Continuous and discrete components can be integrated in diverse systems including defense, medical, electronic, communication, and automotive applications. Given the heterogeneity of concepts that have to be taken into consideration, their design involves overcoming specific global modeling and validation challenges. This paper presents semantics for model-based validation of continuous/discrete systems. It focuses on the simulation interfaces semantics, representation and verification. The proposed approach is applied for the validation of a continuous/discrete medical system, an automatic glycemia level regulator.