A sensor in a building HVAC system includes a transducer configured to measure a variable in the building HVAC system and to generate a sensor reading indicating a value of the measured variable. The sensor includes a communications interface configured to provide the sensor reading to a control device in the building HVAC system and a near field communication (NFC) circuit separate from the communications interface. The NFC circuit is configured to facilitate bidirectional NFC data communications between the sensor and a mobile device. The sensor includes a processing circuit having a processor and memory. The processing circuit is configured to wirelessly transmit data stored in the memory of the sensor to the mobile device via the NFC circuit, wirelessly receive data from the mobile device via the NFC circuit, and store the data received from the mobile device in the memory of the sensor.