Shermie's Place

RJ45

Shermie's Place
Electrical Electronic RJ11 RJ45 RS232
Straight Through Cable Wiring Cross Over Cable Wiring
RJ-45 Pin # Color (both sides identical)
Pin 1 White with Orange
Pin 2 Orange
Pin 3 White with Green
Pin 4 Blue
Pin 5 White with Blue
Pin 6 Green
Pin 7 White with Brown
Pin 8 Brown

RJ-45 Pin #

 1 Side Color 2 Side Color
Pin 1 White with Orange White with Green
Pin 2 Orange Green
Pin 3 White with Green White with Orange
Pin 4 Blue Blue
Pin 5 White with Blue White with Blue
Pin 6 Green Orange
Pin 7 White with Brown White with Brown
Pin 8 Brown Brown

About the Cable:

You want UTP (Unshielded Twisted Pair) Category 5 cable for basic 10/100 functionality. You need CAT 5e for gigabit (1000BaseT) operation and CAT 6 gives you a measure of future proofing. Bulk cable comes in many types, there are 2 basic categories, solid and braided cable. Braided cable tends to work better in "patch" applications for desktop use. It is more flexible and resilient than solid cable and easier to work with, but really meant for shorter lengths. Solid cable is meant for longer runs in a fixed position. Plenum rated cable should/must be used whenever the cable travels through an air circulation space. For example, above a false ceiling or below a raised floor.


  Internal Cable Structure and Color Coding

Inside the cable, there are 8 color coded wires. These wires are twisted into 4 pairs of wires, each pair has a common color theme. One wire in the pair being a solid or primarily solid colored wire and the other being a primarily white wire with a colored stripe (Sometimes cable doesn't have any color on the striped cable, the only way to tell is to check which other wire it is twisted around). Examples of the naming schemes used are: Orange (alternatively Orange/White) for the solid colored wire and White/Orange for the striped cable. The twists are extremely important. They are there to counteract noise and interference. It is important to wire according to a standard to get proper performance from the cable. 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.

 

How to wire Ethernet Cables:

  1. Strip off about 2 inches of the cable sheath.
  2. Untwist the pairs - don't untwist them beyond what you have exposed, the more untwisted cable you have the worse the problems you can run into.
  3. Align the colored wires according to the diagrams above.
  4. Trim all the wires to the same length, about 1/2" to 3/4" left exposed from the sheath.
  5. Insert the wires into the RJ45 end - make sure each wire is fully inserted to the front of the RJ45 end and in the correct order. The sheath of the cable should extend into the RJ45 end by about 1/2" and will be held in place by the crimp.
  6. Crimp the RJ45 end with the crimper tool
  7. Verify the wires ended up the right order and that the wires extend to the front of the RJ45 end and make good contact with the metal contacts in the RJ45 end.
  8. Cut the cable to length - make sure it is more than long enough for your needs. Remember, an end to end connection should not extend more than 100m (~328ft). Try to keep cables short, the longer the cable becomes the more it may affect performance, usually noticeable as a gradual decrease in speed and increase in latency.
  9. Repeat the above steps for the second RJ45 end.
  10. If a cable tester is available, use it to verify the proper connectivity of the cable.

That should be it, if your cable doesn't turn out, look closely at each end and see if you can find the problem. Usually a wire ended up in the wrong place or more commonly, one of the wires didn't extend to the front of the RJ45 connector and is making no, or poor contact. If you see a mistake or problem, cut the end off and start again.