Importing and using FMU > The Import Tool in detail > Import submodel-specific parameters
Co-simulation specific parameters
These parameters are only present in import submodels that wrap FMU for Co-simulation.
| Parameter name | comType |
|---|---|
| Parameter title | co-simulation step specification |
| Allowed values | time step size multiple of master fixed step size |
| Initial value | time step size |
| Default value | time step size |
| Meaning | This value depends on the type of numerical integrator chosen in the Run Parameters dialog box: if the Standard integrator (i.e. variable-step size solver) is enabled, it has to be set to time step size, and the comStepSize parameter (see below) is used to specify directly the co-simulation step size in seconds. if the Fixed step integrator is enabled, it has to be set to multiple of master fixed step size, and the comNbStepSize is used to specify the co-simulation step size as an integer multiple of the solver step. |
| Parameter name | comStepSize |
|---|---|
| Parameter title | co-simulation step size |
| Allowed values | a strictly positive real number expressed in second |
| Initial value | 0.001 s |
| Default value | 0.001 s |
| Meaning | Only allowed if comType is set to time step size. This is the step size that the master simulator (here Simcenter Amesim) uses for performing co-simulation steps with the slave FMU. |
| Parameter name | comNbStepSize |
|---|---|
| Parameter title | FMI 1.0, 2.0 and 3.0 without fixed internal step size: a multiple of the master fixed step size FMI 3.0 with fixed internal step size: a multiple of the FMU fixed-step size, followed by its value expressed in seconds |
| Allowed values | a strictly positive integer number |
| Initial value | 1 |
| Default value | 1 |
| Meaning | FMI 1.0, 2.0 and 3.0 without fixed internal step size: only allowed if comType is set to a multiple of the master fixed-step size. The actual co-simulation step size is obtained by taking the product of this parameter with the fixed-step size of the numerical integrator FMI 3.0 with fixed internal step size: always active. The actual co-simulation step size is obtained by taking the product of this parameter with the internal step size of the FMU |
Source: https://docs.sw.siemens.com/en-US/doc/254352342/PL20250521841123434.amesim_collection.Functional_Mockup_Interface/Cosimulation_specific_parameters · retrieved 2026-07-17