# CAT5 dilemma

### Help Support The Rocketry Forum:

##### Well-Known Member
I'm stumped. I ran a new network line to a computer in my office. My son had a roll or wire that he got for a good price on eBay. I'm beginning to think it wasn't such a good deal. He ran a line at his house, tested it with his tester and mine and couldn't get it to work properly. I figured he just configured something wrong and used the same wire. I've done this several times before and I'm confident that I put the connectors on right. The tester I used to check it checks each line individually and it said that I had 8 good lines. I'm not entirely positive how the tester works because it seems to me that to check continuity on 8 conductors you'd need another conductor. Anyway, it said the wire was good. I connected it to the computer and got the "network wire disconnected" message. So I ripped the wire out and ran another one. Same problem. Having run out of things to try I went out and bought a 50' cable with plugs. It works fine. I'm totally baffled. I used connectors from two different sources and it's not the first time I've done this so I've got to assume it's the wire but I have no clue how that can be. Anybody got an idea?

#### clreynolds

##### Well-Known Member
Bill,

You didn't mention the type of connectors you are using, or the type of cable. Not to get too technical, but there are two types of cable: solid core, and stranded core. Just like in electrical wiring, solid core is for use inside walls, and should be terminated with punch-down or presure connectors (jacks) where the splicing pieces form a V. The stranded core is for use outside of walls for drop cords between jacks and devices, and is usually terminated with clear crimp-on RJ45 connectors. These use a single blade of metal for each wire with piercing pins.
If you try to crimp RJ45 connectors onto solid core wiring, you might get a connection to work for a while (if your lucky). The pins will peirce the jacket, but not the wire itself. But they always fail eventually. I talk to people all the time that say they got this to work, but I have replaced more of these than you can count.
Second, the wiring pattern is important, the standards are 568A or 568B. But the real issue is making sure to keep wiring pairs together. The only wires/pins that are needed to get ethernet working are:
pair 1: pins 1 & 2
pair 2: pins 3 & 6
These two pairs are usually green and orange. Which is pair 1 and which is pair 2, is the only real difference between 568A and 568B.

Hope this helps.

##### Well-Known Member
Didya use pro style crimpers for the connectors at
both ends or el cheapo's from a dollar store??

Also did you connect both ends the same way or
did you mirror the order of wiring on the other end?

Cat5 is a tricky animal and you gotta keep your
wits about it or it'll go all wonky on you...
:confused2:

#### o1d_dude

##### 'I battle gravity'
TRF Supporter
Cat-5 cabling is a curious beast. It may be an issue of the cable pairs being "straight through" or "crossover".

Check H E R E for more information. See the 568A and 568B diagrams in particular.

##### Well-Known Member
The blue and brown pairs are always the same,
its only the orange and green pairs that gets
swapped in crossover...

Do not mirror the pairs in the other end of cable...

Cheap crimpers do not put enough pressure in the
connectors to ensure proper connection...

Please PM me with mailing info and I'll whip up
a 50 - 100 foot Cat5e that's tested and guaranteed to work ....

##### Well-Known Member
Thanks for the replies.

Solid wire and punch-down jacks although I've done the RJ45 plugs before with no problem and the tool for those looks to be of good quality. I've used it many times before.

The cables are wired as 568B and the jacks are color coded so I don't think I screwed that up.

I was thinking that maybe I had crossed a couple of the wires but I was really careful. The tester I used is the kind that plugs into both ends of the cable with 8 leds on each end. They light up in sequence and both ends match.

Thanks for the offer of the cable but I did get it working with a 50' cable I got at Home Depot. Not exactly the best place for any kind of quality parts for anything but they are nearby.

The really weird part is the "network cable disconnected" message. For the computer to know the cable was disconnected it would have to know that it was connected at one time. The router thinks it's connected to something because the activity light flashes. Could that happen if one wire of the two pairs is bad?

#### clreynolds

##### Well-Known Member
The really weird part is the "network cable disconnected" message. For the computer to know the cable was disconnected it would have to know that it was connected at one time. The router thinks it's connected to something because the activity light flashes. Could that happen if one wire of the two pairs is bad?
Consider that message as "Poorly worded". That is the message you get whenever a cable is not connected. Not just that status has changed. It is possible to have one end or the other showing a link if the receive pair on that end is connected. But without both TX and RX it is still disconnected.

#### talkin Monkey

##### Well-Known Member
A bandwidth issue? Maybe the twist rate inside the cable is not applicable to how you are using it?

##### Well-Known Member
Consider that message as "Poorly worded". That is the message you get whenever a cable is not connected. Not just that status has changed. It is possible to have one end or the other showing a link if the receive pair on that end is connected. But without both TX and RX it is still disconnected.
Okay, this is starting to make some sense. I never really thought about how it works because I've never had it not work. One pair of wires is send and the other is receive so that I've got one pair working it knows something is there but communication is only in one direction. Do I have that right?

##### Well-Known Member
A bandwidth issue? Maybe the twist rate inside the cable is not applicable to how you are using it?
If so it must be really horrible wire because I've got a cheap Actiontec router that Verizon supplied for free connected to a bottom of the line eMachines computer. Somehow I don't think either of these is pushing the limit.

The wire looks like the right gauge but is it possible that it's drawn thin in places and the voltage drop is too big?

I'm just shooting in the dark. Plumbing is so much easier. When something doesn't work I just look for the puddle.

#### clreynolds

##### Well-Known Member
One pair of wires is send and the other is receive
That is correct. That is also how it is possible to make a crossover cable; connect TX1 to RX2, and RX1 to TX2. Polarity(+/-) must be maintained, so 1 to 3, 2 to 6; 3 to 1, 6 to 2.

One last thought. The twist in the cable are important. CAT5 specs say you cannot untwist more than 1/2 inch at the end of the cable.

Last edited:

#### Trident

##### Retired, plenty of kits
If all else fails, save the cable for use as igniter leads. Last time I made my own igniters with Firefox pyrogens, I used CAT5 pairs. Excellent for small nozzles like 24mm reloads.

Last edited:

#### jbuscaglia

##### Rusty-eyed Missile Man
Plumbing is so much easier. When something doesn't work I just look for the puddle.
Just look for the pile of electrons on the floor. You may need your magnifying glasses, though.

##### Well-Known Member
Just look for the pile of electrons on the floor. You may need your magnifying glasses, though.
The electrons get lost in all the crap on the floor.

#### fxrs

##### Well-Known Member
Consider that message as "Poorly worded". That is the message you get whenever a cable is not connected. Not just that status has changed. It is possible to have one end or the other showing a link if the receive pair on that end is connected. But without both TX and RX it is still disconnected.
Actually, That wording is correct. The computer checks to see if there
is a network cable connected to your ethernet card. If it does not detect
a signal it shows as disconnected. It does not know or care if you had
a cable connected before and now you don't. If there is an ethernet
card active it checks for signal. If the cable you were using had
continuity issues there would be no signal and show up as disconnected.
If you were to take a computer that never had an ethernet card installed
before and you installed one but did not connect the ethernet cable
after boot up it would show up as disconnected.

#### clreynolds

##### Well-Known Member
Actually, That wording is correct. The computer checks to see if there
is a network cable connected to your ethernet card. If it does not detect
a signal it shows as disconnected.
You are correct. I was referring to Bill's question if "Dis"-connected meant that the status had changed, and it was connected at one time. Instead of a message more like "Network cable is not connected".

#### falingtrea

##### Well-Known Member
I woldn't be suprised if the stuff you got from ebay is cat3 or worse. Cat 5 is pretty much a commodity item now. I have bought 100' bulk cat 5e (which is even higher quality than cat5) at Lowes for like $8-$10. I don't think much cat3 is being sold nowadays. And Cat 5 is pretty much being used for phone line installations in new building.

Also, that cable could be a cheap cat5 knockoff that has all of the twisted pairs twisted at the same rate. Quality Cat 5 cable has slightly different twists for each pair, to reduce crosstalk.

Last edited:

##### Well-Known Member
Here's what the wire says on it:

NETCONNECT CATEGORY 5e CABLE E138034 1300 24AWG FTP CM/MP (UL) C(UL) CMG/MPG VERIFIET TO CATEGORY 5 12952FT

The only Google hit I get for Netconnect and wire is AMP Netconnect and I'll bet they know how to spell "verified".

#### Swampworks

##### Well-Known Member
I'm not saying I understand the CAT5 wiring, but here's my story:

Just moved into a different office here at work. Connected my PC and could not get a net connection. They tested the network outlet and test showed fine so they said it must be my cord (wall to PC). Maybe a bad cord so I grabbed the old cord from the previous office that worked. Same result, no connection. Tech guy tells me that sometimes cords go bad......It worked 30 minutes before. Anyway, he goes to get a new cord and I ask if I can keep the old ones since they would be trashed (I'm thinking igniters). New cord works fine. When I get home, I get a weird idea to try the cords on the home network......BOTH work fine! So, just to create more confusion, I take the cord back to work the next day and connect them in the old office again and guess what....Both work there, but they still wont work in the new office. I don't understand, but I reported it to the tech guys....They never gave me any kind of explanation though and now I have 37' of wire for igniters.