Wiring

Connectors

RJ45 Jack and Plug Pinout.

Cable connector's picture.

Ethernet Cabling

The TIA/EIA-568-A specifies two wiring standards for a 8-position modular connector such as RJ45. The two wiring standards, T568A and T568B vary only in the arrangement of the colored pairs. We are using T568B.

Straight-Through Cable Pinout (T568B):

RJ45 Pin #       Wire Color      10Base-T Signal     1000Base-T Signal
                   (T568B)      100Base-TX Signal
   1             White/Orange       Transmit+           BI_DA+
   2             Orange             Transmit-           BI_DA-
   3             White/Green        Receive+            BI_DB+
   4             Blue               Unused              BI_DC+
   5             White/Blue         Unused              BI_DC-
   6             Green              Receive-            BI_DB-
   7             White/Brown        Unused              BI_DD+
   8             Brown              Unused              BI_DD-

Cross Over Cable Pinout (T568B):

RJ45 Pin #     Wire Color         RJ45 Pin #     Wire Color    
 (END 1)                           (END 2)
   1          White/Orange           1          White/Green
   2          Orange                 2          Green
   3          White/Green            3          White/Orange
   4          Blue                   4          White/Brown
   5          White/Blue             5          Brown
   6          Green                  6          Orange
   7          White/Brown            7          Blue
   8          Brown                  8          White/Blue

NOTE: The cross over cable layout is suitable for 1000Base-T operation, all 4 pairs are crossed.

The following diagram shows the Normal use of Crossed and Straight cables:

straight--HUB,SWITCH--crossed--HUB,SWITCH--straight--PC

PC--crossed--PC

NOTE': To avoid the need for Crossed cables many vendors provide UPLINK ports on Hubs or Switches - these are specially designed to allow the use of a STRAIGHT cable when connecting back-to-back Hubs or Switches. Read the manufacturers documentation carefully.

RS-232 Cabling

RS-232   Name/Function      DB-25          DB-9             RJ-45           RJ-45
Signal   (Input/Output)     (Standard)    (Standard)  (Cyclades)   (Netra/Cisco)
Chassis  Safety Ground              1          Shell        Shell        Shell
Gnd      Signal Ground              7            5            4            4
TxD      Transmit Data (O)
RxD      Receive Data (I)
DTR      Data Terminal Ready (O)
DSR      Data Set Ready (I)
DCD      Data Carrier Detect (I)
RTS      Request To Send (O)
CTS      Clear To Send (I)