Earth moving equipment and other heavy machinery for environmentally harsh conditions are controlled by a control panel supplied with a lock, and such panels are frequently removable to prevent theft or unauthorized operation. The interface is in the form of a plug-and-socket, the parts of which have to be sealed against dust and humidity when not interfacing. In order to prevent wear and to assure reliable control, according to the invention, no part of the connection between the control panel and a receptable is galvanic, the power supply for the control panel is wireless, such as inductive or optical, while communications may occur by means of a two-way radio protocol or by optical means.