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196 Appendix D Connectors and pin assignments
209418-A
Table 54 lists the RJ-45 (8-pin modular) port connector pin assignments.
MDI and MDI-X devices
Media dependent interface (MDI) is the IEEE standard for the interface to
unshielded twisted pair (UTP) cable.
For two devices to communicate, the transmitter of one device must connect to the
receiver of the other device. The connection is established through a crossover
function, which can be a crossover cable or a port that implements the crossover
function internally.
Ports that implement the crossover function internally are known as MDI-X ports,
where X refers to the crossover function.
The following sections describe the use of straight-through and crossover cables
for connecting MDI and MDI-X devices.
Table 54 RJ-45 port connector pin assignments
Pin Signal Description
1RX+ Receive Data +
2RX- Receive Data -
3 TX+ Transmit Data +
4 Not applicable Not applicable
5 Not applicable Not applicable
6 TX- Transmit Data -
7 Not applicable Not applicable
8 Not applicable Not applicable
Note: For the transmitter of one device to connect to the receiver of
another device, the total number of crossovers must always be an odd
number.