Software development for PLC based systems is changing. In addition to the traditional, procedural programming languages for Programmable Logic Controllers (PLCs) from the IEC 61131-3, increasingly object-oriented elements are used, as defined in the object-oriented extension of IEC 61131-3. This paper discusses observed effects of the change on the usability of design methods for software developers. Subsequently, a model-driven, tool supported approach for automation systems is presented. Finally, an outlook on the next steps for the realization of the underlying concept is given.