curious question on T-568-B network pin out & wiring

b network pin

Hi,

I am curious to find out why our computer network cable
have the follow color scheme standard.
Why don't they choose to arrange the twisted pair
just next each other, instead of being split up like pin 3 & 6.

Any reasons you can think of?

Pin # T-568-B
------ --------------
1 White/Orange
2 Orange
3 White/Green
4 Blue
5 White
6 Green
7 White/Brown
8 Brown


Best Regards,
Siong Boon

how to find the network pin

siongboon said:

Hi,

I am curious to find out why our computer network cable
have the follow color scheme standard.
Why don't they choose to arrange the twisted pair
just next each other, instead of being split up like pin 3 & 6.

Any reasons you can think of?

Pin # T-568-B
------ --------------
1 White/Orange
2 Orange
3 White/Green
4 Blue
5 White
6 Green
7 White/Brown
8 Brown


Best Regards,
Siong Boon

Click to expand...

Pin5 must be Blue/White!
I think this pin/pair assignment come from no longterm history when there're 2 type of cables: "Crossover" and "Straight-through" . 1-st one to connect PC-PC, 2-nd one for PC-network devices (HUB, Switch, Router,...).
You can find that there're 2 types of pin/pair assignments :T-568-B and T-568-A.
So looking to 2 ends of cable, if A-A (or B-B) => "Straight-through" cable, or if A-B => "Crossover".
Almost of people are difficult to define the order number of connector pin (from left or from right ?) so they're hard to know about the type of cable!. The easiest way to look at the 3-th pin (from left or right is not matter b'cause pin3 and pin6 are symmetrial !) then compaire its color with the side pin!

rj11 pinout 1 pair

Hi Thanhlongbin,

Thank you for pointing out the mistake... My typo error.
I am still not convince.
It is quite difficult to look at the wire color from the lever side.
The way to get a better view would be at the pin side.

Why not they design it this way?

Pin
------
1 White/Orange
2 Orange
3 White/Green
4 Green
5 White/Blue
6 Blue
7 White/Brown
8 Brown


Any other good reason and references to the origin?
I am really very puzzle why don't they arrange
the colored wire neatly.
There must be a good reason behind.

Thank you for more feedback.

t568 assignment

OK, I have an another version :
T568-A/B or "8 positions 8 contacts" 8P8C sometime is called RJ-45 that's a twisted pair cable modular jack. The RJ jack family comes from telephone line system with the famous RJ11 for telephone set that is in use still now. All the RJxx have the similar form factor.
RJ11 is 6PnC, n=2 or 4 for different types of telephone sets.
RJ11 pin configuration
Pin#........pair#.........Purpose
1..............3..............RJ25 usage
2..............2 ............ power supply/dial pulse
3..............1..............tip/ring
4..............1...............ring/tip
5..............2...............power supply/dial pulse
6..............3...............RJ25 usage
RJ11-6P2C is most popular now b'cause the modern telephone set use tone dialing and does not require additional power supply. RJ11-6P4C is used in some Central Office as CO line. You can see that 2 central pins are in 1 pair and 2 outter pins are in another pair. This configuration is for cross-connection safety.
As a child of RJ family, RJ45(8P8C) has to follow backward compatibility with RJ11 (6P4C) so 2 central pairs are the same as RJ11 but 2 new pairs are in outter sides. The pin pair configuration becomes as you described.
I hope this explaination is acceptable.
Best regards
Thanhlongbin

two pin rj-11 pinout tip and ring

Hi Thanhlongbin,

Thank you very much for your explanation.
I think I can relate a bit already.
The 8 pin doesn't seems to be very similar to the 6 pin layout,
but if I relate 8 pin to a 4 pin layout, it make some sense to me.

Thank you.
Siong Boon