4.3.2 DUAL COAX BNC (75 OHM) CONNECTION
The Model 2703RC-A DB15/Coax rear card is equipped with dual
female BNCs (TX and RX) for connection to a 75 ohm dual coax G.703
network interface. The outer conductor of the coax cables is isolated
from system earth ground.
4.4 CONNECTION TO THE TERMINAL DEVICE
The Model 2703RC-A rear cards are wired as Data Circuit-
Terminating Equipment (DCE) and are designed to connect directly to
Data Terminal Equipment (DTE).
4.4.1 EIA-530 (RS422) and V.35 TERMINAL CONNECTION
The DB25 connector of the Model 1000RCM703120 rear card is
configured as DCE (see the wiring diagram in Appendix C). To con-
nect to a V.35 or EIA-530 DTE device, use a
straight-through DB-25
cable. NOTE: The 120 ohm rear card must be set for non-synchro-
nized clocking (See Section 3.2.1) in order to support the EIA-530 or
V.35 interfaces.
4.4.2 X.21 TERMINAL CONNECTION
The DB15 connector of the Model 2703RC-A is equipped with a
female DB-15 connector and is, wired according to the ITU/CCITT
X.21 standard (see the wiring diagram in Appendix C). To connect to
to an X.21 terminal (DTE), use a
straight-through DB-15 cable.
Note: The 120 ohm rear card can also be used with X.21 terminal
devices. To do this, the card must be set for synchronized clock-
ing (See Section 3.2.1), a DB-25 to DB-15 adapter cable must be
used. See Appendix B for the adapter cable part numbers. Or,
you may construct your own cable using the diagrams in
Appendix C.
15
Notice!
Any coaxial cable connected to the dual coax rear
card must incorporate an outer shield that has no less than
90% coverage.
Notice!
Any terminal cable connected to the Model 2703RC
must be shielded cable, and the outer shield must be 360
degree bonded–at both ends–to a metal or metalized backshell.
55..00
O
OPPEER
RA
ATTIIO
ON
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Once you have configured each Model 2703RC-A and connected
the cables, you are ready to operate the units. Section 5.0 describes
the power-up procedure, LED status indicators and the built-in loop-
back test modes.
5.1 POWER-UP
There is no power switch on the Model 2703RC-A: Power is auto-
matically applied to the Model 2703RC-A when its card-edge connec-
tor makes contact with the chassis’ mid-plane socket, and when the
chassis’ power supply is turned on.
Note: The Model 2703RC-A is a
“hot swappable” card—it will not be damaged by plugging it in or
removing it while the rack is powered up.
5.2 LED STATUS MONITORS
The Model 2703RC-A features four front panel LEDs that monitor
power, network connection, master clock and loopback. Figure 8
(below) shows the front panel location of each LED. Following Figure
7 is a description of each LED’s function.
Power
Glows green when the Model 2703RC-A receives
operational power.
Network
Glows green when the Model 2703RC-A is receiv
ing correctly encoded data from the line interface
equipment.
Master Clock Glows green when the Model 2703RC-A is
configured as the master clock unit.
Loopback
Glows green when the Model 2703RC-A is in
loopback mode.
16
Figure 8. Model 2703RC-A front panel, showing LED indicators.
Model 2703
Power
Network
Master
Clock
Loopback
Normal
