Wiring a LAN socket.

[ericmark]

I realised I had got something wrong, so got a TACKLIFE NETWORK TESTER HOST with the idea of finding my errors.

On plugging in it showed as expected the wires in wrong order although all were connected. The easy end to correct was the socket, so plugged main bit into base unit and using know good lead connected to socket with remote thinking it would now be simply a case of swapping a few wires.

However it did not go as planned after starting I could not get all 8 lights, and however many times I tried cutting it all off and starting again I could not get even 8 lights, never mind in the right order.

Clearly there have to be two wires connected before any lights show on the slave, but after first two were connected I expected each lamp to come on as I punched the cable in.

Any advice welcome before I have another go tomorrow.

 

[bernardgreen]

Bit late now but a simple tester can be made with a PP3 battery, 9 resistors, a tag board and an RJ45 plug ( or socket ).

At the far end use a high impedance voltmeter to find the pair with the highest voltage. They are wires 1 and 8 from then each wire can be identified by the voltage on it relative to wire 1

 

[ericmark]

At £10 it was cheap enough However the instructions are not that comprehensive, and I am reading the advert states:-
Feature:
1.Test twisted pair wires 1, 2, 3, 4, 5, 6, 7, 8, one by one (pair by pair) to tell which one (pair)
goes short circuit or open circuit. If there are shielding twisted pair wire on both terminals
light G turns on.
2.The standard version can test RJ45 and RJ11.
3.There are three switch locations for operation. "OFF" means turn off the devices. "ON"
means normal speed test. "S" means slow speed test.
4.This device can use host to test network wires connected with exchangers (not applicable
for exchangers without filter capacitor.

I wonder if it does not do as I expected? I thought base unit on the plug and slave on the socket, I would see each wire show up as connected, so I could work away at the socket end where it's easy enough to swap wires until it was all correct, however worked out where the two browns went, but as I added the other cables nothing showed for most, yet I know plug is good as all lights worked, be it in wrong order to start with, so only looking at changing wires at socket.

If pair by pair and I have the order completely wrong maybe it will not show, I did retest a know good lead just in case got something wrong, looking at the plug to see order is not easy, one can only see 1/4" of colour, I think the original problem was I expected the socket to be wired in order 1234 and 5678 or 1357 and 2468 however this web site seems to show a really odd order, 2135 and 7864 which if correct would explain my error.

 

[bernardgreen]

There are two standards which differ in which pins the green and blue pair connect to. In most application provided the green and blue pairs use teh same pins at each eand the cable is good. There are some applications where the green and blue use different pins to conect RX at one end to the TX at the other end where both devices have TX on the same pins. The cable is then a "cross connect" the same as a null modem cross connects TX and RX between devices.

I think in your case the confusion may be in the connections ( on a PCB ? ) between the Punch Down terminals and the pins in the plug ( or socket ).

is how the last one I made up was organised.

 

[rsgaz]

differ in which pins the green and blue pair connect to.

Green and orange BTW. Blue and brown are always wired straight through.

Eric, can you show us a picture of the back of the modules you have? They pretty much always have a colour code on them, even if some brands are more useful than others...


i.e. useless colour code(made by Molex, surprisingly), doesn't show which side of the ink blob that the whites go...

Decent colour code, doesn't bother showing the 568A code, which no-one outside of the USA uses. Just 568B...

 

[bernardgreen]

My error. It is Green and Orange that exchange.

I never did find out why one pair uses pins 3 and 6, instead of two ajacent pins like the other three pairs. Anyone got any ideas why ?

 

[ericmark]

I got the multi-meter out and rang out connections with cable in at bottom left top down was 3, 6, 7, 8, right down 5, 4, 1, 2 once I knew that it was easy, and now LAN works OK.

Had I been wiring socket to socket or plug to plug it would have been OK, it's only when wiring a plug to a socket that simple left top to left top does not work.

 

[rsgaz]

instead of two adjacent pins like the other three pairs. Anyone got any ideas why ?

To make it backwards compatible with telephone systems, USOC(pair 1 and 2 at least), token ring, etc.

Pair 1 needs to always take the middle pins for a jack with only 2 pins wired...

...which only leaves three on each side of course.

 

[bernardgreen]

Logical, why didn't I see that. Thanks

 

[Astra99]

If you hold the RJ45 plug with the retaining clip downwards, from the left the cables are:
1 - Orange/White, 2 - Orange, 3 - Green/White, 4 - Blue, 5 - Blue/White, 6 - Green, 7 - Brown/White and 8 - Brown

This is replicated at the socket as per Bernard Green's post above.

There are many RJ11/45 cable testers available, one example is http://cpc.farnell.com/duratool/d03052/network-cable-tester/dp/IN07336 which is currently offered at £2.34 + VAT & delivery. Other testers may be purchased, both from CPC and other suppliers.

 

[ericmark]

My son tells me my tester is cheap and nasty, his it seems gives a report on which cables have been swapped. However I will guess it cost a lot more. With my tester if you can plug in both ends of the lead without splitting it into the two sections you can see both 1,s both 2,s etc light up, however where the two ends are some distance apart the master will light is sequence and you can go to the slave and watch that light in sequence however you have no idea as to if both 1,s are lighting together.

I thought it would be easy, once two wires fitted you should see an extra LED light on the slave as each wire was added, however this was not the case, as to why I don't know, once I realised the socket was not wired in sequence I got it all working and at that point stopped.

I am sure all testers show you when all is OK and make it easy to make contact with the pins, however some will also work with power over LAN, some will give distance to fault etc. But all working now so why worry.

 

[Astra99]

When you set the tester going at the "main" end, the lights will run through the sequence in order, from 1-8 then Ground. At the remote end, if the lights do not run in order, but jump around, the connections have been made incorrectly, and the way the lights are jumping around will allow you to deduce which connections are incorrect. I have just bought a set which will also show PoE. This is on a separate connection on the "master" and LEDs illuminate to indicate which pair(s) the power is on. I agree, it would be lovely to see the light illuminate at the remote end as the connections were made, but I have yet to find a tester to do this which is at a reasonable price.