Keithley 237 - Page 92

SECTION2
Operation
However,
there
may
be
test
situations
that
require
there-
mote
sense
leads
and
source
leads
to
be
connected
to
dif-
ferent
parts
of
a circuit
that
have
a significant
voltage
dif-
ferential
between
them.
The
maximum
allowable
voltage
difference
between
OUTPUT
LO
and
SENSE
LO
is 4V.
Exceeding
this
volt-
age
difference
between
source
low
and
sense
low
will
re-
sult
in
erratic
operation.
The
maximum
allowable
voltage
differential
(VMAX)
be-
tween
OUTPUT
HI
and
SENSE
HI
is
defined
by
the
fol-
lowing
equation.
Exceeding
this
voltage
difference
be-
tween
source
high
and
sense
high
will
result
in
erratic
op-
eration.
VMAX
=
12
-10(VoUT/VFS)
where;
VMAX
=
Maximum
allowable
voltage
difference
between
OUTPUT
HI
and
SENSE
HI
VoUT
=
Output
Voltage
VFS
=
Full
scale
voltage
range
For
example,
if
5V
is
sourced
on
the
11
V
range,
the
maxi-
mum
allowable
voltage
differential
between
source
and
sense
is:
VMAX
=
12-10(5V
/11V)
=
7.45V
IEEE-488
Bus
Operation
The
0
command
is
used
to
program
sense.
WARNING
With
remote
sensing
enabled,
an
open
sense
lead
will
result
in
lethal
voltages
appearing
at
OUTPUT
HI
and
GUARD.
This
voltage
can
cause
injury
or
death,
and
damage
exter-
nal
circuitry.
Always
make
sure
that
the
sense
leads
are
properly
connected
before
enabling
remote
sense.
NEVER
change
con-
nections
with
power
applied.
Be
sure
to
al-
ways
discharge
and/or
disconnect
external
power
sources.
00
=
Local
sense
01
=
Remote
sense
2-40
+
+
HP
BASIC
4.0
Programming
Examples:
OUTPUT
716;
"01X"
OUTPUT
716;
"OOX"
Select
remote
sense
Select local
sense
Complete
information
concerning
the
IEEE-488
bus
and
this
command
can
be
found
in
Section
3
IEEE-488 Refer-
ence.
2.1
0.4
Ac
Line Frequency
The
Source
Measure
Unit
will
operate
on
an
ac
line
fre-
quency
of
50
or
60Hz.
This
menu
item
allows
you
to
check
or
change
the
line
frequency
setting
of
the
Source
Meas-
ure
Unit.
This
adjusts
the
A/D
converter
to
the
proper
integration
time
for
line
cycle
integration.
To
check
the
present
ac
line
frequency
setting
and
other
menu
operation
item
parameters,
enable
MENU
and
use
the
rotary
knob
to
scroll
through
the
menu
items.
If
no
changes
are
to
be
made,
disable
MENU
to
return
to
the
source-measure
display
state.
Perform
the
following
steps
to
select
the
alternate
ac
line
frequency
setting:
1.
With
MENU
enabled,
turn
the
rotary
knob
until
the
present
ac
line
frequency
setting
is
displayed.
For
ex-
ample,
if
the
line
frequency
is
currently
set
to
60Hz,
the
following
will
be
displayed:
60Hz
ACLINE
2.
Use
the
SELECT
buttons
to
select
the
alternate
set-
ting.
SELECT~
selects
50Hz
and
<IIIII
SELECT selects
60Hz.
3.
With
the
desired
line
frequency
setting
displayed,
press
ENTER
The
next
menu
item
will
be
displayed.
4.
If
no
other
menu
actions
are
to
be
taken,
disable
MENU
to
return
to
the
source-measure
display
state.
NOTE
Changing
the
ac
line
frequency
with
a
front
panel
menu
selection
also
changes
the
inte-
gration
time
if
LINECYCLE PERIOD is
pres-
ently
selected.
For
example,
a
line
frequency
change
from
60Hz
to
50Hz
also
changes
the
integration
time
from
16.667msec
to
20msec.