
Model 2450 Interactive SourceMeter® Instrument Reference Manual
Section 4: Source-measure considerations
2450-901-01 Rev. B/September 2013
4-9
The speed setting affects the normal mode rejection ratio (NMRR) and common mode rejection ratio
(CMRR). Normal mode noise is the noise signal between the HI and LO terminals; common-mode
noise is the noise signal between LO and chassis ground. See the Model 2450 specification for
NMRR and CMRR values at different PLC settings.
After adjusting the speed, you might want to adjust the number of digits that are displayed for
measurements. See
Setting the number of displayed digits
(on page 2-37).
To set NPLC using the front panel:
1. Press the
FUNCTION
key.
2. Select the source and measurement combination.
3. From the Home page, swipe to display the SETTINGS screen.
4. Next to NPLCs, select the number. The number pad dialog box is displayed.
5. Enter the value.
6. Select
OK
.
You can also set the speed by pressing the
MENU
key. Under Measure, select
Settings
, and then
select the value next to NPLCs.
Using SCPI commands:
To set the number of PLCs for current measurements, send the command:
:SENSe:CURRent:NPLCycles <n>
To set the number of PLCs for resistance measurements, send the command:
:SENSe:RESistance:NPLCycles <n>
To set NPLCs for voltage measurements, send the command:
:SENSe:VOLTage:NPLCycles <n>
Where
<n>
is a value from 0.01 to 10, with 0.01 resulting in the fastest reading rates and 10 resulting
in the lowest reading noise.
For example, to set NPLC for resistance measurements to 0.5, send the command
RES:NPLC 0.5
Using TSP commands:
To set NPLC, send the command
smu.measure.nplc
. For example, to set the NPLC value to 0.5
for voltage measurements, send the commands:
smu.measure.func = smu.FUNC_DC_VOLTAGE
smu.measure.nplc = 0.5
To assign a different measurement function, replace
smu.FUNC_DC_VOLTAGE
with one of the
following:
•
For current measurements:
smu.FUNC_DC_CURRENT
•
For resistance measurements:
smu.FUNC_RESISTANCE