Embedding an FMU into a standalone app

This project demonstrates how to simulate an FMI 2.0 source code FMU as a standalone app. It consists of a simple C program that creates an instance of the Heater model. Its simulation loop turns the power for the heatingResistor on and off by setting the input variable u to keep the temperature T of the heatCapacitor at 40 °C.

For each time step the current simulation time, u and T are displayed on the command line:

time, u, T
0.00, 0, -7.15
0.10, 0, 20.72
0.20, 0, 21.43
0.30, 0, 22.14
...
3.40, 0, 39.82
3.50, 1, 40.28
3.60, 1, 40.73
3.70, 1, 40.26
3.80, 0, 39.79
3.90, 0, 39.32
4.00, 0, 39.78
4.10, 1, 40.23
4.20, 1, 40.68
4.30, 1, 40.21
4.40, 0, 39.74
...

Project Structure

• Heater.mo - Modelica model of the Heater
• model - extracted FMU (exported with Dymola 2021)
• include/fmi2*.h - FMI headers
• include/model.h - model specific constants
• src/simulator.c - source code of the standalone app
• import_fmu.py - Python script to reimport the FMU
• CMakeLists.txt - the CMake project for the console app
• Heater - Qt project for the graphical app

Building the Standalone App

Prerequisites

• a clone or extracted download of this repository
• CMake to generate the Visual Studio solution on Windows or Makefiles on Linux
• a supported toolchain to build the App (run cmake --help to get a list of all available generators)
• Dymola to export the FMU (optional)
• Python and FMPy to reimport the FMU (optional)

Building on Windows with Visual Studio

• run cmake -G"Visual Studio 15 2017 Win64" -Bbuild . to generate a Visual Studio 2017 solution

• open build/simulator.sln in Visual Studio 2017

• In the Project Explorer right-click on the simulator project and select Debug > Start new instance to build and run the app

Building on Linux with GCC

• run cmake -Bbuild . to generate the Unix Makefiles

• run cmake --build build to build the app

• run the app with ./build/simulator

Exporting the FMU

• in Dymola 2021 click File > Open > Load... and select Heater.mo

• on the Simulation tab open the Translate menu and select FMU

• in the Export FMU select the following options and click OK

Reimporting the FMU

To reimport the FMU run the following command

python import_fmu.py Heater.fmu

This will extract Heater.fmu to the model directory and create a include/model.h with the model specific constant. The script requires Python and FMPy.

Embedding an FMU into a graphical Qt app

The "Heater" Qt app demonstrates how to embed an FMU into an application with a graphical user interface (GUI). It has a spin box to set the TAmb parameter and a push button to control the input u that closes the idealSwitch. The temperature T is displayed as an LCD number.

Building the Qt App

• install Qt 6
• open QtCreator, import Heater/CMakeLists.txt and conifigure the project
• build the project and copy model/binaries/win64/Heater.dll next to Heater.exe
• run the project

Deploying the Qt App

To deploy the Qt app use windeployqt.exe.