3Com Router 5000 and Router 6000 v2.41
Module Guide
Chapter 3
Multifunctional Interface Modules (Router 5000)
3-35
Note:
You can select a network interface connectors with an RJ-45 receptacle at both ends that connect two
120-ohm balanced twisted pair cables with BNC connectors. The network interface connector is used in
the extension connection with E1 120-ohm balanced twisted pair cables.
In addition, a 75-ohm to 120-ohm adapter is provided.
For the pinouts of E1cables, see Low-End and Mid-Range Series Routers Cable
Manual.
Caution:
E1 cable, coaxial connector, network interface connector and 75-ohm to 120-ohm adapter are all
optional accessories, you need to order them when purchasing 2-port modules; otherwise, they are not
provided.
II. Conversion cable for 4-port module
4-port modules provide two types of “1-to-4” conversion cables: 120-ohm 4-port
module conversion cable and 75-ohm 4-port module conversion cable. At one end of
these two types of cables is a DB-25 connector used to connect a router, and at the
other end are four DB-15 connectors used to connect E1 cables. You can distinguish
these two types of cables by the main labels. There are the words “4-port module
-120Ohm-CAB “ printed on the main label for 120-ohm 4-port module conversion
cables whereas the words “4-port module -75Ohm-CAB” are printed on the main label
for 75-ohm 4-port module conversion cables.
The two types of cables have a similar appearance, as illustrated in the following
figures. However, a 75-ohm 4-port module conversion cable uses 8-core coaxial
cables but a 120-ohm 4-port module conversion cable uses four twisted pair cables.