8: TSP command reference Model DMM7510 7½ Digit Graphical Sampling Multimeter
8-172 DMM7510-901-01 Rev. B / May 2015
dmm.measure.nplc
This command sets the time that the input signal is measured for the selected function.
Type TSP-Link accessible Affected by Where saved Default value
Attribute (RW) Yes
Restore configuration
Instrument reset
Power cycle
Measure configuration list
Configuration script
Measure configuration list
1
Usage
nplc = dmm.measure.nplc
dmm.measure.nplc = nplc
The number of power line cycles:
• 60 Hz: 0.0005 to 15
•
Functions
dmm.FUNC_DIGITIZE_CURRENT
dmm.FUNC_DIGITIZE_VOLTAGE
Details
This command sets the amount of time that the input signal is measured. The amount of time is
specified as the number of power line cycles (NPLCs). Each PLC for 60 Hz is 16.67 ms (1/60) and
each PLC for 50 Hz is 20 ms (1/50). For 60 Hz, if you set the NPLC to 0.1, the time is 1.667 ms.
The shortest amount of time results in the fastest reading rate, but increases the reading noise and
decreases the number of usable digits.
The longest amount of time provides the lowest reading noise and more usable digits, but has the
slowest reading rate.
Settings between the fastest and slowest number of PLCs are a compromise between speed and
noise.
If you change the PLCs, you may want to adjust the displayed digits to reflect the change in usable
digits.
The measurement time can also be set as an aperture time. Changing the NPLC value changes the
aperture time and changing the aperture time changes the NPLC value.
Example
dmm.measure.func = dmm.FUNC_DC_VOLTAGE
dmm.measure.nplc = 0.5
Sets the measurement time to 0.0083 (0.5/60)
seconds.
Also see
dmm.measure.aperture (on page 8-131)
dmm.measure.linesync (on page 8-166)
Using aperture or NPLCs to adjust speed and accuracy (on page 4-1)
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