Keithley differential multiplexer plug in module 770x series keithley 7702 the keithley 7702 is a 40 channel differential multiplexer plug in module that offers 40 channels of 2 pole or 20 channels of 4 pole multiplexer switching that can be configured as two independent banks of multiplexers the 7702 provides two additional protected channels for current measurements it is ideal for rtd thermistor and thermocouple temperature applications keithley 7702 dual 1x20 multiplexer card