HP-HIL Devices
Introduction
Hewlett-Packard HUlllan Interface Link (HP-HIL) is
an
HP
standard
for interfacing Series 300
computers
and
other
workstations
to
human
input
devices. A list
of
HP-HIL
devices is shown
in Table
~~-11.
Asynchronous serial communications protocol enables you
to
select a set
of
input
devices, con-
nect thern
to
your
computer,
and
work
with
any application program.
A link controller
on
the
system
interface
board
controls
the
HP-HIL.
Each
HP-HIL
device
has
an
circuit
to
interface information
to
and
from
the
device.
Limitations
for
the
HP-HIL
are:
•
Up
to
seven devices
can
be
on
the
link.
•
Maximum
distance
between devices is 2.4 metres,
total
link
maximum
length
is
16.8
metres.
This
does
not
include
the
15
or
30
metre
extensions.
• Series 300
Maximum
link
current
is
1 A.
Link
Controller
A block
diagram
of
a typical link controller is shown in
Figure
3-26.
I
Power
I
+12V
Supply
J
GND
HP-HIL Data
so
51
HP-HIL Data
Computer
Unk
Interface
J1
1\
\I V
Sy.tem
Micro-
I
~
1\
proc:enor
System-Specific
Components
'\I
V
Figure 3-26. HP-HIL Link Controller Block Diagram
Power Supply
One
voltage,
+12
Vdc
is
taken
from
the
host
computer
and
output
as a regulated power supply
to
external
devices
on
the
link.
Up
to
1 A
can
be
supplied
to
devices.
When
configuring
HP-HIL
devices
with
Series 300
computers,
care
must
be
used
to
ensure
the
total
power
drawn
by all
devices does
not
exceed 1 A.
In
Table 3-11, devices
are
listed
with
their
power requirements.
Functional Description
109
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