Network cable locator.

[levonbragg]

Anyone have any ideas on how to make a network cable locator that will work when a cable is plugged into a switch. Something that can flash a specific pattern on the activity light? I tried googling it, but my google-fu is failing me...

Thanks.


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[artag]

The network cable checkers that I've come across don't do this. They expect you to put a tester at each end and look for a result. If you've only got a few wires, then you could put a slave checker on a remote end, then plug each 'switch' end of the cables in turn into the master end and look for a result. Move the slave end to the next wall outlet and repeat until all are identified.

This is a bit slow and isn't so good if it's a working network. You'll have to interrupt all the working circuits to check them.

In that case, you could record all the switch lights that indicate a circuit is connected (not active, just connected. Some switches don't show this but most do). Then go to your remote end and connect a laptop. Go back to the switch and record all the connection lights again. If you're lucky, only one has changed and it's yours. If more than one has changed, repeat until you can narrow it down.

You could perhaps build a device that sends lots of packets, goes quiet for a while, the repeats. Look for the flashing activity light. But this is hard to do genericly - the switch might have lots of other flashing lights that are hard to ignore, you need to send a packet that will brighten the activity light yet not get re-broadcast to other outlets (which might make them light up too) and, worst of all, the switch probably doesn't directly show the activity : it turns a light on when a packet is received, and off a bit later. Send too fast and the switch will just leave the light on permanently, or blink it in some pattern of it's own.

[commongrounder]

I have a small network cable tester from Test-um/JDSU that will flash a router or switch at the other end.  There must be others that will do that, too.

[CaptainObvious]

I bought this and it's the best money I've ever spent for finding cables and where they're located on patch panels. Well worth the money, but obviously SUPER easy to reverse engineer these.

http://cablesupply.com/wire-labeling/443-combo-power-pack-for-cable-identifier.html


EDIT:  To add some.. more pertaining to the regular post, this would be a fairly easy project for an Arduino with an Ethernet shield, you can pick them both up for $20 total, then just make a small program that would burst data at set times, for example, basically blink the LED on the switch every 1 second, very steady so it's obvious to pick up. The Raspberry Pi is a good choice too, depending which poison you prefer.

[donkey77]

Not quite what you are after regarding using the switch activity lights and maybe too expensive for your needs but worth a look anyway.

http://www.peakelec.co.uk/acatalog/jz_utp05.html

[Fungus]

EDIT:  To add some.. more pertaining to the regular post, this would be a fairly easy project for an Arduino with an Ethernet shield, you can pick them both up for $20 total, then just make a small program that would burst data at set times, for example, basically blink the LED on the switch every 1 second, very steady so it's obvious to pick up.

I would do S.O.S or something like that... 

[PaulAm]

When I was running network cabling I had a 'fox and hounds' gadget.  You plugged one piece into one end and there was a non-contact sensor that you waved around the other end until you heard the tone.  The point that you didn't have to make actual contact with the sensor made it pretty quick.

The current iteration of that is the Ideal 33-864

I haven't played with the Arduino ethernet adapters, but assuming you can turn them on and off under program control, it wouldn't be difficult to cobble together something that would flash a hub light in a pattern.  Heck, you could just power the adapter from a driver managed by the arduino and turn it on and off in whatever pattern you wanted.  The lights indicate link status; you don't even need to configure the interface.

[Cliff Matthews]

Anyone have any ideas on how to make a network cable locator that will work when a cable is plugged into a switch.

I've had a couple of these cheapo toner/probe sets for like 20 years.
http://www.ebay.com/itm/Tempo-Progressive-Electronics-200EP-Inductive-Amplifier-77HP-Tracer-2-/191591893933

If you use a good battery in the toner, you should be able to audio-trace cables very well. I've found a solution at times is to send the toner's signal down the unused pins 7 and 8 (the wt/br pair) or pins 4 and 5 if you have too. You could hear hum and other artifacts on that pair since some jacks could be pre-wired to an ungrounded 48v line from a PBX or other confabulated equipment.

As for verification of other end being plugged into a switch, you can switch to continuity-mode and clip on to pins 1 and 2 (wt/og pair) and then pins 3 and 6 (wt/gr pair) and look at the led. A hub or a switch will have a termination ~50 ohms, which is typically enough to turn the light on.

It is good to remember when audio tracing that the comms equipment presents a low impedance (~50ohms) that a weaker battery doesn't cut through so well. So the closer you get to the switch the weaker the sound will be from the probe's speaker. Some inductive probes have 2 pins you can clip an powered "butt-set" phone on to, so you can hear the weak audio (and the warble sound will not disturb the tranquility of office workers..).

Youtube "toner inductive probe" and see a variety of methods there - above all, have fun!

[levonbragg]

Thanks for all the suggestions. I think I'll try a few with the arduino. I have a few Ethernet shields laying around.


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