QModbusUniversal - Universal Modbus Testing Tool

A powerful Qt-based Modbus testing application with visual modeling capabilities for protocol development, testing, and monitoring.

Features

Core Functionality

• Multi-Protocol Support: Both Modbus TCP and Modbus RTU
• Visual Register Modeling: Create, edit, and manage Modbus registers with an intuitive UI
• Real-time Monitoring: Continuous polling of register values
• Trigger System: Event-based actions when register conditions are met
• Project Management: Save and load complete protocol configurations

Register Management

• Support for all Modbus register types:

  • Coils (FC01/FC05/FC15)
  • Discrete Inputs (FC02)
  • Holding Registers (FC03/FC06/FC16)
  • Input Registers (FC04)

• Multiple data types:

  • Bool (1 bit)
  • UInt16 / Int16 (16-bit integers)
  • UInt32 / Int32 (32-bit integers)
  • Float32 (IEEE 754 floating point)

• Read-only and read-write register support

• Individual register polling intervals

• Batch read operations

Connection Management

• TCP Configuration:

  • IP address and port
  • Configurable timeout and retries

• RTU Configuration:

  • Serial port selection
  • Baud rate (9600-115200)
  • Data bits, stop bits, parity

• Connection status monitoring

• Automatic reconnection handling

Trigger System

• Condition-based event monitoring
• Supported conditions: ==, !=, >, <, >=, <=
• Custom action descriptions
• Real-time trigger evaluation during polling

Building the Application

Prerequisites

Ubuntu/Debian

sudo apt-get update
sudo apt-get install qt5-default qtbase5-dev qttools5-dev-tools
sudo apt-get install libqt5serialbus5-dev libqt5serialport5-dev

Fedora/RHEL

sudo dnf install qt5-qtbase-devel qt5-qttools-devel
sudo dnf install qt5-qtserialbus-devel qt5-qtserialport-devel

macOS

brew install qt@5
export PATH="/usr/local/opt/qt@5/bin:$PATH"

Windows

Download and install Qt from https://www.qt.io/download Make sure to include:

• Qt 5.12+ (or Qt 6.x)
• Qt SerialBus module
• Qt SerialPort module

Build with qmake

cd QModbusUniversal-master
qmake QModbusUniversal.pro
make

Build with CMake (Alternative)

mkdir build
cd build
cmake ..
make

Running the Application

Linux/macOS

./QModbusUniversal

Windows

QModbusUniversal.exe

Usage Guide

Creating a New Project

1. File → New Project to start fresh
2. Configure connection settings:
   • Choose TCP or RTU
   • Enter connection parameters
   • Set slave ID (default: 1)

Adding Registers

1. Click Add Register button
2. Configure register properties:
   • Name (identifier)
   • Register Type (Coil, Holding Register, etc.)
   • Address (0-65535)
   • Data Type (Bool, UInt16, Int32, etc.)
   • Description (optional)
   • Read Only checkbox
   • Poll Interval (0 = manual only)

Reading/Writing Data

Manual Operations

• Read All: Read all configured registers once
• Read Selected: Read currently selected register
• Write Selected: Write to selected register (if not read-only)
• Double-click value cell to quickly write new value

Continuous Polling

1. Set poll interval (milliseconds)
2. Click Start in Polling section
3. Only registers with poll interval > 0 will be polled
4. Click Stop to halt polling

Setting Up Triggers

1. Switch to Triggers tab
2. Click Add Trigger
3. Configure:
   • Select register to monitor
   • Choose condition (==, !=, >, <, >=, <=)
   • Enter threshold value
   • Describe action (logged when triggered)
4. Triggers are evaluated during polling

Saving Projects

• File → Save Project (Ctrl+S)
• File → Save Project As... (Ctrl+Shift+S)
• Projects saved as .mbproj JSON files
• Contains all registers, triggers, and settings

Project Structure

QModbusUniversal/
├── main.cpp                 # Application entry point
├── mainwindow.h/.cpp/.ui    # Main window and UI logic
├── modbusregister.h/.cpp    # Register data model
├── modbusproject.h/.cpp     # Project container with serialization
├── registerdialog.h/.cpp/.ui # Register configuration dialog
├── triggerdialog.h/.cpp/.ui  # Trigger configuration dialog
├── QModbusUniversal.pro     # Qt project file
├── CMakeLists.txt           # CMake build configuration
└── README.md                # This file

Data Type Conversions

Register Layout

• Bool: 1 register (0 or 1)
• UInt16/Int16: 1 register
• UInt32/Int32/Float32: 2 registers (big-endian)

Byte Order

All multi-register values use big-endian byte order:

• First register contains most significant 16 bits
• Second register contains least significant 16 bits

Testing and Development

Testing Modbus Penetrations

This tool is particularly useful for:

• Protocol fuzzing and edge case testing
• Penetration testing of Modbus implementations
• Validating device behavior under various conditions
• Simulating client interactions

Development Workflow

1. Create protocol model (registers)
2. Connect to device/simulator
3. Test read/write operations
4. Set up triggers for monitoring
5. Enable polling for continuous monitoring
6. Save project for later use

Troubleshooting

Connection Issues

• TCP: Verify host IP and port are correct
• RTU: Check serial port permissions (sudo chmod 666 /dev/ttyUSB0)
• Verify slave ID matches device configuration
• Increase timeout if device is slow to respond

Build Issues

• Ensure Qt SerialBus module is installed
• Check Qt version (minimum Qt 5.12)
• On Linux, you may need to install libqt5serialbus5-dev package

Runtime Issues

• Check log tab for error messages
• Verify register addresses match device configuration
• Ensure data types match register contents
• For RTU, verify serial parameters match device

License

This project is provided as-is for educational and testing purposes.

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues for bugs and feature requests.