Section 3: Functions and features
Model DMM7510 7½ Digit Graphical Sampling Multimeter Reference Manual
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DMM7510-901-01 Rev. B / May 2015
Auto calibration
Automatic calibration removes measurement errors that are caused by the performance drift on the
components used in the DMM as a result of temperature and time. Auto calibration improves short-
term accuracy of the Model DMM7510. However, you must still perform regular full calibration with
metrology equipment to maintain overall accuracy.
To maintain accuracy, run auto calibration when the instrument temperature changes by more than
±5 °C since the last auto calibration. 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 for the voltage, current, 2-wire resistance,
4-wire resistance, diode, temperature, and DC voltage ratio function when autozero is enabled.
Temperature checking begins after the warm-up time completes. If there is a more than ±5 °C
difference between this temperature and the temperature when the last auto calibration was run, the
instrument generates an event in the event log and a warning message.
The auto calibration constants are stored through a power cycle. You do not need to run auto
calibration because power has been cycled.
You can run auto calibration with input cables connected. At the start of the auto calibration process,
the front terminals are monitored. If more than 30 V DC or 1 V AC is detected on the front-panel
inputs, auto calibration is not run and an event message is displayed.
Auto calibration also monitors the temperature at the start and end of auto calibration. If the start and
end temperature differs by more than ±1 °C, the auto calibration values are not stored and a warning
message is generated.
Running auto calibration
You can run auto calibration as needed by using the front panel or remote command. If the
instrument has completed the warm up period, auto calibration takes about six minutes to run. During
auto calibration, you cannot use the instrument. A status message is displayed on the front panel of
the instrument while auto calibration is running. At completion, a status message is generated.
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 auto calibration 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 DMM7510 in a temperature-stable location.
3. Turn on instrument power and allow the instrument to warm up for at least 90 minutes. When the
instrument has completed the warm-up period, a message is displayed and an information event
is generated in the event log.
