Keithley 2450 Reference Manual page 683

Section 8: TSP command reference
asymptote
Details
Sweeps are only available when the source function is set to voltage or current.
When the sweep is started, the instrument sources a specific voltage or current value to the device under test
(DUT). A measurement is made for each point of the sweep.
When the sweep command is sent, it creates a trigger model. To run the sweep, initiate the trigger model.
The sweep continues until the source outputs the specified stop level. At this level, the instrument performs
another measurement and then stops the sweep.
When you specify a delay, a delay block is added to the sweep trigger model. This delay is added to any source
delay you may have set. For example, if you set 10 ms for the source delay and 25 ms for the delay in the for the
log sweep command, the actual delay is 35 ms.
The range type specifies the source range that is used for the sweep. You can select the following options:
• Best fixed: The instrument selects a single fixed source range that accommodates all the source levels
in the sweep. This avoids overshoots during sweeps.
• Auto: The instrument automatically goes to the most sensitive source range for each source level in the
sweep.
• Fixed: The source remains on the range that is set when the sweep is started. If a sweep point that
exceeds the capability of the source range, the source outputs the maximum level for that range.
The asymptote changes the inflection of the sweep curve and allows it to sweep through zero. You can use the
asymptote parameter to customize the inflection and offset of the source value curve. Setting this parameter to
zero provides a conventional logarithmic sweep. The asymptote value is the value that the curve has at either
positive or negative infinity, depending on the direction of the sweep. The asymptote value must not be equal to
or between the starting and ending values. It must be outside the range defined by the starting and ending
values.
Example
reset()
smu.source.func = smu.FUNC_DC_VOLTAGE
smu.source.range = 20
smu.measure.func = smu.FUNC_DC_CURRENT
smu.measure.range = 100e-6
smu.source.sweeplog("VoltLogSweep", 1, 10, 20, 1e-3,
1, smu.RANGE_FIXED)
trigger.model.initiate()
Also see
Sweep operation
trigger.model.initiate()
8-152
Model 2450 Interactive SourceMeter® Instrument Reference Manual
Default is 0
(on page 3-51)
(on page 8-187)
Reset the instrument to its defaults.
Set the source function to voltage.
Set the source range to 20 V.
Set the measure function to
current.
Set the current range to 100 µA.
Set up a log sweep that sweeps
from 1 to 10 volts in 20 steps with a
source delay of 1 ms, a sweep
count of 1, and a fixed source
range. Name the configuration list
that is created for this sweep
VoltLogSweep.
Start the sweep.
2450-901-01 Rev. B/September 2013