British electricals supplies 2-wire temperature transmitter, which are available in different models for rtd and thermocouples in head mounting and din rail mounting, and isolated and non-isolated types. Measuring signal of sensors is transformed into standardized load of independent 4-20 ma dc, which is linearly proportional to the measured temperature. Calibration is carried out by the temperature transmitter through dip switch array, jumper and by pc configurable with hart protocol, depending on model selected, while zero and span are done by multi-turn potentiometer. Some models of the temperature transmitter are also available certified as inherently safe according to the relevant standards, when connected via an approved barrier.