Although a lot of research has taken place in Object Oriented Design of software for Real Time systems and mapping of design models to implementation models, these methodologies are applicable to systems which are less complex and small in source code size. However, in practice, the size of the software for real time applications is growing. The run time architecture of real time applications is becoming increasingly complex. In this paper, we present a generic approach for mapping the design models to run time architectures resulting in combination of processes and threads. This method is applied in development of a communication subsystem of C4I complex and shall be presented as a case study.