A method or system for operating a field transmitter F, in which a application program FA communicates with a field-transmitter s specific software module SW1, SW2, or SW3. The communication is by a defined interface S in order to call standard functionalities of the field transmitter F. An expansion module EW for the application program is provided which is interposed between the application program FA and the field-transmitter specific software module SW1, SW2, or SW3 in order to permit additional functionalities within the context of and using the field-transmitter specific software module SW1, SW2, or SW3.