A measuring apparatus, a physiological sensor, and an interface unit for determining blood parameters of a subject are disclosed. The sensor (210) comprises an emitter unit (211) comprising a first plurality of emitter elements (213, 214) configured to emit radiation at a second plurality of wavelengths and a detector unit (214) configured to receive radiation generated by the emitter unit and transmitted through tissue of the subject. The sensor further comprises a sensor memory (216) storing sensor-specific information about the sensor unit, wherein the sensor-specific information includes at least calibration data for a given measurement mode, and a memory access interface (217) for enabling an entity (231, 236 237) external to the sensor to update at least part of the sensor-specific information in a sensor ability update process, thereby to update ability of the sensor unit to operate in the given measurement mode.
