Keithley 237

SECTION3
IEEE-488
Reference
Description
Programming
Notes
3-60
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The
trigger
configuration
command
determines
the
input
trigger
origin,
the
effect
of
an
input
trigger,
and
when
an
output
trigger
is generated.
The
trigger
origin
can
be
over
the
bus,
from
an
external
trigger
pulse,
or
from
the
front
panel.
An
input
trigger
can
be
set
in
a
continuous
or
non-continuous
mode.
Continuous
triggering requires
only
one
trigger
to
complete
a
sweep.
Non-continuous
triggers
can
be
programmed
to
start
the
source, delay,
or
measure
phases,
or
any
combina-
tion
of
phases. A single
pulse
input
trigger
is
intended
for
use
with
pulsed
sweeps,
where
each
trigger
processes
the
toN
and
toFF
times
of
a single
pulse
(see Figure 3-13).
Output
triggers
can
be
generated
after
each
phase
or
combination
of
phases
in
the
5-D-M cycle.
When
the
pulse
end
trigger
is
selected,
an
output
trigger
occurs after
the
measurement
has
been
completed
in
the
toFF
time
of
a
pulsed
sweep.
A
sweep
end
output
trigger
can
be
programmed
by
itself
or
with
another
output
trig-
ger
selection.
When
the
sweep
end
trigger
is
selected, a single
output
trigger is gener-
ated
after
the
sweep
has
returned
to
the
bias level.
This
is
shown
for a
pulsed
sweep
in
Figure 3-13.
1.
It
is
good
programming
practice to disable triggers before
changing
the
trigger
origin.
2.
If
the
instrument
is triggered
while
processing a
previous
command
(i.e.,
during
the
hold-off time),
it
displays
a
PENDING
TRIGGER message.
The
trigger
will
be
acted
upon
when
hold-off
has
completed.
3.
If
the
instrument
is
triggered
while
processing a
previous
trigger,
it
displays
a
TRIG OVERRUN
message
and
the
received
trigger
is
ignored.
4.
For
trigger
on
X,
the
A/D
conversion
time
is
dependent
on
when
the
trigger
is
configured, since
the
instrument
is
triggered
by
the
X character
that
is
sent
when
programming
the
trigger
origin.
5.
For
trigger
on
talk,
the
A/D
conversion
time
is
dependent
on
when
data
is
re-
quested.
To
trigger
the
unit,
you
must
send
the
talk
command
derived
from
the
correct
primary
address.
(The factory
default
address
is
16.) Trigger
on
talk
does
not
occur
when
the
instrument
becomes a talker,
but
rather
as
the
controller
re-
quests
the
first
byte
of
data
from
the
unit.
6.
For
trigger
on
GET,
the
A/D
conversion
time
is
independent
of
when
the
trigger
is configured
and
when
data
is
requested. Trigger
on
GET allows
the
fastest
IEEE-488 triggering response.
7.
Front
panel
triggering
with
the
MANUAL
key
and
bus
triggering
with
the
HOX
command
are
always
enabled
regardless
of
the
programmed
trigger
origin.
However,
the
front
panel
keys
are
locked
out
if
the
unit
is
in
remote
(RMT on). To
restore local
operation
in
this case,
press
the
LOCAL
key.
8. Executing
the
trigger
control (R),
trigger
configuration
(T),
or
source
and
function
(F)
commands
place
the
unit
in
an
untriggered
state.
9.
Refer
to
the
Model236/237
/238
Application
Manual
for suggestions
on
using
triggers
with
multiple
source-measure
units.
10.
With
non-continuous
triggers,
an
additional
input
trigger
is
needed
after
the
measure
phase
of
the
last
sweep
point
to
return
to
the
bias
value.
11. While
in
continuous
triggering
of
the
de
mode,
the
unit
can
be
reprogrammed
without
having
to
retrigger it.
12. Valid triggers received after
programming
continuous
triggers
are
ignored.
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