Autocalibration; Auto Calibration; Running Autocalibration - Keithley 2461 Reference Manual

Model 2461 Interactive SourceMeter® Instrument Reference Manual

Autocalibration

Automatic calibration removes measurement errors that are caused by the performance drift on the
components used in the source-measure unit (SMU) digitizer as a result of temperature and time.
Autocalibration improves short-term accuracy of the Model 2461. However, you must still perform
regular full calibration with metrology equipment to maintain overall accuracy.
Autocalibration of the Model 2461 is not necessary unless you are using a digitizer function to make
readings.
To maintain accuracy, run autocalibration when the instrument temperature changes by more than
±5 °C or one week has elapsed since the last autocalibration. To check the temperature difference,
you can view the temperature change on the Calibration menu. You can also use remote commands
to retrieve the temperature difference.
The instrument regularly monitors the internal temperature. Temperature checking begins after the
warm-up time completes. If you are using digitize functions, periodically check the temperature drift
by using the front-panel calibration screen or use remote commands to check the autocalibration
temperature drift.
The autocalibration constants are stored through a power cycle. You do not need to run
autocalibration because power has been cycled.

Running autocalibration

After the instrument has completed its warm up period, you can run autocalibration as needed using
the front panel or over a remote interface. Autocalibration takes 10 seconds to run. During
autocalibration, you cannot use the instrument.
To prevent instrument damage, verify that no test voltages are connected to the input terminals when
performing auto calibration.
Do not cycle power during the autocalibration routine. Doing so could affect the accuracy of the
instrument.
To prepare for auto calibration:
1. Disable voltage sources on any test cables that are connected to the front-panel or rear-panel
terminals.
2. Place the Model 2461 in a temperature-stable location.
3. Turn on instrument power and allow the instrument to warm up for at least 60 minutes. When the
instrument has completed the warm-up period, start monitoring the temperature drift if using a
digitize function.
2461-901-01 A/November 2015
Section 3: Functions and features
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