USER’S MANUAL
Section 9: The V.35/X.21 Interface Option 157
9.3
Hook-Ups to Non-ISDN Synchronous Networks
The V.35/X.21 Connection
If
present,
the
V.35/X.21
interface
is
supplied
in
slot
B
slot,
looking
from
the
rear.
It
permits
connection
to
transmission
paths
other
than
ISDN.
It
may
also
be
used
with
external
ISDN
Terminal
Adapters
in
the
(rare)
case
where
the
available
ISDN
service
is
not
compatible
with
the
Zephyr’s
internal
TA,
or
for
emergencies.
?
CURIOSITY NOTE!
You might wonder why the much more common RS-232 is not used. Answer: V.35 is
synchronous, meaning that the bit clock is transmitted between the two ends.
RS-232 is typically used for self-clocking (asynchronous) applications, and requires overhead
start and stop bits, slowing and chopping the bit flow. And, just as with audio, balanced
transmission is more reliable in a noisy environment, or in one which has ground potentials
at differing levels.
V.35
is
a
standard
for
connecting
to
synchronous
digital
data
paths.
Like
RS
‐
232,
it
defines
signals
and
(not
officially)
connectors
and
pin
‐
outs
so
that
equipment
from
various
manufacturers
may
talk
with
each
other.
The
usual
connector
is
a
big
boxy
AMP
type,
which
was
chosen
by
AT&T
decades
ago.
Most
terminal
equipment
sold
for
the
US
market
supports
the
V.35
standard
(although
an
adapter
cable
may
be
required
to
connect
to
the
usual
connector).
The
following
Signals
are
provided
at
the
V.35
end
of
the
Telos
cable:
V.35 CONNECTOR PIN-OUT
Pin
Description
Direction (Xstream
◄►
DCE)
B Ground
C #
RTS (Request to Send)
►
F
CD (Carrier Detect)
◄
H #
DTR (Data Terminal Ready)
►
P *
TX Data
►
R
RX Data
◄
S *
/TX Data
►
T
/RX Data
◄
V RX
Clock
◄
X
/RX Clock
◄
Y TX
Clock
►
AA
/TX Clock
►
Summary of Contents for Zephyr Xstream
Page 2: ......
Page 26: ...USER S MANUAL Section 1 QUICK RESULTS 14...
Page 30: ...USER S MANUAL Section 2 INTRODUCTION Getting to Know the Zephyr Xstream 18...
Page 70: ...USER S MANUAL Section 3 GUIDED TOUR of the HARDWARE 58...
Page 144: ...USER S MANUAL Section 6 AUDIO CODING REFERENCE 132...
Page 164: ...USER S MANUAL Section 8 LIVEWIRETM IP Audio 152...
Page 310: ...USER S MANUAL Appendix 1 Codec Interoperability Information 298...
Page 320: ...USER S MANUAL Appendix 3 ISDN Cause Phrases Values 308...
Page 324: ...USER S MANUAL Appendix 4 Known Working SPID Formats by Telco 312...
Page 356: ...USER S MANUAL Appendix 9 Modular Cable Guide 344...
