1257 User Manual
Computer Interfaces 4-2
EADS North America Defense
Test and Services, Inc.
©
2001
Using the
Ethernet Interface
Basic Ethernet
Information
The Ethernet standard provides a way to interconnect devices on a
common network covering long distances. A network may contain
as few as two
nodes
(devices). A network connecting more than
two devices requires the use of a hub, but these are inexpensive
and readily available, and simple to connect. They allow many
devices to interconnect and communicate with one another.
To use Ethernet with the 1257 Switching System, you need a
computer equipped with an Ethernet port and an Ethernet cable.
Ethernet Cabling
Guidelines
The 1257 uses a CAT-5 Ethernet cable, consisting of four twisted-
pair wires terminated by a standard RJ-45 modular plug at each
end.
To connect the 1257 to an Ethernet hub, use a CAT-5 cable that is
constructed in a “straight-through” configuration:
Connector 1
Connector 2
Pin 1 (TX+)
Pin 1 (TX+)
Pin 2 (TX-)
Pin 2 (TX-)
Pin 3 (RX+)
Pin 3 (RX+)
Pin 6 (RX-)
Pin 6 (RX-)
Pins 4, 5, 7, 8: Unused
To connect the 1257 directly to the RJ-45 port on a computer, use
a CAT-5 cable that is made in a “crossover” or “reverse”
configuration:
Connector 1
Connector 2
Pin 1 (TX+)
Pin 3 (RX+)
Pin 2 (TX-)
Pin 6 (RX-)
Pin 3 (RX+)
Pin 1 (TX+)
Pin 6 (RX-)
Pin 2 (TX-)
Pins 4, 5, 7, 8: Unused
