step simulation

HelloI need to embed the FSim into a more complex environment. I need a step by step simulation feature: Fsim does a step, the rest of the environment does a step...and so on. Can this be realized and what is about the timescale? Can the Fsim be stopped and its internal simulation time be freezed?? The environment uses a simulation steptime of 55 ms. But the environment needs different amount of realtime to do one 55ms step, so the time while the FSim needs to pause will vary. This may be a problem if its internal clock is not freezed, I think. Do you know of any tutorials about such a feature or has anybody realized something like that?thx in advanceTweety