Rel; Front Panel Rel - Keithley 2601 Reference Manual

Section 6: Range, Digits, Speed, Rel, and Filters

Rel

The rel (relative) feature can be used to null offsets or subtract a baseline reading from present
and future readings. With REL enabled, subsequent readings will be the difference between the
actual input value and the rel value as follows:
Displayed Reading = Actual Input - Rel Value
Once a rel value is established for a measurement function, the value is the same for all ranges.
For example, if 0.5A is set as a rel value on the 1A range, the rel value is also 0.5A on the lower
current ranges.
Selecting a range that cannot accommodate the rel value does not cause an overflow condition,
but it also does not increase the maximum allowable input for that range. For example, on 1A
range, the SourceMeter still overflows for a >1.02A input.
NOTE When rel is enabled, the REL annunciator turns on. Changing

Front panel rel

Enabling and disabling rel
Rel can be used to null out zero offsets or to establish a zero baseline by pressing the REL key.
The reading (which becomes the rel value) is subtracted from itself. As a result, a zero reading is
displayed. Pressing REL a second time disables rel.
Defining a rel value
A unique rel value can be established for the selected measurement function from the front panel
as follows:
1. Press CONFIG then REL.
2. Choose the measurement function (CURRENT, VOLTAGE, OHMS, or WATTS), then press
ENTER or the Rotary Knob.
3. The present rel value will be displayed.
4. Set the desired rel value.
5. With the desired rel value displayed, press ENTER or the Rotary Knob, and then use EXIT
to back out of the menu structure.
6-8
measurement functions disables rel.
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Series 2600 System SourceMeter® Instruments Reference Manual
2600S-901-01 Rev. C / January 2008