A method of diagnosing a temperature sensing system having a temperature sensor, a field processing module coupled to the temperature sensor, a bitbus, a fieldbus, and an auxiliary processing module communicating with the bitbus and the fieldbus. The method includes generating a temperature characteristic at the temperature sensor, processing the temperature characteristic at the field processing module, and generating field operating data including a temperature diagnostic parameter as a function of the temperature characteristic. The method also includes communicating the field operating data including the temperature diagnostic parameter over the bitbus from the field processing module to the auxiliary processing module, generating at the auxiliary processing module auxiliary field data as a function of the received field operating data, and communicating the auxiliary field data over the fieldbus.