Input/output station for a field bus system, field bus coupler for the input/output station, and placeholder module for the input/output station

An input/output station for a fieldbus system with a fieldbus coupler, which has a system bus interface and a fieldbus interface, the input/output station comprising a plurality of slots for pluggable input/output devices, wherein one or more placeholder devices are also pluggable into the plurality of slots besides the input/output devices, wherein an empty slot is also admissible for the plurality of slots, wherein the fieldbus coupler comprises firmware which is configured for a full configuration of the input/output station, wherein the firmware is configured to communicate with a control station in such a way that the fieldbus coupler receives the full configuration of the input/output station as a planned target configuration from the control station, and in that the firmware is configured to confirm a full configuration of the input/output station in an operating mode irrespective of the actual occupancy of the input/output station with the pluggable input/output devices of the control station.