Pin Designations - Radio Shack 26-1145 Hardware Manual

Pin Designations
and
Signal Descriptions
The
mechanical
specification
of the
RS-232-C
requires
a
25-pin
connector
(called
a
DB-25). Table
2 specifies
the pin assignments
and
signal
descriptions
as
they apply
to the
Radio Shack RS-232-C
Interface.
Pin
Number
Abbreviation Description
1
PGND
Protective
Ground
2
TD
Transmit Data
3
RD
Receive Data
4
RTS
Request-to-Send
5
CTS
Clear-to-Send
6
DSR
Data
Set
Ready
7
SGND
Signal
Ground
8
CD
Carrier
Detect
20
DTR
Data Terminal Ready
22
Rl
|
Ring
Indicator
TABLE
2.
PEN
DESIGNATIONS
AND
SIGNAL DESCRIPTION
Protective
Ground:
This
must
be
bonded
to the
chassis
or
equipment
frame.
It
may
also
be connected
to Signal
Ground.
Transmit
Data: Direction-to data
communication
equipment.
Signals
on
this circuit are generated
by
the data terminal
equipment
for
transmission of data
to
remote equipment.
This
signal
should be
held
in
the
marking
condition during
intervals
between
characters
and
at
all
times
when
no
data
is
being transmitted.
Received Data: Direction-from data
communication
equipment.
Signals
on
this circuit are
received
from remote equipment which
transmits data to the terminal. This
signal
should be held
in
the
marking condition during
intervals
between
characters
and
at
all
times
when
no
data
is
being
received.
Request-to-send: Direction-to data communication equipment.
This
signal
is
required
by
the terminal
equipment
to
control the
direction
of
data transmission
by
the data
communication
equipment.
On
one-way
or
duplex
channels, the
"on"
condition maintains the
data
communication equipment
in
the transmit
mode. The
"off"
condition maintains the data communication equipment
in
the
non-transmit
mode.
On
a
half
duplex
channel, the
"on"
condition maintains the data
communication equipment
in
the transmit
mode
and
inhibits
the
receive
mode. The
"off" condition maintains the data
communication
equipment
in
the receive
mode.