HP 8508A - Page 51

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SYSTEMS
3-11
REMOTE
OPERATION
-
THE
HEWLETT-PACKARD
INTERFACE
BUS
The
Vector
Voltmeter
is
capable
of
remote
operation
via
the
Hewlett-Packard
Interface
Bus
(HP-IB)
which
is
Hewlett-Packard’s
implementation
of
IEEE
Standard
488.1.
This
section
gives
details
of
remote
operation,
includ-
ing
capabilities,
addressing,
input.and
output
formats,
status
and
service
requests.
All
front
panel
functions,
except
the
LINE
switch,
are
programmable
via
HP-IB.
In
addition,
there
are
HP-IB
commands
offering
capabilities
under
remote
control
which
are
not
available
from
the
front
panel
keyboard.
The
HP-IB
commands
used
in
the
Vector
Voltmeter
conform
to
the
standards
set
by
document
IEEE
488.2-1987,
“Codes,
Formats,
Protocols
and
Common
Commands
for
use
with
ANSI/IEEE
Std
488.1,
22
January
1987”.
Consult
the
standards
document
for
details
of
the
commands
and
structures
recommended.
For
more
information
about
HP-IB,
refer
to
IEEE
Standard
488.1
(or
the
identical
ANSI
Standard
MC1.1),
the
Hewlett-Packard
Electronic
Systems
and
Instruments
catalog,
the
booklet
“Improving
Measurements
in
Engineer-
.
ing
and
Manufacturing”
(HP
part
number
5952-0058),
and
“Tutorial
Description
of
the
Hewlett
Packard
Interface
Bus”
(HP
part
number
5952-0156,
Nov
87).
Anyone
who
is
unfamiliar
with
the
IEEE
488
Standards
should
read
the
Tutorial
Description
as
an
introduction.
HP-IB Capability
This
section
gives
a
general
description
of
HP-IB
capabilities
as
they
apply
to
the
Vector
Voltmeter.
The
instru-
ment’s
command
set
is
summarised
in
Table
3-2
and
command
details
are
given
in
the
Command
Reference
section.
HP-IB
system
operation
normally
relies
on
three
types
of
bus
device
behaviour,
as
follows:
*
A
LISTENER
is
capable
of
receiving
data
over
the
bus
when
addressed
to
do
so.
There
can
be
multiple
listeners simultaneously active.
*
A
TALKER
is
capable
of
transmitting
data
over
the
bus
when
addressed
to
do
so.
There
can
be
only
one
active talker at atime.
*
A
CONTROLLER
specifies
the
talker
and
listener(s)
for
an
information
transfer,
including
itself.
There
can
be
only
one
active
controller
at
a
time.
Local
and
Remote
Operation
The
Vector
Voltmeter
can
operate
under
either
local
or
remote
control.
In
local
mode
all
front
panel
controls
are
operational
and
control
the
instrument.
In
remote
mode,
all
front
panel
controls
are
inoperative
(except
[LCL]
when
not
in
Local
Lockout),
the
instrument
being
controlled
by
the
HP-IB
controller.
The
front
panel
display
reflects
the
remote
programming
commands
received,
unless
the
display
is
switched
off.
At
power-on,
the
instrument
assumes
the
local
state.
Under
local
contro!
all
HP-IB
instrument
commands
will
be
ignored.
To
gain
control
over
HP-IB
the
controller
must
put
the
instrument
into
the
remote
state.
This
is
accom-
plished
by
setting
the
Remote
Enable
(REN)
bus
control
line
true
and
sending
the
Vector
Voltmeter’s
HP-IB
Listen
Address.
:
In
local
mode,
the
Vector
Voltmeter’s
front
panel
controls
are
fully
operational
and
it
will
respond
to
the
Remote
message.
Whether
it
is
addressed
or
not,
it
will
also
respond
to
the
Clear,
Local
Lockout
and
Clear
Lockout/Local
messages.
When
addressed
to
talk,
the
Vector
Voltmeter
can
issue
Data
messages
and
the
Status
Byte
message.
Whether
addressed
or
not,
it
can
issue
the
Service
Request
message.
*
E1089
.
3-27.