Temperature measurement with temperature sensors Pt100 operates on the basis of the change in resistance of platinum as a function of temperature fluctuations. The electrical connection is made by a 2, 3 or 4-wire system, depending on the input of the display unit. As an optional alternative these temperature sensors can be connected to a 4-20mA current input by means of an integral two-wire transducer mpu-4, -4p (two-wire current loop). The temperature sensor TFP-17 is suitable for measurements of gaseous media like air.