<p>The box (100) has a field device connector (101) for connecting the box to a field device (109) e.g. pressure measuring device. An interface connector connects the box to an interface adapter (103). The connectors are coupled to each other in a communicatable manner for transmission of a signal. The interface connector directly connects the box to a display and operating device. An adapter plug has a coded contact such that an improper connection of the plug to the field device is prevented. A power supply self-sufficiently supplies the interface adapter with electrical energy. An independent claim is also included for a method for transmission of a signal between a field device and an operating device.</p>
