  Automated Production Systems (aPS) have lifetimes of up to 30-50 years,
throughout which the desired products change ever more frequently. This
requires flexible, reusable control software that can be easily maintained and
evolved. To evaluate selected criteria that are especially relevant for
maturity in software maintainability and evolvability of aPS, the approach
SWMAT4aPS+ builds on a questionnaire with 52 questions. The three main research
questions cover updates of software modules and success factors for both
cross-disciplinary development as well as reusable models. This paper presents
the evaluation results of 68 companies from machine and plant manufacturing
(MPM). Companies providing automation devices and/or engineering tools will be
able to identify challenges their customers in MPM face. Validity is ensured
through feedback of the participating companies and an analysis of the
statistical unambiguousness of the results. From a software or systems
engineering point of view, almost all criteria are fulfilled below
expectations.
