User`s guide

Remarks
Autozero ONCE issues an immediate zero measurement, and then sets
autozero to OFF.
The autozero mode is set indirectly when you set the resolution and
integration time using the CONfigure or MEASure commands. Autozero is
automatically turned off when you select an integration time less than 1
PLC with these commands.
The autozero mode is reset to the default (ON) at power up, or after a
Factory Reset (*RST command) or an Instrument Preset (SYSTem:PRESet
command).