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FMU Export

FMI Kit provides two Simulink Coder targets to export Simulink models as FMUs:

  • grtfmi.tlc (based on the Generic Real-Time target)
  • rtwsfcnfmi.tlc (based on the S-function target)

The table below gives an overview of the different capabilities:

GRT S-Function
MATLAB Version R2012b - R2019a R2012b - R2018b
Model References yes no
Source Code yes no
Co-Simulation yes yes
Model Exchange no yes
Requires CMake yes no

Supported compilers

grtfmi.tlc: all compilers supported by CMake

rtwsfcnfmi.tlc: all Visual Studio versions supported by MATLAB on Windows or GCC on Linux

Exporting an FMU

To export a Simulink model as an FMU

  • open the model to export (e.g. type f14 in the command window)
  • add external inputs and outputs (optional)
  • open Simulation > Model Configuration Parameters (CTRL+E)
  • under Solver > Type select Fixed-step for a Co-Simulation FMU or Variable-step for a Model Exchange FMU
  • under Code Generation > System target file click Browse and select grtfmi.tlc for a Generic Real-Time based FMU or rtwsfcnfmi.tlc for an S-function based FMU
  • set the respective FMI options (optional)
  • apply the Model Configuration Parameters dialog
  • select Code > C/C++ Code > Build Model (CTRL+B) to export the FMU to the current working directory

Coder target

Generic Real-Time Target based FMU

The grtfmi.tlc target has the following options under Simulation > Model Configuration Parameters > FMI:

Parameter Description
CMake generator CMake generator to build the shared library
CMake command CMake command or path the executable (leave empty for default command)
Visible parameters Parameters to include in the model description (leave empty to include all)
Include sources in FMU Add model sources to FMU

S-Function based FMU

The rtwsfcnfmi.tlc target has the following options under Simulation > Model Configuration Parameters > FMI:

Parameter Description
FMI type specifies FMI type (ModelExchange or CoSimulation)
Model author specifies model author for FMU XML description
Generate black-box FMU selects if the FMU should be generated as a black box (only inputs and outputs)
Include block hierarchy in variable names selects if variable names of the FMU XML should use block hierarchy notation
Include global block outputs selects if block outputs should be included in FMU XML description
Include discrete states (DWork) selects if discrete states and modes should be included in FMU XML description
Export image (.png) of Simulink model to FMU resources selects if an image of the Simulink model should be exported with the FMU
Copy Simulink model to FMU resources selects if the whole Simulink model should be copied to the FMU
Load S-functions from binary MEX files selects that S-functions in the model will be loaded from pre-compiled binary MEX files instead of using stand-alone compilation of S-function sources. This option will create dependencies on MATLAB binaries, which are not included in the exported FMU. On Windows, the FMU will by default try to load these from the bin directory of the exporting MATLAB installation. The environment variable SFCN_FMI_MATLAB_BIN can be used to specify a different directory from where to load the MATLAB binaries (for example a MATLAB run-time installation). On Linux, it is required to use the environment variable LD_LIBRARY_PATH to specify the path to the MATLAB binaries. The S-function MEX files used by the model are copied to /resources/SFunctions of the FMU and are loaded automatically when the FMU is instantiated.
Additional S-function sources List of additional user source files for stand-alone S-function compilation. Should be used instead of Custom Code > Source Files to ensure that the correct compiler options are used
Compiler optimization flags User-defined optimization flags to be used by the compiler (default: /O2 /Oy - for Visual Studio on Windows and -O2 for GCC on Linux)

It is recommended to set the Tasking mode to SingleTasking.

Limitations and Trouble-Shooting

  • This version of the package supports 32- and 64-bit MATLAB releases from R2010a to R2018a.

  • On Windows, the package supports Visual Studio 2008 (9.0) and later compilers as supported with the respective MATLAB releases.

  • On Linux, the package should support the versions of gcc supported with the respective MATLAB releases. The object files shipped in the package have all been compiled using gcc 4.5.4

  • The FMU is compiled with dynamic loading of the C run-time on Windows. This may require installation of corresponding Visual Studio redistributables on the target platform.

  • The option Include block hierarchy in variable names could in very rare cases give rise to name conflicts in the XML variable names. For example, any special characters in Simulink block names will be converted to underscore which may lead to name conflicts. It is recommended to avoid using special characters in block names with this option (carriage return and space are safe to use).

  • The variable names for continuous-time states, discrete states, parameters, and block outputs are separated in the top-level categories ContStates, DiscStates, Parameters, and BlockOutputs in the structured view. This is to ensure unique variable names in the FMU XML file, since variable names from different categories are not guaranteed to be unique within a block. In the flat view, the variable names are appended with _xc, _xd, _pm and _wb respectively.

  • For multiple instances of conditionally executed non-virtual subsystems or Stateflow charts, it is required to select Treat as atomic unit and set Function packaging to Inline for the subsystems/charts.

  • S-functions in the exported model are not allowed to call into the MATLAB environment, e.g. using mexCallMATLAB or mexEvalString.

  • The FMU export target is not model reference compliant.

  • The package is subject to the same limitations as the standard S-Function target.