Keithley 2461, Reference Manual, Page: 154 / 1109

Model 2461 Interactive SourceMeter® Instrument Reference Manual Section 2: General operation
2461-901-01 A/November 2015 2-127
Selecting a specific measure range
You need to set the measure function before you can set the measure range.
When selecting a measure range, to ensure the best accuracy and resolution, use the lowest range
possible that does not cause an overflow event.
If you set the measure range to a specific value, the setting for automatic measure range is set to
disabled.
From the front panel:
1. Press
FUNCTION
and select the measure function.
2. On the Home screen, select the button next to Range in the measurement view area. The Range
dialog box is displayed.
3. Select the range. The selected value is displayed.
If the instrument displays an overflow message, select a higher range.
Over a remote interface:
•
SCPI commands: Refer to [:SENSe[1]]:<function>:RANGe[:UPPer] (on page 6-65).
•
TSP commands: Refer to smu.measure.range (on page 8-166).
Selecting the automatic measurement range
If you are using digitize functions, you cannot use the autorange feature.
When automatic measure range is selected, the instrument automatically selects the best range to
measure the signal. If the measurement reaches 105 percent of the present range, the instrument
changes the measurement range to the next higher range.
If you enable the automatic measurement range, the measurement range is changed when a
measurement is made. To read the measurement range that the instrument chose, you must query
the range after a measurement is made.
If you set low or high limits for the measurement when the automatic range is disabled, the limits are
not used until the limit is changed. The instrument only checks the upper limit when the limit is
increased. If the instrument is on a higher range than the present upper limit, and the instrument
automatically goes down a measurement range, it can still be on a range that is higher than the upper
limit. The opposite is true for the lower limit.
The instrument does not evaluate the limits until the instrument automatically changes the range. This
means that if the instrument is on a range that is above or below the upper or lower limits when the
automatic range is enabled or when the limit is set, no range change will occur until the range needs
to be changed.