A process variable transmitter comprising a housing with a transmitter chamber and a terminal chamber sealed from the transmitter chamber by a sealing cap, with a terminal block in the terminal chamber for connecting to a two-wire process control loop, the process variable transmitter comprising: transmitter circuitry in the transmitter chamber for determining a process variable from a sensor signal produced using a process sensor, the transmitter circuitry comprises at least one operating parameter, wherein a signal on the two-wire process control loop is conveyed to the transmitter circuitry along first pins (226, 228) which extend through the sealing cap; and a wireless communication module in the transmitter chamber configured to be powered by the two-wire process control loop and capable of communicating wirelessly with a general-purpose mobile device using a general-purpose wireless communication standard such that the wireless communication module can instruct the transmitter circuitry to change a value of the at least one operating parameter based on a wireless message received from the general-purpose mobile device; and the process variable transmitter further comprises a power storage component within the terminal chamber, said power storage component being connected to the wireless communication module via second pins (230, 232) which also extend through the sealing cap, the power storage component configured to provide additional power to the wireless communication module; and wherein the wireless communication module is configured to route a portion of power from the two-wire process control loop back to the power storage component when the wireless communication module is inactive and draw additional power from the power storage component to the wireless communication module when the wireless communication module is active. transmitter circuitry in the transmitter chamber for determining a process variable from a sensor signal produced using a process sensor, the transmitter circuitry comprises at least one operating parameter, wherein a signal on the two-wire process control loop is conveyed to the transmitter circuitry along first pins (226, 228) which extend through the sealing cap; and a wireless communication module in the transmitter chamber configured to be powered by the two-wire process control loop and capable of communicating wirelessly with a general-purpose mobile device using a general-purpose wireless communication standard such that the wireless communication module can instruct the transmitter circuitry to change a value of the at least one operating parameter based on a wireless message received from the general-purpose mobile device; and the process variable transmitter further comprises a power storage component within the terminal chamber, said power storage component being connected to the wireless communication module via second pins (230, 232) which also extend through the sealing cap, the power storage component configured to provide additional power to the wireless communication module; and wherein the wireless communication module is configured to route a portion of power from the two-wire process control loop back to the power storage component when the wireless communication module is inactive and draw additional power from the power storage component to the wireless communication module when the wireless communication module is active.