Modbus RTU Scanner

A Windows Forms application for scanning and detecting Modbus RTU devices on serial ports with various communication parameters.

Overview

Modbus RTU Scanner is a diagnostic tool that helps you identify the correct communication settings for Modbus RTU devices. It systematically tests different combinations of serial port parameters (baud rate, data bits, parity, stop bits, and handshake) to find working configurations. The scanner automatically stops when a valid configuration is found.

Features

• Serial Port Detection: Automatically detects and lists available COM ports (sorted numerically)
• Configurable Parameters: Test multiple combinations of:
  • Baud Rates: 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 56000, 57600, 115200, 128000, 230400, 256000, 460800, 921600
  • Data Bits: 5, 6, 7, 8
  • Parity: None, Odd, Even, Mark, Space
  • Stop Bits: One, OnePointFive, Two
  • Handshake: None, XOnXOff, RequestToSend, RequestToSendXOnXOff
  • Modbus Functions:
    • 01 - Read Coils
    • 02 - Read Discrete Inputs
    • 03 - Read Holding Registers
    • 04 - Read Input Registers
    • 05 - Write Single Coil
    • 06 - Write Single Register
    • 15 - Write Multiple Coils
    • 16 - Write Multiple Registers
• Device ID Selection: Scan for specific Modbus slave IDs (0-247)
• Configurable Timeout: Adjustable timeout per configuration test (default: 1000ms)
• Progress Tracking: Visual progress bar showing scan progress with real-time ETA
• Color-Coded Logging:
  • Green background for successful device detection
  • Red background for errors and failures
  • Real-time logging with file logging support
• Smart Scanning: Automatically stops when a valid configuration is found
• Cancellable Scans: Stop ongoing scans at any time
• Time Estimation: Provides estimated scan duration before starting
• Default Settings: Pre-configured with common communication parameters

Requirements

• .NET 10
• Windows operating system
• Serial port access permissions
• NModbus library
• NLog library

Usage

1. Select Serial Port: Choose the COM port where your Modbus device is connected
2. Select Device ID: Choose the Modbus slave ID to scan (default: 1)
3. Configure Parameters: Check the communication parameters you want to test:
   • Default common settings are pre-selected
   • Select multiple options to test more combinations
   • Choose which Modbus functions to test (default: 03 - Read Holding Registers)
4. Start Scan: Click "Start Scan" to begin
   • The application will show estimated scan time
   • Confirm to proceed
5. Monitor Progress: Watch the progress bar and log output
6. Review Results: Successful configurations are marked with ✓ SUCCESS

Technical Details

• Built with Windows Forms (.NET 10)
• Uses NModbus library for Modbus RTU communication with CRC frame checking enabled
• Implements NLog for rotating file logs (stored in /logs directory)
• Asynchronous scanning with cancellation token support
• Configurable timeout per configuration test (default: 1000ms)
• Tests Modbus function codes: 01, 02, 03, 04, 05, 06, 15, 16
• Attempts to read/write from address 0 with 1 register to verify device communication
• Smart scanning: stops immediately when a valid configuration is found
• Color-coded logging for easy identification of results
• Detailed error reporting including Modbus slave exception codes

Log Files

Logs are automatically saved to:

• Location: {ApplicationDirectory}/logs/logfile.log
• Rotation: Daily
• Retention: 7 days

Building

This project requires:

• Visual Studio 2022 or later
• .NET 10 SDK

License

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Contributing

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