Table of Contents
Advertisement
4708
Use
MODE
Now
the
DMM
gain error
may
be
measured
4708
4708
offset
value
still
displayed
Merely
set
OUTPUT
display
to
'
+10V
using
1 4
keys
(Of
in
this
case
FR
key)
If
gain
error
is
zero,
^
DMM
agrees
P
with
4708
OUTPUT
display
DMM
-OUTPUT iwNae—
DMM
Offset
still
cancelled
+9.999900
V
-
10.000000V
+
(-
0.000100V)
t
t
t
OUTPUT
-
OUTPUT
-
MODE
display
value
display
setting
Offset
value
Full
Scale
Limiting.
The 4708
will reject
any combination
of
set
value
and
zero
offset
which would
result in
an
off-scale output.
e.g. if-
19.999950V
is
set
together
with
-100|LtV
offset,
the user
is
requesting
an
offscale
output
of
-20.000050V and
the
combi-
nation
is
invalid.
The 4708
causes
Error
5
to
appear
on
the
MODE
display as
a
signal
to
the
user,
and
continues
to
output
its
previous
(valid)
value.
The
OUTPUT
display cannot
be
set to
a
value
greater than Full
Scale.
The
Offset
MODE
display cannot
be
set to
a value
greater than the Offset
span
for die
Range
in use.
i.e.
100p,V
and
ImV
Ranges:
<200|xV
Other Ranges:
<2%
of
Full
Range
value
Deselection
of Offset
Mode
This
clears the
MODE
display, turns the
red Offset
LED OFF
and
reduces
the
4708
offset to zero.
Normally
the
mode
is
de-
selected
by
repressing the Offset key,
but
it
is
also turned off
by
changing
FUNCTION
or
RANGE.
Combining
Offset
and
Error
Modes
(DC
Functions
only)
By
combining
Offset
and
Error
modes
it
is
possible
to
carry out
a
rapid analysis
of a measuring
instrument's
linearity
(e.g.
for
a
DMM
or
A-D
converter)
without
the
need
to
correct
its
zero
offset
and
gain
errors.
This
is
done by
using Offset
Mode
to
compensate
the
4708
ouq>ut
for the
DMMs
zero
offset,
and
then using
Error
Mode
to
compensate
for the
DMM's
gain
error
with
the
offset
compen-
sation
still
present.
In
this
condition,
any
residual deviations
in
DMM
readings
from
the
4708
OUTPUT
display
settings
represent
non-linearities
which would
still
be
present
if
the
DMM
were
corrected
for
offset
and
gain
errors.
This
facility
also
permits
a
user
to
quantify the
linear
response
of
the
instrument
to
its
input values
in
the
form y
=
mx
+
c
in
which
y
=
instrument reading
X
=
input
value
m
=
gain
ratio
c
=
zero
offset
value
4-15
Hide quick links:
Advertisement
Table of Contents
