Keithley 6517B Reference Manual

Model 6517B Electrometer Reference Manual Section 14: SCPI command reference
6517B-901-01 Rev. C / August 2015 14-59
:APERture <n>
This command is used to set the aperture for volts, amps, ohms, and coulombs.
Usage
:APERture <n>
:APERture?
:APERture? DEFault
:APERture? MINimum
:APERture? MAXimum
<n>
 166.6666666667e-6 to 200e-3: Integration period in seconds
 DEFault: Power line cycle integration: 16.67 ms for 60Hz power line; 20 ms
for 50 Hz and 400 Hz power line
 MINimum: 166.6666666667e-6 s
 MAXimum: 200 ms
Example
The integration period (measurement speed) for the Model 6517B can be set using either of two
commands: NPLCycle or :APERture. The NPLC method specifies the integration period as the
number of power line cycles per integration, while aperture specifies the time (in seconds) per
integration. The relationship between NPLC and aperture is expressed as follows:
Aperture = NPLC
ƒ
Where:
 Aperture is the integration rate in seconds per integration.
 NPLC is the number of power line cycles per integration.
 ƒ is the power line frequency.
For 400 Hz line power, use 50 Hz to calculate aperture.
When the integration period is set using the :APERture command, the value for the :NPLCycle
command changes accordingly to reflect the new integration period. Conversely, if the integration
period is set using the :NPLCycle command, the value for the :APERture command changes
accordingly.
On power-up, the instrument uses the NPLC value to determine the integration period. Thus, if using
a different power line frequency, NPLC remains the same, but aperture may change.
If line synchronization is enabled (:LSYNc:STATe <b> (on page 14-124)), the integration period does
not start until the beginning of the next power line cycle. For example, if a reading is triggered at the
positive peak of a power line cycle, the integration period does start until that power line cycle is
completed. The integration period starts when the positive-going sine wave crosses zero volts.
Also see
:NPLCycles <n> (on page 14-61)

Keithley 6517B Specifications

General

Brand	Keithley
Model	6517B
Category	Measuring Instruments
Language	English