X.21 Serial Port
66
SmartNode 4650 Getting Started Guide
D • Port pin-outs
X.21 Serial Port
ISDN BRI 0/0 (NT/Net or TE/User) port
The BRI phone port uses an 8-pin RJ-45 connector (the pinout is shown in
table 18
).
Note
Pins not listed are not used.
Note
All pins between the
port BRI 0/0
and
the port BRI 0/1
are connected during
power failure. Fallback relay operation:
•
When the unit is not powered, the fallback relay connects pins 3, 4, 5, and 6 of the net
and the user ports (fallback) together. This enables you to place calls to the PSTN even if
the unit is powered down.
•
Line power applied to the
Line
port is fed through to the
Phone
port at all times and
independent of the fallback relay’s status.
Table 17. X.21 Female DB-15 connector
X.21 Interface Pin-Out
Pin
Signal
1
Signal Ground
2
TD-a
3
Control-a
4
RD-a
5
Indication-a
6
Signal Element Timing (Clock) -a
8
DTE Common Return
9
TD-b
10
Control-b
11
RD-b
12
Indication-b
13
Signal Element Timing (Clock)-b
Table 18. RJ-45 socket
Pin
Signal
3
Rx+
4
Tx+
5
Tx-
6
Rx-
