1. I am using Max31865 , resistance to digital converter for interfacing PT100. (for 2 wire & 4 wire only) 2. I want to multiplex 8 rtd to it so that I don't have to use separate IC for each. 3. I have searched for analog mux like ADG708(internal resistance is 3 ohm) & DG408(RDS = 100ohm). 4.They have large internal resistance. I think these will effect the acuracy of PT100 since it have 0.4ohm/C. 5. Or they won't effect the accuracy since I am using PT100 is 4 wire configuration so drop across wires won't effect the accuracy? 6. Also for 2 wire configuration, I will use it as 4 wire only by connecting two RTD wires across RTD+ & RTD- & shorting FORCE+ with RTD+ & FORCE- with RTD-. 7. Schematic is attached. What should be best way to multiplex. 8. I think I will need 3 (8:1) multiplexer as shown in schematic. Because 4 wire of all RTD can be shorted together. Or I should use 4 (8:1) mux.