User`s guide

Remarks
The FETCh? command will wait until the measurement is complete to
terminate.
The 34410A provides volatile reading memory for up to 50,000 readings.
The 34411A/L4411A provides volatile reading memory for up to 1,000,000
readings. If memory overflows, a status register bit is set and new
readings will overwrite the first (oldest) readings stored. The most recent
readings are always preserved.
You can use the R? command to obtain whatever readings are present
(with no wait), but the readings will be erased as you read them. The
DATA commands allow you to access a specific reading.
The instrument clears all readings from volatile memory after a Factory
Reset (*RST command), after an Instrument Preset (SYSTem:PRESet
command), when mainframe power is cycled, when the configuration is
changed (see CONFigure), or on an INITiate command.