Figure - Keithley SourceMeter 2400 User Manual

®
2400 Series SourceMeter User's Manual
Speed
The Speed/Accuracy menu is used to set the integration time of the A/D converter (period
of time the input signal is measured). The integration time affects the usable digits, the
amount of reading noise, and the ultimate reading rate of the instrument. The integration
time is specified in parameters based on the number of power line cycles (NPLC), where 1
PLC for 60Hz is 16.67msec (1/60) and 1 PLC for 50Hz and 400Hz is 20msec (1/50).
In general, the fastest integration time (FAST; 0.01 PLC) results in increased reading noise
and fewer usable digits. The slowest integration time (HI ACCURACY; 10 PLC) provides
the best noise rejection. In-between settings are a compromise between speed and noise.
The default power-on speed setting is NORMAL (1 PLC).
NOTE For the Pulse Mode of the Model 2430, the valid NPLC range is 0.01 to 0.1
PLC.
The speed setting affects both the NMRR (normal mode rejection ratio) and
CMRR (common mode rejection ratio). Normal mode noise is the noise signal
between the HI and LO input terminals, while common mode noise is the noise
signal between LO and chassis ground. See
specifications.
Setting speed
Speed is set from the Speed Accuracy menu and is structured as follows. Use
"Rules to navigate
NOTE For the Pulse Mode of the Model 2430, speed is set from Pulse Speed menu. This
menu structure is located after the Speed Accuracy menu. Use the
igate menus" in
Front panel speed control
Press SPEED or CONFIG SPEED to display the menu. (See
• FAST — Sets speed to 0.01 PLC and sets display resolution to 3
• MED — Sets speed to 0.10 PLC and sets display resolution to 4
• NORMAL — Sets speed to 1.00 PLC and sets display resolution to 5
• HI ACCURACY — Sets speed to 10.00 PLC and sets display resolution to 6
digits.
• OTHER — Use to set speed to any PLC value from 0.01 to 10. Display resolution
is not changed when speed is set with this option.
NOTE After setting speed, display resolution can be changed using the DIGITS key.
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Range, Digits, Speed, and Filters
Appendix A
menus," to check and/or change the speed setting.
Section 1 to check and/or change the speed setting.
7-7
for NMRR and CMRR
Section 1,
"Rules to nav-

Figure

7-1.)
digits.
digits.
digits.