User manual

IEEE-488 Reference
4-116 2001-900-01 Rev. K / August 2010
:curr:dc:aper:auto?
:volt:ac:aper:auto?
:volt:dc:aper:auto?
:res:aper:auto?
:fres:aper:auto?
:temp:aper:auto?
Response message:0 (off) or 1 (on)
These commands are used to enable or disable auto aperture for for the specified measurement
function. With auto aperture enabled, the instrument will automatically select the aperture value
to optimize the measurement.
When auto aperture is enabled for the TEMP function, the instrument will select an aperture val-
ue of 16.67msec for the 60Hz power line (20msec for the 50Hz or 400Hz power line). The ap-
erture values selected by the instrument for the other measurement functions are summarized in
Table 4-13 through Table 4-16.
The ONCE parameter is analogous to a momentary toggle switch. When :AUTO ONCE is sent,
auto aperture will turn on momentarily and then disable. While enabled it will automatically se-
lect the appropriate value as summarized in the tables. When auto aperture disables, the aperture
will remain at the selected value.
:APERture:AUTO is coupled to the command that manually sets the aperture value (:APERture
<n>). When auto aperture is enabled, the parameter value for :APERture <n> changes to the
automatically selected aperture value. Thus, when auto aperture is disabled, the aperture will
remain at the automatically selected value.
Auto aperture is also coupled to auto NPLC. Enabling or disabling auto aperture also enables
or disables auto NPLC. Also, a valid NPLC value sent using the :NPLC command will disable
auto aperture.
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Auto aperture; ACI
Resolution
Aperture value
(Auto aperture enabled)
6H digits*
5H digits*
4H digits*
Auto resolution enabled
166.67msec (60Hz power line cycle)
200msec (50Hz and 400Hz)
333.33µsec (60Hz)
400µsec (50Hz and 400Hz)
166.67µsec (60Hz)
200µsec (50Hz and 400Hz)
* Auto resolution disabled.