A module arrangement for a modular field device connection unit comprises a frame module having an interface receptacle, an interface module adapted to be inserted into the interface receptacle along a module insertion path, and a resetting mechanism adapted to reset the movable coding element into the neutral position by insertion of the interface module into the interface receptacle and/or removal of the interface module from the interface receptacle. The interface module has a cartridge receptacle and a movable coding element. The movable coding element is movable from a neutral position into a coding position by insertion of a cartridge member into the cartridge receptacle. The resetting mechanism has a trigger element at least partially protruding into the module insertion path.