A methodology based on transformation schemm which is an extension of data flow diagram has solutions to the well-known problems of real-time sotware development: Timing and control aspects of real-time systems are satisfied and token-based execution is used. A scheme to support the methodology under ISLDM/SEM environments has been carried out with the premises that automated support are invaluable in the case of large complex systems such as real-time systems. An automated support tool for the methodology(TSMRTS) has been successfully applied to a command, control, communication, and intelligence(C3I) system. Consistency checking is friendly and documentation is neat and up-to-date. Although completeness is never satisfied, it is increased through report review and automated execution. The automated execution of transformation schema shows more ease and effectiveness than token-based execution.