DMM Measurement Defaults

NI Digital Multimeters

DMM Measurement Defaults

The following table lists the default measurement settings for the NI 4065.


FunctionApertureDC Noise Rejection
DC 6½ digits 200 msSecond-Order
DC 5½ digits 3.33 msNormal
DC 4½ digits 333 µsNormal
DC Auto Range3.33 msNormal
AC
  • AC 6½ digits — 1 sec
  • AC 5½ digits — Max (100 msec or (10/(minFreq)))
  • AC 4½ digits — Max (10 msec or (5/(minFreq)))
Second-Order
AC Auto RangeMax (100 ms or 10/(minFreq))Second-Order

By default, the Aperture time and DC Noise Rejection settings for a measurement are chosen by the driver based on the configured measurement and resolution. These values are chosen to ensure accuracy for 6½–digit measurements while not sacrificing performance at lower resolutions. For more information on a particular attribute, including how to configure a non-default setting, refer to Features. For AC, 5.5 digits, the aperture is expressed as Max (AC or 10/minFreq). minFreq, or minimum frequency, is a user–programmable parameter with a default value of 20 Hz.

The same applies for other user selectable values of minFreq. For example, for a minimum frequency of 50 Hz with a 5½ digit resolution, an aperture time of 10x the period of the 50 Hz signal is required, or in this example, 200 ms.

To adjust the default aperture time, refer to Configuring Measurement Timing.

Default Settling Times

Function Settling Time
DC (100 mV–10 V, 100 V, 300 V)10 ms
Resistance ≤1 kΩ10 ms
Resistance 10 kΩ40 ms
Resistance 100 kΩ200 ms
Resistance 1 MΩ200 ms
Resistance ≥ 10 MΩ 750 ms
AC V AC coupled1.5 secs
DC I10 ms
AC I1.5 secs
Diode40 ms

To adjust the default settling times, refer to Configuring Measurement Timing.