5. Press Integrate Settings softkey to select whether the measurement integration time will be specified
in terms of Number of Power Line Cycles (NPLC) or directly in seconds (Time). Only 1, 2, 10, 20, 100,
and 200 PLC provide normal mode (line frequency noise) rejection. Selecting 100 PLC provides the best
noise rejection and resolution, but the slowest measurements.
NPLC - Sets the integration time as 0.02, 0.06, 0.2, 1, 2, 10, 20, 100, and 200 Power Line Cycles
(PLC). Only 1 PLC and longer times provide normal mode (line frequency noise) rejection. Selecting 100
or 200 PLC provides the best noise rejection and resolution.
Time - Directly sets the integration time in seconds.
Advanced settings
Press Advanced to configure the advanced settings for the measurement.
Auto Zero - Autozero provides the most accurate measurements, but requires additional measurement
time to perform the zero measurement. With autozero enabled (On), the instrument internally measures
the offset following each measurement. It then subtracts that measurement from the preceding reading.
This prevents offset voltages present on the instrument’s input circuitry from affecting measurement accur-
acy. With autozero disabled (Off), the instrument measures the offset once and subtracts the offset from all
subsequent measurements. The instrument takes a new offset measurement each time you change the
function, range, or integration time. (There is no autozero setting for 4-wire measurements).
Reference - Thermocouple measurements require a reference junction temperature. You can input a
known fixed reference junction temperature (typically used for external reference junctions), use the intern-
ally measured temperature on the module as the reference junction temperature, or use the external ther-
mistor or RTD measurement. Selects the reference junction source as Internal, External, or Fixed.
Open Check - Enables (On) or disables (Off) the thermocouple check feature to verify that the ther-
mocouples are properly connected for measurements. When enabled, the instrument performs a res-
istance measurement with each temperature to check for an open circuit. If one is detected, the result will
be shown as +Overload. If this check is not performed, measurement of an open circuit can produce a
voltage reading near zero resulting in an invalid temperature reading.
Delay - Selects whether the delay between channels in the scan list will be automatically or manually selec-
ted. By selecting Auto, instrument will automatically determine the channel delay based on measurement
function, range, integration time, and AC filter setting. By selecting Time, the specified delay (time in
seconds) is inserted between the relay closure and the actual measurement on each channel, in addition to
any delay that will implicitly occur due to relay settling time.
2-wire and 4-wire thermistor
Keysight DAQ970A User's Guide 91
[Channel] Menu Overview
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