About the FMI Code Generator

What is this FMI/FMU stuff?

FMU stands for Functional Mockup Unit and FMI for Functional Mockup Interface. The latter is an industry standard for simulation model runtime coupling, and basically defines an API and a meta data description file and directory structure: see FMI-Standard webpage for details.

The Motivation

When you want an efficient/fast FMU slave, there's probably no way around a native C/C++ implementation. However, implementing the C interface functions, the data handling, input/output variable handling and advanced features like saving and restoring the FMU state is not so simple and straight-forward.

However, the process of setting up the FMU (core files, modelDescription.xml, directory structure) is pretty similar for most projects and can be automated with a configurable code generator - hence this project.

What FMI Code Generator is not

This is not a Software Development Library/Toolkit for accessing/supporting the FMI interface. Look at the FMU SDK or other projects on fmi-tools if you need something like that.

Actually, the code generated by FMI Code Generator hides most of the messy FMI C function interface (including most of the memory management related to instantiating/deleting slave instances, and the state storage stuff) from the typical (engineering) user. Also, the generated code is pretty small, easy to read and comprehend and works cross-platform without any library setup issues.

The (anticipated) use of the FMI Code Generator

See description of Test scenario: Stateless P-controller for a step-by-step tutorial.

Step 1: Create a fully working FMU source code template

Creating the barebone of an FMU should be as simple as that:

1. clone this repository
2. run the Python program scripts/main.py or scripts/FMIGeneratorWizard.py
3. give the relevant information (model name, list of input and output vars, parameters, integration states etc.)

Once the generator has finished, you have a directory structure with fully working FMU source code (including build system files) with matching modelDescription.xml that you can build cross-platform with the provided CMake-based build system.

Step 2: Develop FMU-specific functionality

The generated directory structure contains build system files for CMake and Qt-qmake. With CMake, you can easily generate makefiles for various compilers and development environments. With the pro-files you can directly start developing with Qt Creator (even though the FMU code itself is plain C/C++ code without Qt dependencies).

You can now start to implement your FMU-specific logic (physics, mathematical functions) by opening the <FmuModelName>.cpp file within the <FmuModelName>/src/ subdirectory. The places where your own code is usually placed are marked with TODO comments.

Test-compile the source code using the provided build system files.

Step 3: Generate the FMU and deploy

The template directory structure contains a deployment script/batch file (either <FmuModelName>/build/deploy.sh or <FmuModelName>/build/deploy.bat).

You may want to adjust the deploy.sh script to add copying of own resource files, if needed.

Deployment works as follows (for Linux/Unix/Mac):

# change into generated directory structure
cd <FmuModelName>/build
# build the FMU in release mode
./build.sh release
# deploy the FMU, e.g. package the FMU in the zipped directory structure
./deploy.sh

System requirements / setup

The script runs with Python 2.7 and 3.x.

Linux

Simply install the python packages and pyqt5.

Ubuntu 16.04...20.04 - Python 2.7

> sudo apt install cmake build-essential qt5-default qt5-qmake qtcreator python-pyqt5 pyqt5-dev-tools p7zip-full

The package pyqt5-dev-tools contains the scripts pyuic5 and pyrcc5 needed for development of the FMIGenerator itself.

Ubuntu 16.04...20.04 - Python 3.x

> sudo apt install cmake build-essential qt5-default qt5-qmake qtcreator python3 python3-pyqt5 pyqt5-dev-tools p7zip-full

Ubuntu 21.04... - Python 3.x

> sudo apt install cmake build-essential qt5-qmake qtbase5-dev libqt5core5a libqt5concurrent5 libqt5gui5 libqt5network5 libqt5svg5-dev libqt5xml5 libqt5widgets5 python3 python3-pyqt5 pyqt5-dev-tools p7zip-full

Mac

Use homebrew and/or macports to install python and pyqt5 (or alternatively pip).

Windows

Things are bit more complicated for Windows. While the code can be compiled (thanks to the CMake build system) using quite a few build chains available on windows, the batch-scripts are currently expecting a standard Visual Studio 2022 installation and 7zip must be installed with 7za in the PATH. Also, cmake must be in in the PATH. You also need to install PyQt5 (via pip) as dependency of the script.

If your setup differs from that, edit the files build_VC_x64.bat and deploy.bat in directory data/FMI_template/build (there are example batch files for different VC versions).

License

The FMICodeGenerator is provided under a BSD 3-Clause License.

Developer Information

Directory Structure of the FMICodeGenerator repository

bin                 - batch/shell scripts to simplify/automate FMU generation
data                - resources and template files
doc                 - documentation, also includes examples
examples            - example directory structures (this is what the FMI generator should produce)
scripts             - the actual python scripts
scripts/third_party - external library and scripts
third_party         - external tools like the compliance checker