The Functional Mock-up Interface (FMI) is an API standardization for exchanging dynamic system models.

You can use FMI to decouple modeling environments from model consumers. This decoupling helps create tool-agnostic, portable solutions between modeling and simulation environments. For more information, refer to the FMI website.

The FMI standard defines the following model interaction patterns:
  1. Model Exchange—The package contains the mathematical representation of the model and the simulation environment solves the equations of the model
  2. Co-Simulation—The model contains the solver for the model and can directly provide outputs based on inputs and time slice.
  3. Scheduled Execution [Supported only in FMI 3.0] —The model contains partitions that can be activated concurrently by an external scheduler.

FMI also defines the distribution packaging of the model and decouples the interface description from the actual model binaries. You can have support for several platforms, like Windows 64-bit, Linux 64-bit, and source code in the same package. A model that implements this interface is called a Functional Mockup Unit (FMU).