Modeling Guide
Knowledge Guides /How do you deliver Modelica and FMI co-simulation, and can FMUs run across tools?
Last updated: · New Horizon Digital Outsourcing Team
An FMU is one delivery format for model exchange or co-simulation, but being able to export an FMU does not mean it will run in every tool and on every platform. Agree on the FMI version, interface type, operating system, runtime dependencies, variable units, and acceptance scenarios, then verify an actual import in the target environment.
Distinguish source models, interface standards, and runtime environments
- Modelica expresses physical system models, while FMI defines interfaces and packaging rules for exchanging dynamic models. Source projects, exported FMUs, external libraries, and commercial tool licenses are separate assets and should be listed separately in the contract.
- Model Exchange and Co-Simulation assign solver responsibilities differently. When selecting an approach, confirm which environment handles integration, how time advances, whether events can be handled, and which capabilities the target importing tool supports.
What fields must an interface table include?
- For every input and output, record its physical meaning, unit, positive direction, range, initial value, and sampling convention. Variables such as temperature or torque may have identical names yet produce incorrect results because their units or reference directions differ.
- Specify the communication step size, event synchronization, initialization order, and stopping conditions. If a coupled model oscillates, distinguish physical phenomena from solver issues and interface delays, rather than simply adjusting parameters to flatten the curves.
How can reproducibility be demonstrated?
- Select representative steady-state, transient, and abnormal-input scenarios, and retain parameters, solver settings, run logs, and output baselines. Check step-size sensitivity for key results and explain how errors are compared.
- Reimport and run the model in the recipient's environment, checking required binary libraries and licenses. Running only on the developer's computer does not demonstrate a completed handover across environments.
How can the outsourcing scope be made actionable?
- Specify model boundaries, required source files, target platforms, and licensing responsibilities. For components supplied only as black-box FMUs, identify adjustable parameters, observable variables, and maintenance responsibilities.
- Start by establishing co-simulation with two or three components before expanding to the full system. Assess strongly coupled components and discontinuous events separately; do not estimate all integration work through simple proportional scaling.