Initialization

According to the FMI for Co-simulation specification, the importing environment may alter the value of the scalar variables that have a start  value. These changes can be applied between the instantiation step and the initialization step of the FMI import process.

In Simcenter Amesim, parameters (including global parameters) can be defined through expressions that depend on the value of other global parameters. If a parameter is defined by such an expression, the corresponding FMI scalar variable does not have a start value. It is said to be a dependent parameter , which value is computed during the initialization using the value of the independent parameters . Consequently, only the independent parameters, i.e. having a literal default value in Simcenter Amesim, are mapped to scalar variables with start value. Their value can be changed by the importing environment between instantiation and initialization. The other dependent parameters are present in the FMU, which means that their value can be read by the environment but cannot be changed at runtime. The read-only status of these parameters defined by expressions avoids breaking mathematical dependencies during initialization.