10/100Base-Tx Pin Assignments; Straight-Through Wiring; Crossover Wiring - AMX NXA-ENET8-2POE Operation/Reference Manual

Cables and Pinouts

10/100BASE-TX Pin Assignments

Use un-shielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for RJ-45 connections: 100-ohm
Category 3 or better cable for 10 Mbps connections. Also be sure that the length of any twisted-pair connection
does not exceed 100 meters (328 feet).
The RJ-45 ports on the switch support automatic MDI/MDI-X operation, so you can use straight-through or
crossover cables for all network connections to PCs, switches, or hubs. In straight-through cable, pins 1, 2, 3,
and 6, at one end of the cable, are connected straight through to pins 1, 2, 3, and 6 at the other end of the cable.
10/100BASE-TX MDI and MDI-X Port Pinouts
PIN
1
2
3
6
4,5,7,8

Straight-Through Wiring

If the twisted-pair cable is to join two ports and only one of the ports has an internal crossover (MDI-X), the
two pairs of wires must be straight-through. (When auto-negotiation is enabled for any RJ-45 port on this
switch, you can use either straight-through or crossover cable to connect to any device type.)
You must connect all four wire pairs as shown in FIG. 24 to support Gigabit Ethernet connections:
FIG. 24
Straight Through Wiring

Crossover Wiring

If the twisted-pair cable is to join two ports and either both ports are labeled with an "X" (MDI-X) or neither
port is labeled with an "X" (MDI), a crossover must be implemented in the wiring. (When auto-negotiation is
enabled for any RJ-45 port on this switch, you can use either straight-through or crossover cable to connect to
any device type.)
You must connect all four wire pairs as shown in FIG. 25 to support Gigabit Ethernet connections:
FIG. 25 Crossover Wiring
28
MDI Signal Name *
Transmit Data plus (TD+)
Transmit Data minus (TD-)
Receive Data plus (RD+)
Receive Data minus (RD-)
Not used
*
The "+" and "-" signs represent the polarity of the wires that make up each wire pair.
MDI-X Signal Name
Receive Data plus (RD+)
Receive Data minus (RD-)
Transmit Data plus (TD+)
Transmit Data minus (TD-)
Not used
NXA-ENET8-2POE Gigabit Ethernet Layer 2 PoE Switch