Performing Offset Nulling

Offset nulling consists of measuring the corresponding zero reading in a measurement path and subtracting this value from subsequent samples. The way you connect the leads to obtain the zero reading depends upon the type of measurement you are taking.

To perform offset nulling, complete the following steps:
  1. Disconnect the DUT from the leads that are connected to the DMM.
  2. Obtain zero readings based on the measurement you are making:
    • If measuring DC voltage or resistance, short the input leads to obtain the corresponding zero reading.
    • If measuring DC current, leave the leads unconnected (open circuit) to obtain the corresponding zero reading.
    • If in a switching system, make the open-circuit or short-circuit measurement with channels dedicated as short or as an open.
    Note NI recommends using cables and switches with low thermal voltages and low-path resistance to minimize the offset introduced by the measurement path.
  3. Record the value of the measurement.
  4. Connect the leads to the DUT, and subtract the value measured in step 3 from all subsequent measurements.
The subtraction operation can be performed programmatically with the ADE or using offset nulling in InstrumentStudio.
Note For resistance measurements in the ranges ≤10 kΩ, you can enable offset compensated ohms, which removes offsets in the measurement path much better than offset nulling alone.