User`s guide

Features and Functions 3
Agilent 34980A Mainframe User’s Guide 87
Measurement Resolution
Resolution is expressed in number of digits the internal DMM can
measure or display on the front panel. You can set the resolution to 4, 5,
or 6 full digits, plus a “½” digit which can be “0” or “1”. To increase the
measurement accuracy and improve noise rejection, select 6½ digits.
To increase the measurement speed, select 4½ digits.
• For ac voltage measurements, the resolution is fixed at 6½ digits.
The only way to control the reading rate for ac measurements is by
changing the channel delay (see “Channel Delay” on page 120) or by
setting the ac filter to the highest frequency limit (see “AC Low
Frequency Filter” on page 102).
• The specified resolution is used for all measurements on the selected
channel. If you have applied Mx+B scaling, have assigned alarms to the
selected channel, or are in Monitor mode, those measurements are also
made using the specified resolution.
• Changing the number of digits does more than just change the
resolution of the instrument. It also changes integration time, which is
the measurement sampling period for the instrument’s A/D converter.
See “Custom A/D Integration Time” on page 88 for more information.
• The
CONFigure and MEASure? commands contain an optional parameter
which allows you to specify the resolution.
• The instrument returns to 5½ digits when the measurement function is
changed and after a Factory Reset (
*RST command). An Instrument
Preset (
SYSTem:PRESet command) or Card Reset (SYSTem:CPON
command) does not change the resolution setting.
Front Panel Operation: DMM or Channel (Configure) > INTEGRATION > NPLC
Select the measurement function on the active channel, then select the
desired resolution at the next menu level.
Remote Interface Operation: Specify the resolution in the same units as
the measurement function, not in number of digits. For example, if the
function is dc voltage, specify the resolution in volts. For frequency,
specify the resolution in hertz.
You can select the resolution using parameters in the
CONFigure and
MEASure? commands. For example, the following command selects the
10 Vdc range with 4½ digits of resolution on the specified channel.
CONF:VOLT:DC 10,0.001,(@3001)
The following command selects the 1A range with 6½ digits of resolution
on channel 2041 (current measurements are allowed only on channels 41
through 44 on the 34921A).
MEAS:CURR:AC? 1,1E-6,(@2041)
You can also select the resolution using the SENSe commands. For example,
the following command specifies a 2- wire ohms measurement with 100
 of
resolution on channel 1003.
SENS:RES:RES 100,(@1003)