HP 3468A - Chapter III: Programming With HP-IL; Introduction to HP-IL Programming; Understanding HP-IL Interface

introa
ction
Your -hp- Model 3468A Digital Multimeter was designed to interface with a varie-
ty
of
calculators
and
computers
over
the
Hewlett-Packard
Interface
Loop
(HP-IL).
This
chapter
discusses
the
programming
and
remote
control
of
the
3468A
from
the
-hp-
Model
41C/41CV
family
of
handheld
calculators.
The
many
features
of
the
3468A
combined
with
the
computational
power
of
the
41C/41CV
calculator
provides
for
low
cost,
flexible
measurement
systems.
In
addition,
printer/plotters
and
cassette
mass
storage
devices
can
easily
be
added
to
the
interface.
Chapter
IV
shows
remote
programming
using
a
BASIC
language
computer
such
as
the
-hp-
Model 85.
This
chapter
shows
you
how
to
execute
simple,
one
line
commands
from
the
calculator
to
control
the
3468A,
and
then
read
measurement
data
back.
Later
we'll
discuss
interface
control
operations
and
the
development
of
powerful
pro-
grams
for
controlling
the
3468A.
Last,
you'll
look
at
several
application
programs
including
a
simple
data
logger
with
a
printer
and
cassette
drive.
Before
beginning
this
chapter
you
will
want
to
have
read
Chapter
Il
of
this
manual
so
that
you
are
familiar
with
the
many
features
of
the
3468A.
You
will
also
find
it
helpful
to
have
read
the
-hp-
Model
82160A
HP-IL
Module
Owners
Manual
(-hp-
part
number
82160-90001)
and
the
-hp-
Model
41C/41CV
Owners
Handbook
and Programming
Guide (-hp- part number 00041-90313).
What is HP-IL?
The
Hewlett-Packard
Interface
Loop
(HP-IL)
is
a
two
wire
serial
interface
that
pro-
vides
programmable
control
of
instruments
while
being
easy
to
use
and
under-
stand.The
calculator
and
all
devices
in
the
loop,
including
the
3468A,
are
con-
nected
together
in
series,
forming
a
continuous
loop
communications
circuit.
Any
information
(instructions
or
data)
that
is
transferred
among
HP-IL
devices
is
passed
from
one
device
to
the
next
around
the
loop
(one
direction
only).
If
the
information
is
not
intended
for
a
particular
device,
that
device
simply
passes
the
information
on
to
the
next
device
in
the
loop.
When
the
proper device
receives
the
informa-
tion,
that
device
responds
as
directed.
In
this
way,
the
calculator
or
the
3468A
can
send
information
to
and
receive
information
from
each
device
in
the
loop,
ac-
cording to the device’s capability.
29