Ranges; Source Range - Keithley 2450 Reference Manual

Model 2450 Interactive SourceMeter® Instrument Reference Manual
Using SCPI commands:
To set the limit when sourcing current, send the command:
SOURCe:CURRent:PROTection <n>
Where <n> is the current limit value. To set for a voltage measurement, replace CURRent with
VOLTage.
Using TSP commands:
To set the limit when sourcing current, send the commands:
smu.source.func = smu.FUNC_DC_CURRENT
smu.source.vlimit.level = limitValue
To set the limit when sourcing voltage, send the commands:
smu.source.func = smu.FUNC_DC_VOLTAGE
smu.source.ilimit.level = limitValue
Where limitValue is the limit value.

Ranges

You can set ranges for the source and measurement values. You can set specific ranges or allow the
instrument to choose the ranges automatically.
The source range determines how accurately the source output can be set.
The measurement range determines the full-scale input for the measurement. The measurement
range also affects the accuracy of the measurements and the maximum signal that can be measured.
The highest available range is determined by the limit setting for the function that is being sourced or
measured.

Source range

For most applications, you will select the automatic source range. This causes the instrument to set
the source range to the best range for the present settings.
In most cases, the only reason you would select a specific source range is to reduce the time that is
needed to make a measurement. Selecting a specific range eliminates the time that the instrument
needs to select the range automatically.
If you set the source range manually through either the front panel or a remote command, the setting
for automatic source range is set to disabled.
The selected source range must be within the limit set by the overvoltage protection limit. When the
overvoltage protection level is exceeded, OVP is displayed in the SOURCE area of the Home screen.
To select the range, specify the approximate source value that you will use. The instrument selects
the lowest range that can accommodate that level. For example, if you expect to source levels around
3 V, send the command set to 0.05 (or 50e-3) to select the 200 mV range.
2450-901-01 Rev. B/September 2013
Section 2: General operation
2-101