How to reduce timestep in response to external function throwing exception

Question

I have a Modelica model that calls an external function. If the time step is too large, often the external C++ code throws an exception.

It seems like the proper thing to do in response would be to reduce the time step and try again. Is there a way to reduce the timestep in response to an exception?

Answer 1

There is no direct standardized way, but you can catch the exception and either return it as an error flag to Modelica and use assert, or use ModelicaError in a C-wrapper (using ModelicaError in the catch-part in C++ might be possible).

The specification states that after a failed assertion (or call of ModelicaError) the simulation may continue with another evaluation e.g., with a shorter step-size, or by changing the values of iteration variables.