3
Features and Functions
140
Keysight 34980A Mainframe User’s Guide
Voltage Measurement Configuration
This section contains information to help you configure the instrument for making
voltage measurements. The instrument can measure dc and true RMS ac-coupled
voltages on the measurement ranges shown below.
DC Input Resistance
Normally, the instrument’s input resistance is fixed at 10 M
Ω
for all dc voltage
ranges to minimize noise pickup. To reduce the effects of measurement loading
errors, you can set the input resistance to greater than 10 G
Ω
for the 100 mVdc,
1 Vdc, and 10 Vdc ranges.
Applies to dc voltage measurements only.
DC Input Resistance Settings for Voltage Measurements:
– The
CONFigure
and
MEASure?
commands automatically select AUTO OFF (fixed
at 10 M
Ω
for all ranges).
– The instrument selects 10 M
Ω
(fixed input resistance on all dc voltage ranges)
after a Factory Reset (
*RST
command). An Instrument Preset (
SYSTem:PRESet
command) or Card Reset (
SYSTem:CPON
command) does
not
change the input
resistance setting.
Front Panel Operation:
DMM or Channel (Configure) > INPUT RESISTANCE
Remote Interface Operation:
You can enable or disable the automatic input
resistance mode on the specified channels or the internal DMM. With AUTO OFF
(default), the input resistance is fixed at 10 M
Ω
for all ranges. With AUTO ON,
the input resistance is set to >10 G
Ω
for the three lowest dc voltage ranges.
[SENSe:]<
function
>:IMPedance:AUTO {OFF|ON} [,(@<
ch_list
>)]
100 mV
1 V
10 V
100 V
300 V
Autorange
Input Resistance Setting
Input Resistance for:
100 mV, 1 V, 10 V ranges
Input Resistance for:
100 V, 300 V ranges
Input Resistance: Auto OFF
Input Resistance: Auto ON
10 M
Ω
> 10 G
Ω
10 M
Ω
10 M
Ω