Keithley 6220 Reference Manual page 115

Model 6220/6221 Reference Manual
1. SOUR:CURR:STAR<n>
SOUR:CURR:STOP <n>
SOUR:CURR:STEP <n>
Use these commands to set the start and stop currents for linear and logarithmic
staircase sweeps and to set the step current for linear staircase sweeps. Setting
the stop value more positive than the start value will result in a positive-going
sweep. Conversely, setting the stop value more negative than the start value will
result in a negative-going sweep. Setting the step current negative will also cre-
ate a negative-going sweep.
The STEP value is subject to the condition that the total number of points
calculated does not exceed the maximum number of points allowed in the
sweep. For example, even though 1e-13 is technically allowed, if STARt and
STOP are 0 and 100 mA, a STEP of 1e-13 will return an error.
2. SOUR:CURR:CENT <n>
SOUR:CURR:SPAN <n>
These commands give an alternate method of setting sweep parameters.
Note that the CENTer value will be checked against the start and stop values,
resulting in errors if out of that range. For those sweeps that are specified
using the CENTer and SPAN commands, the STARt point will be the lower
point, and the sweep will always run from low to high. You can sweep from
high value to low value only by using the STARt and STOP commands to set
the higher value as the STARt point.
For example, if the center current is 50mA and the span is 100mA, the sweep
will range from 0mA to 100mA.
3. SOUR:DEL <n>
This command allows you to set a time delay to allow the source value to set-
tle. This delay is used for all steps of linear and log sweeps, but it does not
apply for custom sweeps since they use individual values (see
4. SOUR:SWE:ARM
After being armed, the sweep will begin with the next appropriate trigger. If the
Differential Conductance or Delta Mode is presently armed, this command will
"un-arm" that sequence and arm a sweep. If either Differential Conductance
or Delta is already running, however, Error -221 Settings Conflict is returned.
When a sweep is armed, the two-second message SWEEP ARMED appears
on the display, and the ARM annunciator is turned on. When the sweep has
completed a finite count, the source is left on and zero is output. When the
sweep is aborted (by either the EXIT key or SOUR:SWE:ABORt), the source
is set to zero and turned off.
If the sweep spacing has been set to LOGarithmic, problems would occur
when calculating the sweep table when either the start or stop points equal
zero. In these cases, if the SOUR:SWE:STAR or SOUR:SWE:STOP value is
zero, it will be adjusted automatically to the smallest adjustable value,
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' Set start current
' Set stop current
' Set step current
' Set center current
' Set span current
' Set source delay for sweep
' Prepare (arm) sweep to run
Return to Section 4 topics
Sweeps 4-19
Table 4-5).