PacComm TINY-2 - RS-232 and TTL Port Configuration

COMPUTER
INTERFACING
RS-232
Port
Signals
COMPUTER
INTERFACING
The
TINY-2/MIGRO-2
packet
controller
communicates
with
the
com-
puter
or
terminal
through
a
serial
port
using
either
RS-232C
or
“TTL”
level
signals.
One
of
these
signal
levels
should
properly
interface
to
most
computers.
See
the
Appendices
to
this
manual
for
specific
computer
interfacing
instructions.
RS-232
Port
Signals
2
The
serial
port
connectors
on
the
TINY-2/MICRO-2
packet
controller
are
on
the
rear
pane!
marked
“RS-232"
and
“TTL
Computer.”
The
pins
onthe
serial
port
connector
of
packet
controller
that
must
be
connected
are
shown
in
the
following
table.
This
is
commonly
called
a
“three-wire”
RS-232
cable.
RS-232
Serial
Port
“3
Wire”
Cable
Wiring
for
DB-25
Computer
DB-25_TINY-2/MICRO-2
RS-232
Serial
Port
“3
Wire” Cable
Wiring
for
DE-9
Computer
DE-9_TINY-2/MICRO-2
5
and
shell
-------
The
packet
controller
is
configured
as
Data
Communications
Equip-
ment
(DCE),
the
technical
term
for
an
RS-232C
modem.
Most
com-
puters
and
terminals
are
configured
as
Data
Terminal
Equipment
(DTE).
Specifically,
the
packet
controller
connector
is
an
IBM
“AT
style”
using
a
male
DE-9
connector,
wired
as
DCE
rather
than
DTE.
If
you
use
an
“AT”
PG
or
portable
computer
with
a
9-pin
serial
port,
you
can
wire
cable
connector
pins
2
through
8
directly
(pin
2
to
pin
2,
etc.)
Pin
4
onthe
TINY-2/MICRO-2
is
the
Data
Carrier
Detect
(DCD)
signal
which
goes
high
(true)
when
the
packet
controller
is
in
the
“connected”
state.
This
is
analogous
to
the
DCD
signal
on
telephone
modems,
i.e.
the
pin
is
asserted
when
a
communication
connection
exists.
Pin
9
is
used
as
an
auxiliary
radio
carrier
detect
input.
This
pin
may
also
be
used
when
two
or
more
packet
controllers
are
mated
for
use
with
network
firmware
such
as
the
NET/ROM
or
ROSE
EPROM.
More
detailed
information
is
presented
later
in
the
manual.
Some
computers
require
that
Clear
to
Send
(CTS)
of
the
computer
serial
port
connector
(pin5
of
a
DB-25
or
pin
8
of
a
DE-9)
be
connected
to
an
appropriate
signal.
Others
may
require
connections
tor
Data
Carrier
Detect
(DCD)
{pin
8/pin
1)
and
Data
Terminal
Ready
(DTR)
(pin
TINY-2/MICRO-2
Technical
Ref.,
2
Ed
©
1989,
PacComm,
Inc.