An electronics module for coupling to a module arrangement, in particular valve island, in a line-up direction, comprises a casing which comprises a front side, a back side, an upper side, a bottom side and two opposite lateral surfaces extending along the line-up direction in relation to a state mounted on the module arrangement. In the casing an electronics is accommodated and at least a first bus connection and two second bus connections are provided, which are connected to the electronics within the casing. The at least one first bus connection is arranged either on the upper side or on the bottom side, while a second bus connection is arranged on each of the lateral surfaces, respectively. A module assembly comprises a module arrangement, in particular a valve island, and an electronics module, wherein the electronics module directly abuts on the module arrangement in the line-up direction, and is detachably connected thereto in a non-destructive manner.