Keithley 2002, User Manual, Page: 218 / 366

IEEE-488 Reference
3-95
:NPLCycles? Query programmed NPLC value
:NPLCycles? DEFault Query *RST default value
:NPLCycles? MINimum Query minimum NPLC value
:NPLCycles? MAXimum Query maximum NPLC value
The integration period (measurement speed) for the Model 2002 can be set using either of two
commands; :APERture (paragraph 3.18.5) or :NPLCycle. Aperture specifies time (in seconds)
per integration, while NPLC expresses the integration period by basing it on the power line fre-
quency. See paragraph 2.4 for details on integration (SPEED).
When the integration period is set using the :NPLCycles command, the time value for the
:APERture command changes accordingly to reflect the new integration rate. Conversely, if the
integration period is set using the :APERture command, the value for the :NPLCycle command
changes accordingly.
On power-up, the instrument uses the NPLC value to determine the integration period.
Note: If line synchronization is enabled (see:LSYNc command in SYSTem subsystem), the
integration period will 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 will not
start until that power line cycle is completed. The integration period starts when the positive-
going sine wave crosses zero volts. See paragraph 2.12.7 for more details.
PRINT #1, "output 16; :curr:ac:nplc 2; nplc?" ' Set NPLC for ACI
PRINT #1, "enter 16" ' Get response from 2002
:AUTO <b>|ONCE
[:SENSe[1]]:CURRent:AC:NPLCycles:AUTO <b>|ONCE Control auto NPLC for ACI
[:SENSe[1]]:CURRent:DC:NPLCycles:AUTO <b>|ONCE Control auto NPLC for DCI
[:SENSe[1]]:VOLTage:AC:NPLCycles:AUTO <b>|ONCE Control auto NPLC for ACV
[:SENSe[1]]:VOLTage:DC:NPLCycles:AUTO <b>|ONCE Control auto NPLC for DCV
[:SENSe[1]]:RESistance:NPLCycles:AUTO <b>|ONCE Control auto NPLC for
Ω
2
[:SENSe[1]]:FRESistance:NPLCycles:AUTO <b>|ONCE Control auto NPLC for
Ω
4
[:SENSe[1]]:TEMPerature:NPLCycles:AUTO <b>|ONCE Control auto NPLC for TEMP
<b> = 1 or ON Enable auto NPLC
0 or OFF Disable auto NPLC
ONCE Enable and then disable auto NPLC
:AUTO? Query state of auto NPLC
These commands are used to enable or disable auto NPLC for the specified measurement func-
tion. With auto NPLC enabled, the instrument automatically optimizes the NPLC value for the
present resolution setting. Tables 2-8, 2-13, 2-18 and 2-24 provide the integration times for SET-
BY-RSLN (AUTO).
The ONCE parameter is analogous to a momentary toggle switch. When :AUTO ONCE is sent,
auto NPLC turns on momentarily and then disables. While enabled, it automatically selects the
appropriate value as summarized in the tables. When auto NPLC disables, NPLC remains at the
selected value.
:NPLC:AUTO is coupled to the command that manually sets the NPLC value (:NPLC <n>).
When auto NPLC is enabled, the parameter value for :NPLC <n> changes to the automatically
selected NPLC value. Thus, when auto NPLC is disabled, NPLC remains at the automatically
Query
Description
Program fragment
Parameters
Query
Description