HP 3468A - Sending Instructions via HP-IL

Command
codes
are
used
to
cause
the
3468A
to
change
states,
i.e.,
make
an ac
measurement
instead
of
a
dc
measurement,
or
perform
a
particular
operation
such
as
output
status
information,
etc.
Look
at
the
blue
page
at
the
end
of
the
previous
chapter.
It
provides
a
description
the
Instruction
Messages
the
3468A
will
res-
pond
to
and
how
they
are
used.
The
underside
of
the
3468A
also
contains
a
table
of
command
codes.
Procedure
Decide
what
you
want
the
instrument
to
do
and
determine
the
appropriate
Com-
mand
Codes.
For
example,
the
Command
Code
for
DC
Volts
is
F1
(Function
1),
the
Code
for
the
3
volt
range
is
R2
(Range
2).
Let's
look
at
an
example
and
break
down
the
instruction
message.
To
set
the
3468A
to
the
DC
Volts
function
and
3
volt
range,
the
following
message
would
be
sent:
interface
3468A
select
code
address
2
instruction
messages
\
/
[_————_
finked
together
OUTPUT
901;”
Fi
R2”
‘sets
function
to
DC
volts
(F
is
mnemonic
and
1
is
qualitier)
computer
output
command
syntax
depends
on
the
computer
being
used.
Figure
4-1.
Instruction
Example
As
you
can
see
from
the
example,
more
than
one
instruction
may
be
sent
to
the
3468A
at
one
time;
any
number
of
instructions
may
be
included
in
the
command
string.
Now,
let’s
take
another
look
at
using
multiple
instructions.
Sample Problem
Suppose
you
need
to
make
an ac
voltage
measurement
between
.20
volts
and
1
volt.
You
also
want
Autozero
on
and
the
measurement
to
be
made
in
the
4
1/2
digit
mode.
What
series
of
instructions
will
achieve
this?
First,
it
is
an ac
voltage
measurement,
therefore
instruction
“F2”
is
used.
You
don‘t
know
exactly
what
range
to
use,
so
use
the
autorange
feature,
“RA”.
The
instruction
for
autozero
on
is
”Z1”,
and
for
the
4
1/2
digit
mode,
“N4”
.
The
command
string
now
looks
like:
“F2 RA Z1 N4”
65