Thermocouple Measurements - Agilent Technologies 34972A User Manual

Chapter 4 Features and Functions
Temperature Measurement Configuration

Thermocouple Measurements

To connect a thermocouple to the module's screw terminals, see page 28.
• The instrument supports the following thermocouple types:
B, E, J, K, N, R, S, and T using ITS-90 software conversions.
The default is a J-Type thermocouple.
• Thermocouple measurements require a reference junction
temperature. For the reference junction temperature, you can use an
internal measurement on the module, an external thermistor or RTD
measurement, or a known fixed junction temperature.
• If you select an external reference, the instrument automatically
reserves channel 01 on the multiplexer in the lowest slot as the
reference channel (thermistor or RTD measurement). If you have
more than one multiplexer installed, channel 01 on the module in the
lowest slot is used as the reference for the entire instrument.
• Before configuring a thermocouple channel with an external
reference, you must configure the reference channel (channel 01) for a
thermistor or RTD measurement. An error is generated if you
attempt to select the external reference source before configuring the
reference channel. An error is also generated if you change the
function on the reference channel after selecting the external
reference for a thermocouple channel.
• If you select a fixed reference temperature, specify a value between
-20 °C and +80 °C (always specify the temperature in °C regardless of
the temperature units currently selected).
• The accuracy of the measurement is highly dependent upon the
thermocouple connections and the type of reference junction used.
Use a fixed temperature reference for the highest accuracy
measurements. The internal isothermal block reference provides the
lowest accuracy measurements. For more information on reference
junction temperature measurements and associated errors, see the
sections on pages 267 and 274.
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