5
7409
The
two
serial
ports
on
the
7409
I/O
Board
have
jumper
options
for
either
Ring
Indicator
(RI),
fused
+12
V,
or
fused
+5
V.
When
set
to
powered
each
port
is
capable
of
supporting
up
to
1.5
A
(Max.)
and
is
protected
with
self
‐
healing
poly
‐
fuse.
The
default
setting
is
Ring
Indicator
.
The
power
is
selectable
by
JP4.
26705c
COMA/COMB - JP4
12
1
COMA +5V
COMA +12V
Pin 3 - 4
Pin 1 - 2
Pin 5 - 6
COMA Ring Indicator *
COMB +5V
COMB +12V
Pin 9 - 10
Pin 7 - 8
Pin 11 - 12 COMB Ring Indicator *
* Default settings
