OpenModelica-PyQt-Desktop-App

A Python/PyQt6 desktop application that lets you launch and configure any OpenModelica-compiled simulation executable through a clean graphical user interface — no command line required.

---

Purpose

OpenModelica compiles Modelica models into standalone Windows executables. These executables accept simulation flags (-startTime, -stopTime, etc.) as command-line arguments, which is inconvenient for users who are not familiar with the command line.

This application wraps that workflow in a simple GUI:

1. Browse to the compiled .exe
2. Enter a start time and stop time
3. Click Run Simulation

The app validates all inputs before running, streams the simulation output into the window, and reports success or failure clearly.

---

Project Structure

OpenModelica-PyQt-Desktop-App/
├── app/
│   ├── __init__.py          # Makes app/ a Python package
│   └── main_window.py       # MainWindow class — all GUI and simulation logic
├── simulation/
│   ├── TwoConnectedTanks.exe
│   ├── TwoConnectedTanks_init.xml
│   └── *.dll                # OpenModelica runtime DLLs (self-contained)
├── main.py                  # Entry point — creates QApplication and shows MainWindow
├── requirements.txt         # Python dependencies
└── README.md

---

Requirements

Requirement	Version
Python	3.6 or higher
PyQt6	6.0 or higher
OS	Windows (64-bit)

Note: OpenModelica does not need to be installed on the target machine. All required DLLs are bundled in the simulation/ folder.

---

Installation

# Clone or download the repository
git clone https://github.com/ekagrazi/OpenModelica-PyQt-Desktop-App.git
cd OpenModelica-PyQt-Desktop-App

# Install the Python dependency
pip install -r requirements.txt

---

Usage

Launch the application

python main.py

Step-by-step

1. Browse — Click the Browse button next to the first field and select the OpenModelica-compiled .exe (e.g. simulation/TwoConnectedTanks.exe).

2. Start Time — Enter an integer ≥ 0 (e.g. 0).

3. Stop Time — Enter an integer that is greater than Start Time and strictly less than 5 (e.g. 4).

   Constraint: 0 ≤ startTime < stopTime < 5

4. Run Simulation — Click the ▶ Run Simulation button. The output box displays the command that was run, the simulation output, and a success or error message.

Example — valid run

Field	Value
Executable	simulation/TwoConnectedTanks.exe
Start Time	0
Stop Time	4

The app constructs and executes:

TwoConnectedTanks.exe -startTime=0 -stopTime=4

Validation rules (shown as error dialogs, app never crashes)

Bad input	Error shown
No executable selected	"Executable path is empty."
Non-integer start/stop	"Start time '...' is not a valid integer."
start ≥ stop	"Times must satisfy 0 ≤ start < stop < 5"
stop ≥ 5	"Times must satisfy 0 ≤ start < stop < 5"

---

Methodology

The application follows a clean MVC-like separation:

• main.py — bootstrap only (creates QApplication, shows window).
• app/main_window.py — the MainWindow class encapsulates all GUI construction (_build_ui), input validation (_validate_inputs), file browsing (_browse_executable), and simulation execution (_run_simulation).

Simulation is launched via Python's subprocess.run with:

• capture_output=True — both stdout and stderr are captured.
• cwd set to the folder containing the exe — so the exe can find its companion .xml data files next to it.
• timeout=60 — the run is aborted and an error dialog is shown if the simulation takes longer than 60 seconds.

---

Technologies

Technology	Role
Python 3	Application language
PyQt6	Cross-platform GUI framework
OpenModelica	Modelica model compiler / simulation engine
subprocess	Launching the simulation executable
Windows 64-bit	Target operating system

---