6482-901-01 Rev. A / August 2012
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4-3
Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
Section 4: Range, Digits, Speed, and Filters
Autorange limits
Upper and lower autorange limits are included to support the autorange change mode. The upper
limit must be greater than or equal to the lower limit, and the lower limit must be less than or equal
to the upper limit. If the lower limit is equal to the upper limit, autoranging is effectively disabled.
When autoranging is disabled, you can manually change to any range below the lower limit or any
range above the upper limit.
Setting autorange limits
To set the upper or lower autorange limit:
1. Press the
CONFIG
key.
2. To set the upper limit, press RANGE
key to select the ULIMIT prompt.
To set the lower limit, press RANGE
key to select the LLIMIT prompt.
3. At the prompt, use the RANGE
or
keys again to set the limit.
Autorange speed limitations
With autorange enabled, a minimum of two extra readings are required to move up range, and one
additional reading is needed to move down range. No additional readings are required if no range
change is required.
Autorange operation with range limits
The autorange limits are only evaluated when an autorange condition exists and forces the limits
to be re-evaluated. Only the upper limit is evaluated if the instrument needs to up-range; similarly,
only the lower limit is evaluated if the instrument needs to down-range. Both limits are not checked
simultaneously for any given autorange evaluation.
For example, if the instrument is on a higher manual range that is above the programmed upper
range limit and autorange is then enabled, the instrument will not re-evaluate the range limits until
a change in the input signal level forces a range change. In this example, the instrument would
stay on a range above the programmed upper limit with autorange enabled until the input signal
level changes accordingly.
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 both channels.
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.
Setting display resolution
There are two ways to set display resolution:
•
DIGITS
: Press the
DIGITS
key until the required resolution is displayed.
•
CONFIG DIGITS
: Press the
CONFIG
key and then the
DIGITS
key to display the digits
menu. Place the cursor to select the resolution (3.5, 4.5, 5.5, or 6.5) and press the
ENTER
key.
NOTE
The DIGITS setting affects only the single-channel display mode; it does not affect dual-
channel display. Changing SPEED changes DIGITS, but changing DIGITS does not
change SPEED.
Summary of Contents for 6482
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