The master interface module adds a DP master interface to the IM 151-7(F-)CPU / IM 151-8(F) PN/DP CPU. The functionality and quantity structures are defined by the IM 151-7 (F-)CPU / IM 151-8(F) PN/DP CPU.

The master interface module also enables connection of a programming device to its interface. This makes routing to bus nodes possible on the integral CPU interface possible if it is operated in active mode.