As mentioned there is a need for somewhere to decide: how to connect models, the topography of the total system and or interactions between slaves in an easy way without needing to change the slaves themselves. This task falls to the Function unit, which contains functions for output variables that are dependent only on input variables and may not be dependent on time, as the Function unit only handle signals from the slaves which occurs in the macro time step. An important feature of the Function unit is that all output variables are calculated between time steps based on the input variables, which means that there will not be a time step delay as is the case for the slaves. Function units may also include change in system behavior that can be modeled without any dynamics, like a breaker in a switch board.


  1. Use Function Units for tasks that are independent of time in order to avoid the macro time-step delay