~
HP
5384A and
HP
5385A
SYSTEMS
•
a Ope,atoon and Pmg,.mm;ng
3-107. INTERFACE FUNCTIONAL
OVERVIEW
3-108.
Each
device
on
the
interface may
possess
one
or
more
of
the
following
major device capabilities:
Controller,
Talker,
or
listener.
The
controller,
as
the
name implies,
has
the
responsibility
to
control
inter-
face activity. The
controller,
of
course, must be
equip-
ped
with
the
proper
interface
module.
Controllers
transmit all device
independent
commands
to
other
devices
in
the
interface and usually have Talker and
listener
capabilities. The
counter
cannot
serve
as
a
controller.
3-109. Talkers are devices
that
have
the
ability
to
send data
or
device
dependent
commands
through
the
interface.
Note
that
a
talker
will
not
actually send
its data
or
information
until
told
to
do
so
by
the
controller.
The
counter
has
Talker capabilities. In
special
situations,
one
device may be classified
as
a
Talk-only device and sends
information
to
listen-only
devices. Such a system
would
not
have a
controller.
For example,
the
counter
can be
configured
to
the
Talk-only
mode
and send measurement results
to
a
printer.
(TALK ONLY
Address=
31).
3-110.
listeners
are devices
with
the
capability
to
receive
information
over
the
interface.
listeners
must
also be enabled by
the
controller
to
receive
the
information.
3-111. INTERFACE SYSTEMS TERMS
3-112. The
following
paragraphs
define
the
terms
and concepts used
to
describe HP-IB and HP-IL
system operations.
a.
ADDRESS:
Each
device in
the
interface
is
as-
signed
an
address. The address
is
used
to
specify
which device on the interface
will receive
information
or
send information.
b.
BYTE:
A byte
is
a
unit
of
information
consisting
of
eight
binary digits called bits.
c.
DEVICE:
Any
instrument
or
unit
that
is
HP-IB
or
HP-IL
compatible
is
called a device.
d.
DEVICE DEPENDENT: An action a device
per-
forms in response
to
information
sent
through
the
interface. The action
is
characteristic
of
a particular
instrument
and will
probably
vary
from
device
to
device.
e.
DEVICE INDEPENDENT
COMMAND:
A
com-
mand
predefined
by
the interface standard
to
have a
specified
bit
pattern and resulting action.
3-12
f.
DEVICE
DEPENDENT
COMMAND:
A
com-
mand
not
predefined
by the interface standard,
which
is
specific
to
a particular
instrument
or
family
of
instruments.
g.
POLLING: Polling
is
a process typically used by
a
controller
to
locate a device
that
has
requested
service
from
the
controller.
There are
two
types
of
polling;
Serial Poll and Parallel Poll:
1.
Serial Poll.
When
the
controller
executes a
serial
poll,
the
addressed device sends
one
byte
of
operational
information
called a status
byte.
If
more
than
one
device in the interface
is
capable
of
requesting service, each device
on
the
interface must be serial
polled
until
the
device that requested service
is
located.
2.
Parallel Poll.
When
the
controller
executes a
parallel
poll,
all devices
on
the
interface re-
spond, each
one
setting
or
clearing a particular
data
bit
to
indicate
whether
or
not
it
requested
service.
3-113. ADDRESS SELECTION
3-114.
MANUAL
ADDRESSING.
To
use
the
counter
in
a system, set
the
rear panel address
switches
to
the
desired address. Addresses 0
through
30
represent
the
addressable
mode
range. Address
31
selects
the
Talk-only
mode.
The addressable
mode
is
used
when
the
counter
functions
as
a
talker
and a
listener. The TALK ONLY
mode
(Figure 3-10)
is
employed
when
the
counter
is
operating
in
an
output-only
condition
(no
controller
on
the bus) and
sends its data
to
another
device on
the
bus, such
as
a
printer,
set
to
LISTEN
ONLY.
ADDRESS
16
8 4 2
•
0
A7
As
As
A4
A3 A2
A1
L
LNOTUSED
FOR
INTERNAL
TESTS
Figure
3-10.
HP 5384A
and
HP
5385A Address Switches
Shown in Address
31
•
•
•
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