DMM Measurement Defaults
The following table lists the default measurement settings for the NI 4065.
| Function | Aperture | DC Noise Rejection |
|---|---|---|
| DC 6½ digits | 200 ms | Second-Order |
| DC 5½ digits | 3.33 ms | Normal |
| DC 4½ digits | 333 µs | Normal |
| DC Auto Range | 3.33 ms | Normal |
| AC |
| Second-Order |
| AC Auto Range | Max (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 kΩ | 10 ms |
| Resistance 10 kΩ | 40 ms |
| Resistance 100 kΩ | 200 ms |
| Resistance 1 MΩ | 200 ms |
| Resistance ≥ 10 MΩ | 750 ms |
| AC V AC coupled | 1.5 secs |
| DC I | 10 ms |
| AC I | 1.5 secs |
| Diode | 40 ms |
To adjust the default settling times, refer to Configuring Measurement Timing.