%Error; Scale; Pass/Fail (Limit Test); Null - HP 3456A Operating And Service Manual

Operation
(read Paragraph 3-56). Figure 3-8, the Numbered
Keyboard figure may also be helpful for the following
discussion of the math operation. They are:
OJoError

Scale

Pass/Fail (Limit Test)

dB
dBm

Null

Thermistor

in Degrees C
in Degrees F
Statistics
Mean
Variance
Count
Limits
3-73. Math operations can only be done on instrument
acquired measurement data.
3-74. A Math operation is selected by first pressing the
front panel's blue MATH button and then pressing the
desired math key. The blue label below the froct panel's
numbered keys shows the various math operations. An
located to the center and below the display also
LED,
lights when a math operation is selected. The registers
used in the math operations are identified by the white
labels above the numbered keys. The range of numbers
you can store into the registers or use in math is from
0.0000 00 x 10 - 9 to 1999999 x 10 9 . The 3456A does,
±
however, do internal calculations using 9 digit noating
point numbers. If any of the math calculations are out
of range, an "LL" is displayed. The following describes
the 3456A's math operations.
3·75. %Error.
3-76. The %Error math feature of the 3456A can best
be described by the formula:
Results in percent
where is the present measurement value and "Y"
"X"
is the value in register Y. This formula gives the percent
difference between the reading taken by the 3456A and
the value in register Y. The default (Turn-On or Reset»
value in register Y is 1 . The %Error feature is selected
by the "8" (lOO - Y /Y)] key. Refer to Table I-I for
(X
the %Error accuracy specifications.
3-77. You can use the %Error function to determine
the percent difference between an ideal voltage and a
measured voltage. For example, you may wish to know
the %Error of a 10 V dc measurement. The first thing to
do is to store 10 into register Y. Then set the 3456A to
the %Error math function and take a 10 V measure­
ment. If the reading is exactly 10 V a "0" is displayed.
3·14
- Y
X
x 100
=
Y
If the reading is, for example. 10.1 V, the result
becomes:
�
Y I
X ·
Result
x 100
= - ""
-
Y
showing that the measured value i s 1 % higher than the
ideal value. The number displayed on the front panel
would be " I " .
3·78. S,alo.
3-79. The Scale feature of the -hp- Model 3456A lets
you modify a measurement value by a selected value.
The modification can be done either by addition, sub­
traction, multiplication, or division, depending on how
the Scale function is used. The Scale mode is repre­
sented by the formula:
Results
where is the present measurement value, "Y" is
"X"
the value in reg ister Y and "Z" is the value in register Z.
The default (Turn-On/Reset) values in register Y and Z
are I and 0, respectively. The Scale math feature is
selected by the "7" - Z)/Y] key. Refer to Table I-I
((X
for Scale accuracy specifications.
3-80. To do an addition or a subtraction, first enter a
" I " into register Y. If you wish to perform an addition,
enter a negative number into register
is desired, enter a positive number into register
Scale formula then becomes:
X ( ± Z )
Results
-
=
1
To perform a division, enter a "0" into register Z and
the divisor value into register Y. The Scale formula then
becomes:
Results
=
Multiplication is performed by dividing the measured
value by the inverse of the multiplier value (a fraction).
Here again, a "0" is to be entered into register
the inverse value going into register Y.
3·81. PasS/hil (limit Test'.
3-82. The Pass/Fail math operation can be used to
make a voltage or ohms measurement and to then deter­
mine if the reading falls within certain limits. The limits
are selectable from the 3456A's front panel and should
be stored into the instrument's UPPER and LOWER
registers. Once the limits are stored and the Pass/Fail
math operation is selected, the 34S6A can then be set for
a regular volts or ohms measurement. If the measured
Model 3456A
O
x 100 .01 x lOO
= =
I O
X · z
y
=
If a subtraction
Z.
The
Z.
Z)
X ( ±
= _
X
x · o
y y
-- = -
with
Z
I