Fluke 8588A Operator's Manual page 37

The pole or time constant of the filter is formed by a 22 nF capacitor
across the resistance under test.
The selected range and resolution are remembered across Normal,
Tru ohm, and HV modes. For example, if Auto and 8 Digits are set in
2W Normal, they are also set in 4W Normal. If 4W Tru ohm is set to
the 100 ohm range and 7 digits, this does not affect the 2W and 4W
Normal Range and Resolution settings. The same is true for 2W and
4W HV ohms modes, they have their own range and resolution
settings.
LoI can be set individually for 2W Normal, 4W Normal, and 4W Tru,
and is remembered across these modes.
The Aperture setting (under Measure Setup) holds true for all of the
ohms modes, so once set, it used for all of the modes.
The Filter ON setting applies to the specific mode it was turned ON
in. and can be individually set for any of the modes, except 4W Tru
which does not allow Filter ON.
Resistance Modes
In the Ohms menu, when  (Mode) is pushed, different modes for making
resistance measurements are presented:
• 2W Normal Ω : This is the default setting and uses stimulus currents that
balance minimal self-heating of the resistance being measured with low
reading noise. 10 ranges are available, 1 Ω to 1 GΩ. 2-wire measurements
are made in this mode. The range and current used for that range are shown
in the information portion of the display. See Table 9 for the current stimulus
used based on the Product ohms range.
•
4W Normal: This setting is the same as 2W Normal except the
measurements are made using the 4-Wire measurement method.
• 4W Tru Ω : Using the 4-Wire measurement method, this mode uses a Tru
Ohms configuration and makes two measurements per reading, where the
second measurement is made with the current reversed relative to the first
measurement. The two measurements are combined to eliminate the effects
of any external EMFs that may be present. This mode provides 4-wire
measurements of resistance, in decade ranges from 1 Ω to 10 kΩ, and Auto
Ranging. The stimulus current is fed through the test resistance from the
Product's INPUT HI and LO terminals, and the resulting potential difference is
sensed by the SENSE HI and LO terminals. The range and current used for
that range are shown in the information portion of the display. See Table 9 for
the current stimulus used based on the Product ohms range.
Reference Multimeter and 8 ½ Digit Multimeter
Note
Note
Functions
33