Cisco AGS+, Hardware Installation And Maintenance

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Applique
and Cable
Pinouts
RS-449
DCE
and
DIE Apphques
The RS-449
DTE
applique contains
male
37-pin connector
while the
RS-449
DCE
applique
contains female
37-pin connector
The
internal
ribbon cable connects
to
the 26-pin connector
The
mode
is
labeled
on
the circuit
card either
RS-449
DTE
or
RS-449
DCE
The RS-449
DCE
applique
is
shown
in Figure
A- 10 and
the
RS-449
DTE
is
shown
in Figure
A-li
The RS-449
DCE
applique requires that
the clock
be
supplied
from
the
MCI
card or the
SCI card
The
DCE
applique
contains an additional jumper
field
W2
which
selects the
transmit data clock
source
Pins
and
of
W2
are
jumpered
together causing the
applique
to
expect
to
see the transmit
clock on the
serial
clock transmit external
SCTE/TT
lines
of
the
interface cable
It is important
that the
DTE
attached
to this
interface returns
SCTE/TT
along
with
its
data
to
avoid
cable-induced clock
problems
This
is
the factory default
and
it is
the
recommended
setting
for
reliable
operation
at
high data rates
If
the
DTB
device does not return clock on
SCTEITT
connecting pins
and
of
W2
together causes the
DCE
applique
to use the outgoing
clock
serial
clock transmit
SCT/ST
instead of
SCTEITT
The RS-449
DTE
applique
see
Figure
A-li
returns transmit clock on
SCTE/TT
This
is
designed
to
compensate
for clock
phase
shifting
on
long cables It
is
important
that the
DCE
device connected
to
the
DCE
applique
modem
be
configured
to
accept
SCTE/TT
Figure
A-b
RS-449
UCE AppliqueComponent-Side View
A-16
AGS
Hardware
Installation
and Maintenance