Keysight Technologies 3458A Guide D'utilisation page 144

4 Making Measurements
Using Reading Memory
The multimeter stores readings in memory whenever readings are being taken
and reading memory is enabled. Reading memory has a FIFO (first-in-first-out)
mode and a LIFO (last-in-first-out) mode. In the FIFO mode, the first reading
stored is the first reading returned when you recall readings without specifying
reading numbers (implied read method which is discussed later in this chapter). If
you fill the reading memory in the FIFO mode, all stored readings remain intact
and new readings are not stored.
In the LIFO mode, the last reading stored is the first reading returned when you
recall readings without specifying reading numbers. If you fill reading memory in
the LIFO mode, the oldest readings are replaced by the newest readings. You
enable reading memory and specify the mode using the MEM command.
(Specifying a reading memory mode erases any previously stored readings.) For
example, to specify reading memory using the LIFO mode, send:
OUTPUT 722."MEM LIFO"
The multimeter is now enabled to store readings. After storing readings, you can
disable reading memory and leave all stored readings intact by sending:
OUTPUT 722;"MEM OFF"
Later, you can resume the previous mode to store additional readings without
clearing any stored readings by sending:
OUTPUT 722;"MEM CONT"
Memory formats
Readings can be stored in one of five formats: ASCII, single integer (SINT), double
integer (DINT), single real (SREAL), or double real (DREAL). The memory space
required for each format is:
ASCII - 16 bytes per reading
SINT - 2 bytes per reading
DINT - 4 bytes per reading
SREAL - 4 bytes per reading
DREAL - 8 bytes per reading
[1] The ASCII format is actually 15 bytes for the reading plus 1 byte per reading for a null character
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which is used to separate stored ASCII readings only.
[1]
Keysight 3458A User's Guide