The typical factory automation system contains a number of programmable automation devices such as robots, automatic storage/retrieval systems (AS/RSs) and automatically guided vehicles (AGVs). Real-time control system software (RTCS) is needed for integrating these devices into a synchronized manufacturing system (SMS). However, development of this RTCS software could be hampered by excessively long software development backlogs which are currently averaging about 30 months in the typical US corporation. This paper presents a structured methodology for the development of the specifications for such software. This methodology is illustrated by applying it to an automated system for producing highway traffic signs. This system consists of an assembly robot with an automatic tool changer, an AS/RS and a reciprocating table