Sun Microsystems Desktop SunStation Sun-3/75 Manual page 38

24
Sun-3/75
Hardware
Installation
Manual
EEPROM
Contents
2.9.
Asynchronous
Serial
Ports
NOTE
Connecting
a
Modem
to
the
Sun-3/75
Banner and configuration data are also retained
in
the
EEPROM;
for
more
infor-
mation, please see Installing
Unix on
a Sun
Workstation,
part
number
800-1317.
You
may
attach
modems,
printers, plotters, or other
serial
devices
which
use
the
RS-232-C
or
RS-423
interface, to
the
serial
port connectors labeled
SERIAL
PORT
A
and
SERIAL
PORT
B on
the
enclosure backpanel.
Each
Sun-3/75
serial
port provides a 25-pin connector (DB-25) compatible with
RS-232-C equipment
All signals in
our connector
are semantically the
same
as
their
RS-232-C
counterparts.
However
the Sun-3/75 uses
improved
electrical
circuits
which, while working with RS-232-C
devices, are also compatible with
the
newer RS-423
standard.
The
serial
ports
on
the Sun-3/75
were
designed
for
connecting
to
peripherals such
as printers
and
plotters,
and can
drive these output
lines at speeds
up
to 19.2 kilo-
baud; input
lines
may
be driven
to 9.6 kilobaud.
All
ports
provide
DTR,
RTS, and
clock
signals,
and
receive
DSR, CTS,
and
DCD
signals.
All ports
are
wired
as
Data Terminal Equipment (DTE)
ports
(which
means
Transmit Data from
the
workstation
is
on pin 2 and Receive Data from
the
peripheral
is
on
pin
3),
and
thus
allow
direct
connection of Data Communications
Equipment (DCE)
such
as
modems.
Computers,
terminals,
printers,
and
other
DTE
devices can
also
be connected
directly to the
serial
ports
by
using
the null
modem
cable available
from
Sun,
part
number
530-1056. For
further
informa-
tion refer
to
System
Interface
Manual
for the
Sun
Workstation
(part
number
800-
1173), section
ZS(4S),
which
discusses the Zilog
serial interface.
Signals carried
on
the
SERIAL
PORT A
and
SERIAL
PORT
B
connectors
are listed
in the appendix.
The
following sections
—
which
describe connecting modems,
terminals,
and
printers to the serial ports
—
are
guidelines only,
and
specific
devices
may
require
more
detailed information such as
that
contained
in the
System
Interface
manual.
The
serial ports are
wired
as
DTEs, and most
modems
arc
wired
as
DCEs. The
cable
connecting your
modem
to the
Sun-3/75 should be
"straight
through"
—
the signals
on
pins
2, 3, 4, 5, 6, 7, 8,
and 20
at
the output of
the cable should be
the
same
as those signals
on
corresponding pins of
the
serial port.
Do
not use
a
null
modem
cable
to
connect
the
serial port to
your
modem.
It
does not matter
which
serial port
you connect
to;
both
are identical.
Refer
to the
manual which comes
with your
modem
to see
which
signals
you
will
need
for proper operation of your
modem.
Refer
also to
System
Administration
for
the
Sun
Workstation,
part
number
800-1
150,
and
Installing
UNIX on
the
Sun
Workstation,
part
number
800-1317,
which
detail
connecting
to a
modem.
#snn
V
merw
/stems
Revision
A
of 31 September
1986