The present disclosure relates to an adapter for a 2-wire field device, especially a 2-wire field device of process and/or automation technology, comprising a communication unit for, especially wireless, especially bi directional, communication with an external unit, and an energy storage unit for supply of at least the communication unit with electrical energy. According to the present disclosure, the adapter includes a first connection element for, especially electrical, contacting of the adapter with a second, first connection element complementary, connection element of the field device, wherein the at least two connection elements are embodied for supply of at least the adapter with electrical energy and for exchanging information. Furthermore, the present disclosure relates to a transmitter with an adapter of the present disclosure as well as a 2-wire field device having an adapter of the present disclosure or a transmitter of the present disclosure.