This paper deals with a behavioral interpretation of physical systems. It d
escribes how we can interpret the systems current state using a multimodeli
ng principle. The purpose of this interpretation task is to explain what is
happening in the system from a small set of observations in terms of funct
ional states of the system processes. The model types considered are functi
onal and qualitative models generated according to a bond graph description
. The functional model (process model) is contructed taking into account th
e causality and the orientation of the energy flow considered in the bond g
raph. We cooperate this model with a qualitative causal graph in order to i
dentify the system process functional states.