Keithley 2001 Operator's Manual page 278

IEEE-488 Reference
Programming example
Parameters
4-120
An alternate way to set the integration rate is by programming the aperture, which is seconds
per integration (see :APERture command). If the aperture is already known, the following equa-
tion can be used to determine the number of power line cycles per integration (NPLC):
NPLC = Aperture  f
where; NPLC is the number of power line cycles per integration.
Aperture is the integration period in seconds per integration.
f is the power line frequency (Note: For 400Hz line power, use 50Hz to calculate ap-
erture).
Keep in mind that when the integration period is set using the :NPLCycles command, the time
value for the :APERture command will change accordingly to reflect the new integration rate.
Conversely, if the integration period is set using the :APERture command, the value for the
:NPLCycle command will change accordingly.
On power-up, the instrument will use the NPLC value to determine the integration period. Thus,
if using a different power line frequency, the NPLC value will remain the same, but the aperture
time value may change.
Note: If line synchronization is enabled (see:LSYNc command in SYSTem subsystem), the in-
tegration 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
10 OUTPUT 716; ":curr:ac:nplc 2; nplc?"
20 ENTER 716; A$
30 PRINT A$
40 END
Line 10 Sets the integration rate for two cycles per measurement, and then queries the NPLC
value.
Line 20 Addresses the Model 2001 to talk.
Line 30 Displays the programmed NPLC value (2).
:AUTO <b>|ONCE
[:SENSe[1]]:CURRent:AC:NPLCycles:AUTO <b>|ONCEControl auto NPLC for ACI
[:SENSe[1]]:CURRent[:DC]:NPLCycles:AUTO <b>|ONCEControl auto NPLC for DCI
[:SENSe[1]]:VOLTage:AC:NPLCycles:AUTO <b>|ONCEControl auto NPLC for ACV
[:SENSe[1]]:VOLTage[:DC]:NPLCycles:AUTO <b>|ONCEControl auto NPLC for DCV
[:SENSe[1]]:RESistance:NPLCycles:AUTO <b>|ONCEControl auto NPLC for 2
[:SENSe[1]]:FRESistance:NPLCycles:AUTO <b>|ONCEControl auto NPLC for 4
[:SENSe[1]]:TEMPerature:NPLCycles:AUTO <b>|ONCEControl auto NPLC for TEMP
<b> = 1 or ON
= 0 or OFF
ONCE
paragraph 3.12
Enable auto NPLC
Disable auto NPLC
Enable and then disable auto NPLC
for more details.
2001-900-01 Rev. K / August 2010