HWIL development workflow

A typical HIL/HWIL development workflow starts with Simulink models and ends with code deployed on hardware with software that is expected to run in real time:

If there are differences between Simulink and Visual Studio runs, most of the time it is due to you forgetting to equalize all inputs. If you are sure about inputs being the same, the remaining sources of difference are details of floating point representations and sometime a block in Simulink generating wrong code. For example Aerospace blockset ECEF2LLA block code results in latitude lagging one time step behind, which does not occur during a Simulink run.

If there are differences between software running on hardware and Visual Studio results, it might be an indication of insufficient stack size allocation or tasks not meeting their deadlines. If you are lucky and have an advanced real time OS like VxWorks, it might throw a segmentation violation if there is too little stack available. If you don't want to count on luck, you have to test thoroughly, preferably using automated tests.