Percent; Percent Deviation; Selecting And Configuring Math; Configure Math Menu Structure - Keithley 2002 User Manual

Front Panel Operation

2.10.2 Percent

This operation lets you specify a target reading value. The
displayed reading will be expressed as a percentage of the
target value, often in scientific notation. The percentage cal-
culation is performed as follows:
Input Reading
Percent = --------------------------------- - x 100
As an example, consider the default target value for percent-
age calculations, where:
100% = +1.000000e+00
Therefore, on the 200µA range, a 100µA input would be
0.01% of the target value and a typical reading would be dis-
played as follows:
+1.0000e+04µAAC%
Range: 200 µAAC Coupling: AC
Note that the value is not 10000%, but 10000µ%, which
equals 0.01%. With the calculate multiple display selected,
as described in paragraph 3.10.5, the display would be:
+1.0000e+04µAAC%
Reading = +100.000
where the bottom line shows the reading (in the units and
multiplier prefix of the top line) before the percentage calcu-
lation is performed.

2.10.3 Percent deviation

The following math calculation provides the percent devia-
tion between the normal display reading and the currently
stored REL value for the selected function:
PD =
where: X is the normal display reading
Y is the REL value for the selected function
PD is the displayed result (percent deviation)
Percent Deviation is enabled through the CONFIGURE
MATH menu (see paragraph 2.10.4).
Note that Percent Deviation does not scale based on the m, k,
or M range factor. For example, 10% deviation on the 20k
range will be displayed as 10.00000. If the number is too
large for the allowed number of leading zeroes (for example
10 on the 2k range), the display will switch to 7-1/2 digit
scientific notation.
2-76
Target Value
X-Y
-------------- - x 100%
Y
2.10.4 Selecting and configuring math
The polynomial, percent or percent deviation calculation is
selected and configured from the CONFIGURE MATH
menu (see Table 2-37). The selected calculation is enabled
by pressing the MATH key. The Model 2002 then displays
the result of the calculation, using scientific notation where
necessary. Pressing MATH a second time disables the
calculation.

Table 2-37

CONFIGURE MATH menu structure

Menu item Description
None Select no calculation when MATH
key is pressed.
Polynomial Select polynomial calculation and
enter constants.
Percent Select percent calculation and enter
target (reference) value.
Percent deviation Select percent deviation calculation.
NONE
With this menu item, no math operation goes into effect
when the MATH key is pressed. The MATH annunciator
lights, but NONE is displayed on the top line.
POLYNOMIAL
This menu item selects the polynomial calculation and
allows you to program the polynomial constants. The "a2"
constant is displayed first. You can retain the displayed value
or key in a new value. In either case, press ENTER to display
the "a1" constant. Retain or change this constant and press
ENTER to display the "a0" constant. If you change the "a0"
constant, be sure to again press ENTER.
PERCENT
This menu item selects the percent calculation and lets you
specify the target value. If you key in a new target value, be
sure to press ENTER.
PERCENT DEVIATION
This menu item selects the percent deviation calculation and
returns the display to the normal measurement state.