The authors present an approach for automatic communication system development and discuss a semiautomatic implementation of a real-world communication system. They give a generalized communication system framework (GCSF), which is a universal environment for various communication systems. They introduce a layered communicating finite state machine (LCFSM) to specify communication systems. Given an LCFSM, a communication system generator can automatically produce an executable communication system, based upon the GCSF. The communication system generator is a process of developing communication systems. A communication system generator was implemented on DOS and UNIX environments, yielding a communication system with several real-world protocols from the DoD and the IEEE 802 protocol standards organizations.< >