  Adaptive and flexible production systems require modular and reusable
software especially considering their long term life cycle of up to 50 years.
SWMAT4aPS, an approach to measure Software Maturity for automated Production
Systems is introduced. The approach identifies weaknesses and strengths of
various companie's solutions for modularity of software in the design of
automated Production Systems (aPS). At first, a self assessed questionnaire is
used to evaluate a large number of companies concerning their software
maturity. Secondly, we analyze PLC code, architectural levels, workflows and
abilities to configure code automatically out of engineering information in
four selected companies. In this paper, the questionnaire results from 16
German world leading companies in machine and plant manufacturing and four case
studies validating the results from the detailed analyses are introduced to
prove the applicability of the approach and give a survey of the state of the
art in industry.
