
Section 2: General operation
Model 2450 Interactive SourceMeter® Instrument Reference Manual
2-106
2450-901-01 Rev. B/September 2013
Selecting the automatic measurement range
When automatic measurement range is selected, the instrument automatically selects the best range
to measure the signal. If the measurement reaches 105% 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 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.
You need to set the measurement function before the measurement range can be set.
If you set the measurement range manually for a function, automatic measurement range is
automatically turned off for that function and remains off until you re-enable it.
Choose automatic measurement range using the front panel
Using the front panel:
1. Press
FUNCTION
and select the source and measurement function.
2. On the Home page, select the button next to Range. The Select Range dialog box is displayed.
3. Select
AUTO
. The Home page is displayed again with the selected value shown as AUTO.
Using SCPI commands
For the current range, send the command:
SENSe:CURRent:RANGe:AUTO ON
To set for a voltage measurement, replace
CURRent
with
VOLTage
.
To set for a resistance measurement, replace
CURRent
with
RESistance
.
Using TSP commands
To set automatic range for the current measurement function, send the commands:
smu.measure.func = smu.FUNC_DC_CURRENT
smu.measure.autorange = smu.ON
To set automatic range for the voltage measurement function, send the commands:
smu.measure.func = smu.FUNC_DC_VOLTAGE
smu.measure.autorange = smu.ON
To set automatic range for the resistance measurement function, send the commands:
smu.measure.func = smu.FUNC_RESISTANCE
smu.measure.autorange = smu.AUTORANGE_ON