Keithley 2461, Справочное руководство, Страница: 156 / 1109

Model 2461 Interactive SourceMeter® Instrument Reference Manual Section 2: General operation
2461-901-01 A/November 2015 2-129
Automatic reference measurements
To ensure the accuracy of readings, the instrument must periodically get new measurements of its
internal ground and voltage reference. The time interval between updates to these reference
measurements is determined by the integration aperture that is being used for measurements. The
Model 2461 uses separate reference and zero measurements for each aperture.
By default, the instrument automatically checks the reference measurements whenever a signal
measurement is made. If the reference measurements have expired when a signal measurement is
made, the instrument automatically makes two more readings, one for the internal ground and one for
the voltage reference, before returning the result. This can cause some measurements to take longer
than normal.
This additional time can cause problems in sweeps and other test sequences in which measurement
timing is critical. To avoid the time that is needed for the reference measurements, you can disable
the automatic reference measurements.
When automatic reference measurements are turned off, the instrument may gradually drift out of
specification. To prevent inaccurate readings, you can use autozero once to update the autozero
information.
Setting autozero
You can enable or disable automatic referencing, or request a one-time refresh of the reference
values.
The reference setting is stored with the selected measure function.
To set autozero using the front panel:
1. Press the
FUNCTION
key.
2. Select the source and measure combination.
3. Press the
MENU
key.
4. Under Measure, select
Settings
.
5. For Auto Zero, select
On
or
Off
.
6. If Off is selected, you can select the
Zero Once
option to send a one-time refresh.
7. Select
HOME
to return to the operating display.
To set autozero using SCPI commands:
Refer to the following commands:
•
[:SENSe[1]]:<function>:AZERo[:STATe] (on page 6-57)
•
[:SENSe[1]]:AZERo:ONCE (on page 6-72)
To set autozero using TSP commands:
Refer to the following commands:
•
smu.measure.autozero.enable (on page 8-134)
•
smu.measure.autozero.once() (on page 8-135)