Keithley 2651A Reference Manual page 45

Model 2651A High Power System SourceMeter® Instrument Reference Manual
This extra time can cause problems in sweeps and other test sequences in which measurement
timing is critical. To avoid the extra time for the reference measurements in these situations, the OFF
selection can be used to disable the automatic reference measurements. Note that with automatic
reference measurements disabled, the instrument may gradually drift out of specification.
To minimize the drift, a reference and zero measurement should be made just prior to the critical test
sequence. The ONCE setting can be used to force a refresh of the reference and zero measurements
used for the current aperture setting.
Autozero settings
Autozero setting
OFF
ONCE
AUTO
Front-panel autozero
Set the autozero from the front panel as follows:
1. Press the CONFIG key, and then press the MEAS key.
2. Turn the navigation wheel
navigation wheel
3. Turn the navigation wheel
the ENTER key or the navigation wheel
4. Press the EXIT (LOCAL) key to return to the normal display.
Remote command autozero
Use the autozero command with the appropriate option shown in the following table to set autozero
through a remote (see
the following command to activate channel A automatic reference measurements:
smua.measure.autozero = smua.AUTOZERO_AUTO
Autozero command and options
Command
smua.measure.autozero = smua.AUTOZERO_OFF
smua.measure.autozero = smua.AUTOZERO_ONCE
smua.measure.autozero = smua.AUTOZERO_AUTO
**Old NPLC cache values will be used when autozero is disabled (see
2651A-901-01 Rev. A / March 2011
Description
Turns automatic reference measurements off.
Turns automatic reference measurements off, but immediately taking one
reference and one zero measurement.
Automatically takes new acquisitions when processor determines
reference and zero values are out-of-date.
to select AUTO-ZERO, and then press the ENTER key or the
.
to select the desired mode (OFF, ONCE, or AUTO), and then press
smuX.measure.autozero
.
(on page 7-192) for more details). For example, send
Description
Disable autozero**
Force one ref and zero
Reacquire ref and zero with
measurement when needed
NPLC caching (on page 2-24)).
Section 2: General operation
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