20-Channel General Purpose, Solid-State Multiplexer 450 ch/s scanning Two- and four-wire scanning Built-in thermocouple reference junction 120 V switching Includes Certificate of Calibration The DAQM900A module is divided into two banks of 10 two-wire channels each. All 20 channels switch both HI and LO inputs, thus providing fully isolated inputs to the internal DMM or an external instrument. During 4-wire resistance measurements, channels from Bank A are automatically paired with channels from Bank B to provide the source and sense connections. The module has a built-in thermocouple reference junction to minimize errors due to thermal gradients when measuring thermocouples. Two- and four-wire channels can be mixed on the same module. Capable of measuring voltage ac/dc, frequency/period, 2/4-wire resistance, and temperature with thermocouple and thermistor sensors.