN2	Fan	Fan 2
FAN3 / YFAN3	Fan	Fan 3
H1 / YH1	Light	Green indicator
H2 / YH2	Light	Yellow indicator
H3 / YH3	Light	Red indicator
PANIC / YPANIC	Strobe	Panic strobe light
BELL / YBELL	Buzzer	Emergency bell
LOCK / YLOCK	Lock	Door lock / solenoid (digital output)
K1 / YK1	Contactor	Power contactor 1
K2 / YK2	Contactor	Power contactor 2
K3 / YK3	Contactor	Power contactor 3

Note: LDmicro uses X prefix for inputs and Y prefix for outputs. The simulator automatically handles both conventions.

📁 Project Structure

LDmicroWebSim/
├── server.py              # FastAPI backend server
├── interpreter/
│   ├── __init__.py
│   ├── ladder_parser.py   # Ladder text parser
│   └── unified_transpiler.py  # Ladder text to JS transpiler
├── static/
│   ├── index.html         # Main UI
│   ├── styles.css         # Industrial theme CSS
│   └── simulator.js       # Browser simulation engine
├── examples/
│   └── simple_ladder.txt  # Example ladder text export
├── Dockerfile
├── docker-compose.yml
└── requirements.txt

🐳 Docker Configuration

The included Docker setup provides:

• Python 3.11 slim image
• Automatic dependency installation
• Hot-reload for development
• Port 8000 exposed

# docker-compose.yml
services:
  ldmicro-sim:
    build: .
    ports:
      - "8000:8000"
    volumes:
      - .:/app  # For development hot-reload

🔧 Development

# Run in development mode with auto-reload
uvicorn server:app --reload --host 0.0.0.0 --port 8000

📝 Example Ladder Diagram

LDmicro export text
for 'Microchip PIC16F877 40-PDIP', 8.000000 MHz crystal, 0.5 ms cycle time

LADDER DIAGRAM:

   ||                                                   ||
   ||       XS1              XS2              YH1       ||
 1 ||-------] [--------------]/[--------------( )-------||
   ||                                                   ||
   ||       XS2              XS3              YH2       ||
 2 ||-------] [--------------]/[--------------( )-------||
   ||                                                   ||
   ||       XS3              XS1              YH3       ||
 3 ||-------] [--------------]/[--------------( )-------||
   ||                                                   ||
   ||------[END]----------------------------------------||

I/O ASSIGNMENT:

  Name    | Type           | Pin
 ---------+----------------+------
  XS1     | Digital input  | 2
  XS2     | Digital input  | 3
  XS3     | Digital input  | 4
  YH1     | Digital output | 21
  YH2     | Digital output | 22
  YH3     | Digital output | 23

This creates a "rotating light" pattern:

• S1 ON + S2 OFF → H1 (green) ON
• S2 ON + S3 OFF → H2 (yellow) ON
• S3 ON + S1 OFF → H3 (red) ON

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• LDmicro - The original ladder logic compiler
• Inspired by physical PLC training boards used in education

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Made with ❤️ for PLC education and simulation