NI 4081

The NI 4081 DMM for the PXI Express bus has a 7½ digit capability for the resistance and DCV modes and a 6½ digit capability for all other modes. The NI 4081 has a 1000 V capability. For more information about the NI 4081 specifications, refer to Related Documentation for the NI 4081 specifications document.

Interconnects and Cables

The front of the NI 4081 module has four high-voltage, safety-agency approved banana plug connectors. For an illustration of the front panel connectors and wiring instructions, refer to the Front Panel Connections topic for the NI 4081.

For use with the NI 4081, NI recommends selecting a cable with characteristics similar to the Belden 83317E; refer to the Belden CDT Incorporated Web site at www.belden.com for information about this cable.

Tape-wrapped polytetrafluoroethylene (PTFE) insulation guarantees low leakage. Copper conductors with silver plating perform very well for low-voltage measurements because of their low thermal characteristics. Use a cable with at least 90% shielding effectiveness.

Operation

The NI 4081 can operate as a DMM and can acquire waveforms up to 1.8 MS/s. Refer to the NI PXIe-4081 Specifications document for the functions and ranges supported by the NI 4081.

The following table lists the functions and ranges supported by the NI 4081 while in DMM mode:

DMM Function Ranges
DC Voltage 100 mV, 1 V, 10 V, 100 V, 1000 V
AC Voltage 50 mV, 500 mV, 5 V, 50 V, 700 V
DC Current1 1 µA, 10 µA, 100 µA, 1 mA, 10 mA, 100 mA, 1 A, 3 A
AC Current1 100 µA, 1 mA, 10 mA, 100 mA, 1 A, 3 A
2-Wire Resistance 100 Ω, 1 kΩ, 10 kΩ, 100 kΩ, 1 MΩ, 10 MΩ, 100 MΩ, 5 GΩ
4-Wire Resistance 100 Ω, 1 kΩ, 10 kΩ, 100 kΩ, 1 MΩ, 10 MΩ
Diode 10 V at 1 µA / 10µA / 100µA; 4.0 V at 1 mA
Frequency/Period2 15 Hz - 500 kHz / 2 µs - 67 ms

1To measure current outside of the normal range on the NI 4081, you must use a current shunt module (CSM). Refer to the Measuring Current section for more information.

2Frequency/Period voltage ranges are the same as AC voltage ranges.

The following table lists the functions and ranges supported for waveform acquisitions:

Waveform Function Ranges Coupling
Voltage Waveform 100 mV, 1 V, 10 V, 100 V, 1000 V AC or DC
Current Waveform1 100 µA, 1 mA, 10 mA, 100 mA, 1 A, 3 A DC
1To measure current outside of the normal range on the NI 4081, you must use a current shunt module (CSM). Refer to the Measuring Current section for more information.

The following table lists the available NI 4081 input resistance selections. NI calibrates the NI 4081 for full accuracy with all input resistances shown.

DCV ACV Voltage Waveform
Range Input Resistance Range Input Resistance Range Input Resistance
100 mV 10 MΩ (default) or 10 GΩ 50 mV 10 MΩ 100 mV 10 GΩ or 10 MΩ (default)
1 V 10 MΩ (default) or 10 GΩ 500 mV 10 MΩ 1 V 10 GΩ or 10 MΩ (default)
10 V 10 MΩ (default) or 10 GΩ 5 V 10 MΩ 10 V 10 GΩ or 10 MΩ (default)
100 V 10 MΩ (default) 50 V 10 MΩ 100 V 10 MΩ (default)
1000 V 10 MΩ (default) 700 V 10 MΩ 1000 V 10 MΩ (default)

Additional Features

  • Self-Calibration
  • Auto Zero
  • Configuring Auto Range
  • Offset Compensated Ohms
  • ADC Calibration
  • Input Resistance
  • Configuring Measurement Timing
  • Aperture Time
  • DC Noise Rejection
  • Waveform Acquisitions
  • Single Point Acquisitions
  • Generating Measurement Complete
  • Scanning Switch Modules

Replacing the Fuse

The NI 4081 is equipped with a 3.5 A 1000 V time-delay user-replaceable fuse designed to help protect the DMM and your test system. For information on replacing the fuse, refer to the Fuse Replacement topic for the NI 4081.

Calibrating the NI 4081

Calibration maximizes the accuracy of a DMM. To ensure accuracy, you must perform calibration. NI recommends that you externally calibrate every two years. Refer to the self-calibration or ADC calibration sections to internally calibrate the NI 4081. Refer to the NI 4081 7½-Digit DMM Calibration Procedure at the NI Calibration Solutions Web site for information on externally calibrating the NI PXI-4081. For information on calibrating the NI 4081 using Calibration Executive, refer to the NI Calibration Solutions Web site. All NI measurement devices receive NIST-traceable calibration before shipping.