An automation technology field device, comprising: - A connection terminal for connecting a two-wire cable; - field device electronics which provide a maximum operating power (Pmax) through the two-wire cable via the connection terminal, wherein the field device electronics are configured to perform a main function of the field device, in particular the detection of measured values or limit values; - an internal interface provided by the field device electronics for connecting an electronic module; - the electronic module with at least one electronic component for performing an additional function, wherein the at least one electronic component of the electronic module is connected to the field device electronics via the internal interface for data transfer, and wherein the internal interface of the at least one electronic component also provides a main power (Phaupt); - a capacitance associated with the electronic module, which is configured in such a way that the capacitance is charged via the internal interface and provides an additional first auxiliary power to the at least one component in the event that the at least one component of the electronic module has an energy demand which exceeds the main power (Phaupt); - a battery associated with the electronic module, which is configured in such a way that the battery provides a second auxiliary power to the at least one component in the event that the at least one component of the electronic module has an energy demand which exceeds the main power (Phaupt) and the first auxiliary power, wherein the capacitance and the battery are adapted to each other in such a way that the battery of the at least one component only provides the second auxiliary power if the main power (Phaupt) and the first auxiliary power do not supply sufficient power to the at least one component; - a current-limiting circuit, which is connected to the internal interface at one input and to the at least one component of the electronic module at one output, and is configured to limit a current which flows via the internal interface to a specific current value (Imax), characterized in that the capacitance and the battery are arranged between the output of the current-limiting circuit and the at least one component and are adapted to each other in such a way that the battery of the at least one component only provides the second auxiliary power if an output voltage at the output of the current-limiting circuit falls below a specific value. - A connection terminal for connecting a two-wire cable; - field device electronics which provide a maximum operating power (Pmax) through the two-wire cable via the connection terminal, wherein the field device electronics are configured to perform a main function of the field device, in particular the detection of measured values or limit values; - an internal interface provided by the field device electronics for connecting an electronic module; - the electronic module with at least one electronic component for performing an additional function, wherein the at least one electronic component of the electronic module is connected to the field device electronics via the internal interface for data transfer, and wherein the internal interface of the at least one electronic component also provides a main power (Phaupt); - a capacitance associated with the electronic module, which is configured in such a way that the capacitance is charged via the internal interface and provides an additional first auxiliary power to the at least one component in the event that the at least one component of the electronic module has an energy demand which exceeds the main power (Phaupt); - a battery associated with the electronic module, which is configured in such a way that the battery provides a second auxiliary power to the at least one component in the event that the at least one component of the electronic module has an energy demand which exceeds the main power (Phaupt) and the first auxiliary power, wherein the capacitance and the battery are adapted to each other in such a way that the battery of the at least one component only provides the second auxiliary power if the main power (Phaupt) and the first auxiliary power do not supply sufficient power to the at least one component; - a current-limiting circuit, which is connected to the internal interface at one input and to the at least one component of the electronic module at one output, and is configured to limit a current which flows via the internal interface to a specific current value (Imax), characterized in that the capacitance and the battery are arranged between the output of the current-limiting circuit and the at least one component and are adapted to each other in such a way that the battery of the at least one component only provides the second auxiliary power if an output voltage at the output of the current-limiting circuit falls below a specific value.