A temperature controller for a heater for a container for use in hazardous areas and a method of programming such a temperature controller. The method of programming such a temperature controller comprises the steps of writing identification data and parameter data to a memory of a portable token in an area remote from the hazardous area; transporting the token to a position in proximity to the temperature controller in the hazardous area; transmitting, by means of near field communication, the identification data and parameter data stored in the memory of the portable token to a receiver in the temperature controller; comparing the identification data received by the temperature controller with identification data stored in a memory of the temperature controller; and if said comparison of identification data is positive, and updating parameter data stored in the memory of the temperature controller with the parameter data received by the receiver.
