User`s manual

Offset
Compensation
Anytime a resistance measurement is made, offset voltages internal and
external to the multimeter can be present. When these offsets are added to
the voltage induced (by the multimeter) across the resistance, measurement
accuracy is affected. Offset compensation cancels the offset voltage by:
1. Turning on the current source and measuring the induced voltage.
2. Turning off the current source and measuring the offset voltage.
3. Taking the difference between the induced and offset voltages and
dividing that number by the amount of current applied.
The result is the resistance measurement output from the multimeter.
Note The multimeter can compensate for offset voltages that are 10% of the
maximum voltage induced across the resistor.
When using offset compensation, consider the following:
1. Offset compensation allows you to make the most accurate 2-wire
and 4-wire resistance measurements; however, measurement speed is
decreased.
2. Offset compensation can be used on any measurement range;
however, on the highest range, the induced voltage is likely to be
much greater than the offset voltage. Thus, the offset voltage’s affect
on measurement accuracy is negligible.
3. The external circuit remains connected thus allowing an offset
measurement to be made for the SUM of BOTH internal and external
offsets.
4. With the external circuit connected, any induced voltage in your
external wiring is compensated for. Induced voltage in your external
wiring could be due to thermal heating, noise pickup, or other battery
effects (thermocouple junctions at wiring points, for example).
5. Offset compensation (
OCOM) overrides autozero; however, if both
are on, the reading rate reflects the autozero state.
100 Understanding the HP E1326B/E1411B Multimeter Chapter 4