Lantronix
SM4T4DPA Install Guide
33867 Rev. A
Page
23
of
29
Cables
Twisted-Pair Cable and Pin Assignments
For 10/100BASE-TX connections, the twisted-pair cable must have two pairs of wires. For 1000BASE-T
connections the twisted-pair cable must have four pairs of wires. Each wire pair is identified by two different colors.
For example, one wire might be green and the other, green with white stripes. Also, an RJ-45 connector must be
attached to both ends of the cable.
Caution
: DO NOT plug a phone jack connector into any RJ-45 port. Use only twisted-pair cables with RJ-45
connectors that conform with FCC standards.
Caution
: Each wire pair must be attached to the RJ-45 connectors in a specific orientation. The figure below
illustrates how the pins on the RJ-45 connector are numbered. Be sure to hold the connectors in the same
orientation when attaching the wires to the pins.
RJ-45 Connector Pin Numbers
10BASE-T/100BASE-TX Pin Assignments
Use unshielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for RJ-45 connections: 100-ohm Category 3
or better cable for 10 Mbps connections, or 100-ohm Category 5 or better cable for 100 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 base unit support automatic MDI/MDI-X operation, so you can use straight-through
cables for all network connections to PCs or servers, or to other 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. When using any RJ-45 port on this switch, you can use either straight-through or crossover cable.
10/100BASE-TX MDI and MDI-X Port Pinouts
Pin
MDI Signal Name
MDI-X Signal Name
1
Transmit Data plus (TD+)
Receive Data plus (RD+)
2
Transmit Data minus (TD-)
Receive Data minus (RD-)
3
Receive Data plus (RD+)
Transmit Data plus (TD+)
6
Receive Data minus (RD-)
Transmit Data minus (TD-)
4, 5, 7, 8 Not used Not used
Note
: The “+” and “-” signs represent the polarity of the wires that make up each wire pair.