Configuration detection for a sensor assembly

Methods, systems, and apparatus for detecting configuration for a patient worn sensor assembly are described. In one aspect a method includes receiving, by a computer system, sensor assembly data for a particular sensor assembly, accessing, by the computer system, sensor assembly identifier information defining a plurality of sensor assembly identifiers, where each sensor assembly identifier is associated with a respective sensor assembly, identifying, by the computer system and based on the sensor assembly data, a particular sensor assembly identifier for the particular sensor assembly, and determining, by the computer system, configuration information for the particular sensor assembly based on the particular sensor assembly identifier.