Keithley 3700 series, Reference Manual, Page: 81 / 434

Series 3700 System Switch/Multimeter Reference Manual Section 4 : Range, Digits, Rate, Bandwidth, and Filter
Document Number: 3700S-901-01 Rev. A / August 2007 4-5
The front panel RATE settings for all but the AC functions are explained as follows:

FAST sets integration time to 0.1 PLC. Use FAST if speed is of primary importance (at
the expense of increased reading noise and fewer usable digits).

MEDium sets integration time to 1 PLC. Use MEDium when a compromise between
noise performance and speed is acceptable.

SLOW sets integration time to 5 PLC. SLOW provides better noise performance at the
expense of speed.
For the AC functions (ACV, ACV dB, and ACI), the RATE key sets integration time and
bandwidth. As listed in the following table, FAST sets NPLC to 1, while the MEDium and SLOW
NPLC settings are ignored.
Function Slow Medium Fast
DCV, DCI NPLC=5 NPLC=1 NPLC=0.1
ACV, ACI NPLC=X, BW=3 NPLC=X, BW=30 NPLC=1, BW=300
Ω2, Ω4, CSΩ
NPLC=5 NPLC=1 NPLC=0.1
FREQ, PERIOD APER=0.250s APER=0.1s APER=0.01s
Continuity X X NPLC=0.06
NOTES:
NPLC = Number of power line cycles.
BW = Bandwidth (in Hz).
APER = Aperture in seconds.
X = Setting ignored (fixed NPLC).
You can use unique rate settings for each function when using the front panel or the remote
interface.
NOTE Rate cannot be set for continuity; it is fixed at 0.006PLC.
Setting Rate from the front panel
The RATE key is used to set measurement speed from the front panel. Simply press the RATE
key until the desired speed message is displayed. The second line of the display will contain the
NPLC setting. Or, use the NPLC option under the function attribute menu (press
CONFIG -
DMM keys to display).
NOTE The Series 3700 uses internal references to calculate an accurate and stable reading.
When the NPLC setting is changed, each reference must be updated to the new
NPLC setting before a reading is generated. Therefore, frequent NPLC setting
changes can result in slower measurement speed.
Setting measurement speed over the bus
Use the dmm.aperture (on page 9-70) or dmm.nplc (on page 9-105) command to set the
measurement speed (integration time) over the bus.