RJ45   
 

Opp

 

 

 

 

 

 

 

 

 

Ethernet Cables (10Base-T)


Wiring configuration for Ethernet cables:

Straight Through Cable
(Hub to Device)
1------1
2------2
3------3
6------6

 

Crossover Cable
(Hub to Hub)
1------3
2------6
3------1
6------2

 

10 / 100 BaseT Ethernet maximum cable distance between stations.

Speed

Cable Type

Duplex Mode

Maximum Distance (m)

10 Mbs

Category 3 UTP

Full & Half

100 m

10 Mbs

Multimode Fibre

Full & Half

2000 m

100 Mbs

Category 5 UTP

Full & Half

100 m

100 Mbs

Multimode Fibre

Full

2000 m

100 Mbs

Multimode Fibre

Half

400 m

100 Mbs

Singlemode Fibre

Full & Half

10,000 m

1000 Mbs

Multimode Fibre

Full

260 m


EIA/TIA 568A and 568B

The EIA (Electronics Industries Association) and TIA (Telecommunications Industry Association) establish the standards 568A and 568B. In network wiring, this helps a network manager keep track of the blue wires, the green wires, the red wires, etc. With respect to category 5 patch cables, however, 568A and 568B patch cables are interchangable because the pins match on both ends; only the "colors" of the wires inside the RJ45 plugs will be different. Below is what the pinning looks like:


Crossover
Cable
Straight Through
Cable
RJ-45
PIN
RJ-45
PIN
RJ-45
PIN
RJ-45
PIN
1 Rx+ 3 Tx+ 1 Tx+ 1 Rc+
2 Rc- 6 Tx- 2 Tx- 2 Rc-
3 Tx+ 1 Rc+ 3 Rc+ 3 Tx+
6 Tx- 2 Rc- 6 Rc- 6 Tx-

Ethernet RJ45 Socket 10baseT

Pin No.
Description.
Color
1
TX +
White w/Orange
2
TX -
Orange
3
RX +

White w/Green

4
 
Blue
5
 
White w/Blue
6
RX -
Green
7
 
White w/Brown
8
 
Brown

RJ45 MaleRJ45 Female

RJ45 Cross Over Cable

RJ45 Male
 
RJ45 Male
1
 
3
2
 
6
3
 
1
6
 
2

 

RJ45 100base-T4 Crossover male to male

Name
Pin
Pin
Name
TX_D1+
1
3
RX_D2+
TX_D1-
2
6
RX_D2-
RX_D2+
3
1
TX_D1+
RX_D2-
6
2
TX_D1-
BI_D3+
4
7
BI_D4+
BI_D3-
5
8
BI_D4-
BI_D4+
7
4
BI_D3+
BI_D4-
8
5
BI_D3-
It's important that each pair is kept as a pair. TX+ & TX- must be in the pair, and RX+ & RX- must together in another pair etc. (Just as the table above shows).
 

Ethernet Cables

Okay, here is the basic information you will need to make your own ethernet cables.

Parts: You'll need several feet of CAT 5 cable, RJ45 ends and an RJ45 crimper to complete this. You'll also need a nice cut-off plier. A wire striper and a cable tester are greatly helpful aswell.

Cable: First, start off with good quality cable, it has to be UTP (Unshielded Twisted Pair) Category 5 cable, don't skimp on this (Shielded works too, but isn't necessary). Bulk cable comes in many types, there are 2 basic categories, patch and riser cable. Patch cable is meant for desktop use, it is more flexible and resiliant than riser cable, its easier to work with, but really meant for shorter lengths. Riser cable is meant for longer runs through walls and ceilings. Your likely going to want patch type cable. Plenum cable is not needed unless you plan to do a very professional job and will be running wires through walls, ceilings and air conduits etc.

Here is what the internals of the cable look like:

cat 5 cable
Figure 1 - Internal Cable Structure and Color Coding

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 cheap cable doesnt 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. I seem to remember that each pair has a different twist ratio, I believe this would have affect on signalling at higher speeds, so it becomes important to wire according to the standards. Besides, this maintains all your cables to the standards and makes it easy to find errors and cross-over cables. The standard I'm referring to, is primarirly the TIA/EIA-568-A standard. This standard specifies two wiring standards for a 8-position modular connector such as is used in twisted pair ethernet networks. The two wiring standards, T568A and T568B vary only in the arrangement of the colored pairs. As shown below I have chosen T568B for the straight through cable and T568A for the cross-over cable. I believe this to be the most common arrangement for ethernet cables. It is also possible to wire it the opposite way (ie straight through is a T568A). Your choice might be determined by the need to match existing wiring, jacks or personal preference, but you should maintain consistancy.

RJ45 Ends: The RJ45 end is a 8-position modular connector that looks like a large phone plug. There are a couple variations to these plugs, there are models that deal with round or flat or even oval cables, cat 5 should be round. There is also variation in the contacts used in the plug. One type, for stranded wires, which is what would normally be used in a patch cable, has contacts that actually pierce the wire. The second type of contact is for solid wires, typically used in riser type cable. This contact has fingers which pierce the insulation and make contact with the wire by grasping it from both sides. Now I just learned about all these variations recently, so I'm not sure how harmful it is to use the wrong type. It's also pretty impossible to tell in the store what type it is, if the plugs aren't labeled. But the general jist, if possible, use connectors that say stranded for patch type cable, and solid type plugs for riser type cable. I also discovered that you can get plugs that have an extra piece that acts as a wire quide, you fed the wires through it, then insert the piece into the plug, looks pretty handy, I haven't tried it yet. There are many more variations but they are not very important, btw you can add strain relief boots if you want. Here is a diagram and pinout:

rj45 jack pinout rj45 plug
Figure 2 - RJ45 Jack and Plug Pinout

Ethernet Cables: Now, on to the cables. There are two basic cables. A straight through cable, which is used to connect to a hub or switch, and a cross-over cable used to operate in a peer-to-peer fashion without a hub/switch. Gigabit copper interfaces can actually cross and un-cross a cable automatically as needed, really quite nice. Since you are making your own cables, I will assume you understand which cable you need.

Standard, Straight-Through Wiring (both ends are the same):

RJ45 Pin #

Wire Color

Wire Diagram

Signal*

1

White/Orange

white/orange

Transmit+

2

Orange

orange

Transmit-

3

White/Green

white/green

Receive+

4

Blue

blue

Unused

5

White/Blue

white/blue

Unused

6

Green

green

Receive-

7

White/Brown

white/brown

Unused

8

Brown

brown

Unused

Table 1 - Straight-Through Cable Pinout
* For 10BaseT and 100BaseTX


Cross-Over Cable:

RJ45 Pin # (END 1)

Wire Color

Diagram End #1

1

White/Orange

white/orange

2

Orange

orange

3

White/Green

white/green

4

Blue

blue

5

White/Blue

white/blue

6

Green

green

7

White/Brown

white/brown

8

Brown

brown

RJ45 Pin # (END 2)

Wire Color

Diagram End #2

1

White/Green

white/green

2

Green

green

3

White/Orange

white/orange

4

Blue

blue

5

White/Blue

white/blue

6

Orange

orange

7

White/Brown

white/brown

8

Brown

brown


Tables 2 & 3 - Cross-Over Cable Pinouts

If you look closely, you will noticed that the green and orange pairs are swapped or crossed, these are the transmit and receive pairs.

Procedure: To create the cable, strip off about 2 inches of the cable sheath. When you get to the second side, cut the wire to length and make sure it is more than long enough for your needs. Remember, an end to end connection should extend at least 1m (3ft) and not more than 100m (~328ft). Yes, there is a minimum, its little known, little referred to and not usually important, but I have seen cases where short cables caused problems. The longer the cable becomes the more it may affect performance, usually it is a gradual decrease in speed and increase in latency. When uplinking between (cascading) hubs/switches, you usually need a very short cable, less than 1m, check the device's specifications.

Next 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.

Now you want to align the colored wires according to the diagrams above. When nicely aligned, hold them in line together and trim them all to the same length, about 1/2" to 3/4" left exposed from the sheath. And then you want to insert them into the RJ45 end and 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. Crimp the end with the crimper tool and once again 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. If you have a cable tester, put it to use, and verify the proper connectivity of your newly made 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.

Startside ] Opp ] [Søk]

Copyright © 2002 Øyvind Haugland
Sist endret:  25 mars 2017
 

  Interested in this stuff? Please write to:
 

HTML Counter            stats counter