Eagle TX Series AMOS Based Terminal Server Technical Manual, Rev. 01
Appendix A -
Connector
Configurations
The rear panel of your terminal server contains all serial connectors for the serial ports included in your
terminal server, one parallel connector for the parallel port, and the Ethernet connector (either standard 15
pin connector and /or the RJ-45 10BaseT Ethernet connector) for attaching the terminal server to your
network. This appendix discusses connector and cable considerations for both network and serial
connections.
ETHERNET RJ-45 10BASET CONNECTOR
The Ethernet RJ-45 10BaseT port functions exactly like a DB-15 Ethernet AUI port. In fact, both of these
ports use the same Ethernet driver. The following section explains some of the technical aspects of
Ethernet networking, as well as the cable pinouts required when using the 10BaseT (RJ-45) interface
connector.
10BaseT Topology and Cabling
Ethernet networks were originally designed to be multi-point networks arranged as a bus topology. That
meant that Ethernet would work over coaxial cable (either thick or thin) with 50 ohm termination at each
end of the network, and each computer would attach directly to the same cable.
With the introduction of 10BaseT, Ethernet can be connected via inexpensive twisted pair (Level 5
compliant) cabling, with each computer having its own RJ-45 termination. As a result however, the
network topology is changed so a central repeater or "hub" is required to rebroadcast both data and
Ethernet control signals to all other computers connected to the Ethernet. Such repeaters are commonly
available from commercial sources.
10BaseT connections use 100 ohm unshielded twisted pairs, with at least two pairs per cable (one set of
pairs for transmitting data and another for receiving). 10BaseT cables terminate in eight pin RJ-45
connectors with the following pin assignments:
Pin
Signal Name
1
Transmit Data +
2
Transmit Data -
3
Receive Data +
6
Receive Data -
The other pins are unused.
The 10BaseT specification allows a maximum distance of 100m (approx. 300 feet) between the computer
and hub.
