I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

I can see how the wires in the pair to terminals 7 and 8 are kept
together, as are the pair to 1 and 2.

But you have to untwist the pair going to terminals 6 and 3, as the
wires in this pair are on opposite sides of the block. You also have
to untwist the pair going to 4 and 5.

If keeping the twist right up to the terminal block is important, why
isn't the IDC block arrangement as follows:

4 X X 6

5 X X 3

8 X X 1

7 X X 2

or am I missing something?

On Sun, 08 Jul 2007 03:22:03 -0700, Pandora
mused:

I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

I can see how the wires in the pair to terminals 7 and 8 are kept
together, as are the pair to 1 and 2.

But you have to untwist the pair going to terminals 6 and 3, as the
wires in this pair are on opposite sides of the block. You also have
to untwist the pair going to 4 and 5.

If keeping the twist right up to the terminal block is important, why
isn't the IDC block arrangement as follows:

4 X X 6

5 X X 3

8 X X 1

7 X X 2

or am I missing something?

No, you're looking at it too closely, just punch the cables down and
screw the cover on.
--
Regards,
Stuart.

On 8 Jul, 11:22, Pandora wrote:
I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

I can see how the wires in the pair to terminals 7 and 8 are kept
together, as are the pair to 1 and 2.

But you have to untwist the pair going to terminals 6 and 3, as the
wires in this pair are on opposite sides of the block. You also have
to untwist the pair going to 4 and 5.

If keeping the twist right up to the terminal block is important, why
isn't the IDC block arrangement as follows:

4 X X 6

5 X X 3

8 X X 1

7 X X 2

or am I missing something?

I don't know if that ascii depiction of the IDC block is coming out
correctly but the distance between the two columns of four is 15mm,
whereas the distance between pins in each column (e.g. between pins 7
and 8) is 4mm.

"Pandora" wrote in message
ups.com...
I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

I can see how the wires in the pair to terminals 7 and 8 are kept
together, as are the pair to 1 and 2.

But you have to untwist the pair going to terminals 6 and 3, as the
wires in this pair are on opposite sides of the block. You also have
to untwist the pair going to 4 and 5.

If keeping the twist right up to the terminal block is important, why
isn't the IDC block arrangement as follows:

4 X X 6

5 X X 3

8 X X 1

7 X X 2

or am I missing something?

This might help:

http://www.tlc-direct.co.uk/Technica...Networking.htm

Note that there are two standards for connection (568A and568B). It doesn't
matter which you use, as long as they are the same at both ends!

The arrangement of the wires and pins is all to do with minimising crosstalk
between the wires in the cable.

David

On 8 Jul, 12:00, "DavidM" wrote:
"Pandora" wrote in message

ups.com...

I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

I can see how the wires in the pair to terminals 7 and 8 are kept
together, as are the pair to 1 and 2.

But you have to untwist the pair going to terminals 6 and 3, as the
wires in this pair are on opposite sides of the block. You also have
to untwist the pair going to 4 and 5.

If keeping the twist right up to the terminal block is important, why
isn't the IDC block arrangement as follows:

4 X X 6

5 X X 3

8 X X 1

7 X X 2

or am I missing something?

This might help:

http://www.tlc-direct.co.uk/Technica...Networking.htm

Note that there are two standards for connection (568A and568B). It doesn't
matter which you use, as long as they are the same at both ends!

The arrangement of the wires and pins is all to do with minimising crosstalk
between the wires in the cable.

David

Thanks

I understand about two standards for connection but my question is
about the physical laying of the wires, rather than the colour of the
sheaths.

I wondered why the manufacturer had laid the IDC connectors out that
way and whether I was misunderstanding why two pairs terminated on
opposite side of the terminal block.

Pandora writes:
I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)
....
I wondered why the manufacturer had laid the IDC connectors out that
way and whether I was misunderstanding why two pairs terminated on
opposite side of the terminal block.

Because thats the way they did it? Some of Leviton's jacks are that
way too. But they seem to change the layout from model to model.
Its probably cheaper for them to produce the circuit boards with the
wiring like this that matches the way the wires actually are inside
the jack itself.

As long as you can punch down reasonably you should pass certification
no problem, its not like they're going to produce something that won't.

Other manufacturers do it differently.

Personally, I like the Hubbell XJack layout which does keep the pairs
together (and angeled) as far into the connector as they can.

Pandora wrote:
I wondered why the manufacturer had laid the IDC connectors out that
way and whether I was misunderstanding why two pairs terminated on
opposite side of the terminal block.

Its just simply the way a particular manufacture laid out the printed
circuit board connecting the IDC punch downs to the jack pins. Its not a
critical or important thing to worry about.

A Hubble brand 568B physical layout looks like this:

Gold pin side
Pin 2 Orange/White Pin 8 Brown/White
Pin 1 White/Orange Pin 7 White Brown
Pin 4 Blue/White Pin 6 Green/White
Pin 5 White/Blue Pin 3 White/Green

Here all associated pairs are on the same sides of the jack.


A Leviton brand 568B physical layout looks like this:

Gold pin side
Pin 2 Orange/White Pin 7 White Brown
Pin 1 White/Orange Pin 8 Brown/White
Pin 3 White/Green Pin 6 Green/White
Pin 5 White/Blue Pin 4 Blue/White

With the Leviton, the orange and brown pairs terminate on the same sides of
the jacks, and the blue and green pairs are split on opposite sides of the
jack.

On a side note, an ethernet jack is properly called an 8-pin jack, but us
old timers often still incorrectly call it an RJ45 jack.

In comp.dcom.cabling Pandora wrote in part:
On 8 Jul, 11:22, Pandora wrote:
If the pins in the front of the socket are numbered 1-8 left to right,

.... assuming tab down, this is conventional numbering

4 X X 6
[bl] [gr]
5 X X 3

8 X X 1
[br] [or]
7 X X 2


I don't know if that ascii depiction of the IDC block is coming
out correctly but the distance between the two columns of
four is 15mm, whereas the distance between pins in each column
(e.g. between pins 7 and 8) is 4mm.


This is a nice layout, it minimizes the pair untwist.
Punch down as marked above for T-568-B. For T-568-A,
swap the orange and green pairs. Colors on evens.

-- Robert

On 8 Jul, 14:49, DTC wrote:

A Leviton brand 568B physical layout looks like this:

Gold pin side
Pin 2 Orange/White Pin 7 White Brown
Pin 1 White/Orange Pin 8 Brown/White
Pin 3 White/Green Pin 6 Green/White
Pin 5 White/Blue Pin 4 Blue/White

With the Leviton, the orange and brown pairs terminate on the same sides of
the jacks, and the blue and green pairs are split on opposite sides of the
jack.

That's the same as the MK Electric brand. I think that the Hubble
brand layout is better but there you go. (I use MK because the network
sockets match the profile of the power sockets - it's an aesthetic
thing.)

OK, now I know that there's no problem, I'll just wire up as everybody
has suggested.

Thanks, guys.

Pandora wrote:

I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

If it is appropriately Cat5 or Cat6 certified then there is
no reason to worry about the arrangement. I would say it
is a little easier to design for high frequencies if the
two for a pair were closer, but it isn't that hard either way.

Most that I remember have the wires of the pair opposite each other
(like (4,5) and (6,3) in your example) for all pairs. It might
be a little easier to punch down that way.

-- glen

On Sun, 08 Jul 2007 14:27:02 -0800, glen herrmannsfeldt
wrote:

Pandora wrote:

I am wiring up some RJ45 network sockets for the first time. (MK
Electric part K5845 - available in UK)

If the pins in the front of the socket are numbered 1-8 left to right,
then the corresponding connections on the IDC block on the rear are
arranged as follows:

4 X X 5

6 X X 3

8 X X 1

7 X X 2

Why is this arrangement used?

If it is appropriately Cat5 or Cat6 certified then there is
no reason to worry about the arrangement. I would say it
is a little easier to design for high frequencies if the
two for a pair were closer, but it isn't that hard either way.

Most that I remember have the wires of the pair opposite each other
(like (4,5) and (6,3) in your example) for all pairs. It might
be a little easier to punch down that way.

-- glen


All of what you say is true, Glen, but Leviton, and obviously MK,
chose to do it this way. I've used Leviton for several years, and,
with the Rapid Jack tool, it's not so bad to fan the wires and seat
them all at once. The jacks have a lower profile than most and it
fits in a Leviton surface mount housing better than anythng else, so I
keep going back to them.

Carl Navarro

Carl Navarro wrote:
All of what you say is true, Glen, but Leviton, and obviously MK,
chose to do it this way. I've used Leviton for several years, and,
with the Rapid Jack tool, it's not so bad to fan the wires and seat
them all at once.

How many jacks did your Rapid Jack Tool do before the cutting blades got
dull and started mashing up the jack? Mine has started damaging the jacks
after only a hundred or so jacks.

On Tue, 10 Jul 2007 00:36:54 GMT, DTC
wrote:

Carl Navarro wrote:
All of what you say is true, Glen, but Leviton, and obviously MK,
chose to do it this way. I've used Leviton for several years, and,
with the Rapid Jack tool, it's not so bad to fan the wires and seat
them all at once.

How many jacks did your Rapid Jack Tool do before the cutting blades got
dull and started mashing up the jack? Mine has started damaging the jacks
after only a hundred or so jacks.

I confess, I only use it for high productivity and that means two jobs
so far for about 160 jacks. I am really careful to seat the jack in
the slot before I crimp it. I don't get it out for one or two jacks.
I have the eversharp 110 blade...and BTW don't drop it on the tile
floor bacause Murphy says it will always fall point first. Especially
when you're in a hurry.

Carl