Keysight Technologies 3458A Guide D'utilisation page 238

6 Command Reference
APER
Aperture. Specifies the A/D converter integration time in seconds.
Syntax
APER [aperture]
aperture
Specifies the A/D converter's integration time and overrides any previously
specified integration time or resolution. The valid range for aperture is 0 - 1 s in
increments of 100 ns. (Specifying a value <500 ns selects minimum aperture
which is 500 ns.)
Power-on aperture = is determined by the power-on value for NPLC which
specifies an integration time of 166.667 ms for a 60 Hz power line frequency, or
200 ms for a power line frequency of 50 Hz or 400 Hz.
Default aperture = 500 ns.
Remarks
– Since the APER and NPLC commands both set the integration time, executing
– Query command: The APER? query command returns the currently specified
– Related commands: FUNC, NPLC, RANGE, RES
238
either will cancel the integration time previously established by the other. The
RES command or the %_resolution parameter of a function or RANGE
command can also be used to indirectly select an integration time. An
interaction occurs between APER (or NPLC) when you specify resolution as
follows:
If you send the APER (or NPLC) command before specifying resolution, the
multimeter satisfies the command that specifies greater resolution (more
integration time).
If you send the APER (or NPLC) command after specifying resolution, the
multimeter uses the integration time specified by the APER (or NPLC)
command, and any previously specified resolution is ignored.
integration time (in seconds) used by the A/D converter. The integration time
may have been specified by the APER, NPLC, or RES command or by the
%_resolution parameter of a function command or the RANGE command.
Refer to Query commands near the front of this chapter for more information.
Keysight 3458A User's Guide