The MC3324 is a mixed multiplexer with 20 voltage channels and 4 current channels. The 20 voltage channels (from channel 01 to channel 20) are divided into two banks of 10 two-wire channels each and can be used for 2-wire and 4-wire connections. When making 4-wire resistance measurement, the instrument automatically pairs channel n with channel n+10. 4 current channels (from channel 21 to channel 24) are used to measure DC current or AC current. Mixed Multiplexer Module is used with the external terminal block (M3TB24) which has a built-in thermocouple reference junction.