... .
THE HP-IB
What
Is The HP-IB
The
Hewlett-Packard
Interface Bus is an easy to use, high performance bus struc-
ture
that
links the
3314A
and
other
instruments,
desktop
computers
and
minicom
-
puters
into
automated measurement systems. The HP-IB is a
worldwide
instrumen-
tation
interface standard
(IEEE
Standard
488-1978,
ANSI Standard MC 1.1 and
IEC Recommendation
625·1).
How
Does The HP-IB Operate
All
of
the
active
interface
circuits
are contained
within
the
various HP-IB devices.
The
interconnecting
cable is entirely passive. The cable's role is limited to connec-
ting
all
of
the
devices in parallel, so
that
data can be transferred
from
one device
to another.
Every participating device
must
be able
to
perform at least one
of
these roles:
TALKER, LISTENER, or CONTROLLER. A TALKER
transmits
data
to
other devices
called LISTENERS.
Most
devices can perform
both
roles,
but
not
at
the
same time.
A CONTROLLER manages
the
operation
of
the
bus system by designating
which
device is
to
Talk
and
which
device(s) are
to
Listen at any given
time
. The
3314A
can be a Talker and a Listener,
however,
it
has no Controller capabilities.
The
minimum
HP-IB system consists
of
one TALKER and one LISTENER
without
a
CONTROLLER. In
this
configuration, data transfer is
limited
to
one direction
because one device
must
be manually
set
to
"TALK
ONLY" and
the
, other device
must
be manually set to " LISTEN
ONLY".
The
3314A
can be set to Listen Only,
but
not
to
Talk
Only.
The
full
flexib
ility
and
power
of
the
HP-IB is realized
when
a controller is added
to
the
system. An HP-IB controller participates in
the
measuren:ent
when
programmed to
schedule measurement tasks, set up instruments,
monitor
the
measurements, and
analyze
the
results.
All examples in this section use
the
-hp-
9000
Series
200/300
computer
and
the
BASIC
4.0
programming language.
81
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