Anticipation capability, responsiveness as well as the ability to deal with changes have become key factors of manufacturing companies. These developments directly affect factory planning. Factories need to provide a constant and responsive adaptability. This paper contributes to the adaption of the planning process with regard to the key factors. Modularization of the production system is one aspect of addressing the described challenges, the planning process itself has to be adapted to modular factory structures.The question to answer is which variation of production system modules is most appropriate in specific conditions. Today’s planners lack a tool that enables them to make the right decision about the configuration of the factory. This paper proposes a configuration logic for the modularized production system. The logic intends to generate an optimally configured production system. Furthermore the developed Variant Fields offer the possibility to apply the configuration logic within the planning process in practice. In a Variant Field features of a module of the production system (e.g. room utilisation factor) are related with one another, which span a two-dimensional field. Each axis is divided by different characteristic values of variants of a module. According to the characteristic values along the axles different areas within the Variant Field are determined. These areas are thus linked to the variants of a module. For the configuration of the production system, its requirements in the two features of the Variant Field then are marked in it. The variant is selected according to the area in which the marking falls. In the paper the methodology and the use of Variant Fields will be explained. In order to do so, the configuration of logistic systems is used as an example for illustration.