We describe a framework that constructs interfaces between simulation tools and real-time prototyping hardware in a high-level DSP synthesis environment. A goal of this work is to abstract the concept of the interface so that customized links are not required between each simulation and hardware engine. To support a new engine, the DSP system designer must define two pairs of communication primitives between the new tool and host workstation. The interface construction mechanism provides incremental compilation of subsystems in a system specification into the high-level DSP synthesis environment. We illustrate this framework with practical examples that have been constructed in Ptolemy.