In this paper, we propose an extension of classical finite state machine as it called a timer embedded finite state machine (TEFSM) with its formal modeling methods. In the proposed state-based approach, a discrete event system is modeled as a coupled TEFSM. Also presented is a systematic procedure and architecture of developing a simulation executor with a synchronization manager for the coupled TEFSM model. A TEFSM toolkit for
modeling and simulation of the proposed TEFSM model has been implemented and a ping pong system was developed as an illustrative example.