Analog multiplexers (Mux) are electronic devices that connect analog input signals in sequence like a rotary switch to an output. For further processing in a PLC/PC/controller, only one analog input has to be purchased. Switching through can take place in a fixed time cycle or by addressable selection of the desired input.
 

In particular, MOTRON manufactures multiplexers for PT100 temperature sensors or for general analog signals 0 - 10 V.

TAMP 4 G3 Temperature Multioplexer for 4 PT-100 Inputs	TAMP 4 VF Temperature Multioplexer for 4 PT-100 Inputs	TAMP8-G3 Temperature Multioplexer for 8 PT-100 Inputs	SAMP 8/71 Universal Analog Signal Multioplexer for 8 analog Inputs. Mehrere Geräte sind kaskadierbar.

Read more..  http://www.motron.de/de/produkte/sensor-und-regeltechnik/analog-multiplexer