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6-6
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2600AS-901-01 Rev. B / September 2008
Section 6: Range, Digits, Speed, Rel, and Filters
Series 2600A System SourceMeter® Instruments Reference Manual
Digits
The display resolution of the measured reading depends on the DIGITS setting. This setting is
global, which means the digits setting selects display resolution for all measurement functions.
The DIGITS setting has no effect on the remote reading format. The number of displayed digits
does not affect accuracy or speed. Those parameters are controlled by the SPEED setting (see
Setting display resolution
To set display resolution, press the
DIGITS
key until the desired number of digits is displayed. The
display resolution will cycle through 4.5, 5.5, and 6.5 digits.
NOTE For the Model 2602A/2612A/2636A dual-channel display mode, the
maximum display resolution is 4.5 digits. For the Model 2602A/
2612A/2636A single-channel display mode, pressing the DIGITS key
for the channel not being displayed will have no effect, but the unit
will display a message advising you to change to the indicated
channel.
Remote digits programming
Digits commands
summarizes digits commands. See
for more information.
Digits programming example
--Select 5.5 digits.
display.smua.digits = display.DIGITS_5_5
Speed
The
SPEED
key is used to set the integration time, or measurement aperture, 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 16.67ms (1/60) and 1 PLC for 50Hz is 20ms (1/50).
In general, the fastest integration time (0.001 PLC) results in the fastest reading rate, but at the
expense of increased reading noise and fewer usable digits. The slowest integration time (25 PLC)
Table 6-3
Digits commands
Command
1
Description
display.smuX.digits = display.DIGITS_4_5
display.smuX.digits = display.DIGITS_5_5
display.smuX.digits = display.DIGITS_6_5
Set display to 4.5 digits.
Set display to 5.5 digits.
Set display to 6.5 digits.
1
smuX = smua for the Model 2601A/2611A/2635A; smuX = smua (Channel A) or smub (Channel B) for the
Model 2602A/2612A/2636A.