Keithley 237

+
SECTION3
IEEE-488
Reference
3.6.9
K -
EOI
and Bus
Hold-Off
Purpose
Format
Parameters
Default
Description
Programming
Notes
Programming
Example
To
enable/
disable
EOI
and
bus
hold-off
on
X.
Kn
KO
K1
K2
K3
Enable
EO!
Disable
EO!
Enable
EO!.
Disable
EO!
Enable
bus
hold-off
on
X
Enable
bus
hold-off
on
X
Disable
bus
hold-off
on
X
Disable
bus
hold-off
on
X
Upon
power-up,
or
after receiving a
OCL, SOC,
or
JOX
command,
the
instrument de-
faults to
KO
(both
EOI
and
bus
hold-off
on
X enabled).
The
EOI
line provides one
method
to positively identify
the
last byte
in
the
data
string
sent
by
the
instrument.
When
enabled,
EOI
is asserted
with
the last byte the
instrument
sends
over
the
bus.
Bus hold-off allows
the
instrument
to temporarily
hold
up
bus
operation via the
NRFD line
when
it
receives
the
X character until all commands are processed. Hold-
off will ensure
that
all
commands
have
been
executed
at
the
time the
bus
is released.
Typical hold-off times
are
discussed
in
paragraph
3.7.
1.
Some controllers rely
on
EOI
to terminate their
input
sequences. Suppressing
EOI
may
cause
the
controller sequence to hang.
2.
When
reading
the
entire
sweep
buffer, EOI
is asserted only
at
the
end
of
the
trans-
mission.
3.
When
enabled,
EOI is asserted
with
the
last byte
in
the
terminator
(if
enabled),
or
with
the
last byte
in
the
data
string
if
the
terminator
has
been
disabled.
4.
When
bus
hold-off is enabled, all
bus
activity is
held
up
for
the
duration
of
the
hold-off
period-
not
just the activity associated
with
the
Model236/237
/238.
10
20
OUTPUT
716;
"K1X"
OUTPUT
716;
"K2X"
+
!
No
EOI,
hold-off
on
X
! Send
EOI
with
last byte,
do
not
hold-off
on
X
3-37