Analog Resistive Sensors - 150/300/600 Ohm

Hello,

A number of the Siemens analog input modules for the S7-300 (and I assume 1200, 1500) have options for selecting 150, 300 or 600 Ohm resistance sensors, that function similar to the PT100 type RTD's (potentiometers would probably also fall under this category). I have been searching but have not come across any sensors with this behavior (process value between 0 and 150 Ohms, for example). Does anyone know what these type of inputs are commonly used for? Are these certain types of RTDs or are they designed for specific potentiometer inputs or something?

Thanks!

150 ohms is about 150 celsius on a Pt100
so the scale runs from -200 to 150
they just get the resistance from the voltage input with a current of 1 mA
and then calculte the Celsius.
very common and simple to make.