tester to prove cat5 socket is live

Discussion in 'Home Networking' started by keith dulwich, May 9, 2004.

  1. Is it possible to make a tester to plug into an ethernet cat5 RJ45 socket
    to prove the socket is "live"? (preferably without disrupting the comms of
    everyone else on the LAN)?

    My work typically provides several data jacks in a meeting room, but only a
    few, sometimes none, of them are live & it's not marked.
    So I seem to spend 15 mins every meeting trying to find a live socket. My
    only way to prove it's live is to plug in my laptop and look for the LED's
    on the LAN card to light after it boots. IF not, then shut down laptop & try
    rebooting on another socket.*

    So can i just make a portable tester with a bit of cat5 cable and , say,
    LED's across green and /or orange pairs, so I can find the live socket frst?
    (if so what voltage does ethernet work at so I can calculate the resistor
    Or will this disrupt everyone else on the network & get me in big trouble?


    *The laptop logs in to mail etc. at boot up so I can't just boot up and then
    keep trying sockets as it'll stay working "offine" afterwards.
    keith dulwich, May 9, 2004
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  2. keith dulwich

    Kris Guest


    .... but you really won't like the price - about £500 :)

    I have no experience with it myself, however.
    Kris, May 9, 2004
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  3. keith dulwich

    Lurch Guest

    Good question, I use a Fluke LanCat tester. They're a bit pricey
    though for what you want.
    I would get a proper data installation engineer to do the work for you
    next time, maybe he can label the sockets up as a professional would
    A cheap hub, under a tenner. The link light will come on instantly if
    the socket is live..
    Can you not just set it to work "online" after you've booted up, or
    are logging on to the domain?
    Lurch, May 9, 2004
  4. keith dulwich

    Dr Zoidberg Guest

    Its very common to have a whole bunch of numbered sockets in a room all of
    which run back to a patch panel in the comms room , however not every single
    one will be then patched into a switch. Thats nothing to do with the wiring
    being done incorrectly.


    "We are now up against live, hostile targets"

    "So, if Little Red Riding Hood should show up with a bazooka and a bad
    attitude, I expect you to chin the bitch! "

    Dr Zoidberg, May 9, 2004
  5. keith dulwich

    Lurch Guest

    I know, I am that aforementioned professional installation engineer. I
    never said they should all be live, I said they should all be
    Although now I reread the OP, I realise I may have misinterpreted as
    the points are un-numbered, I realise now that the OP means un-marked
    in the sense of active or not. Oops! ;-)
    Back to the original question, would it not be easy enough to look in
    the cabinet to see which ones are plugged into the switch, or is it
    one of those with randomly coloured cables randomly strewn about the
    Lurch, May 9, 2004
  6. Thanks, I agree it would be more sensible for them to label the sockets to
    show which are live, but that's the just way they do things! I suspect the
    switch ports get reused to save money.
    Wouldn't a small hub still need to be powered up though first? I want to
    minimise the amount of time I waste in rooms without any live points.
    Can anyone confirm if my idea of just making a box that puts LEDs across
    the pairs would work or screw up the LAN?
    keith dulwich, May 9, 2004
  7. keith dulwich

    Lurch Guest

    Yes, but it's just a case of plugging in the power and the LAN cable
    and that's it, no booting up or anything. Instant illumination, or not
    as the case may be! You could even battery power it for testing
    purposes, some of the smaller ones use a 5v adapter or similar.
    Lurch, May 9, 2004
  8. keith dulwich

    Mike Scott Guest

    Don't some places use the same cabling for LAN & phone? What happens
    if these get misconnected -- 50V of ringtone into a LAN input?
    Mike Scott, May 10, 2004
  9. keith dulwich

    Ian Guest

    Its a simple bit of "user training" and a few spare patch leads.
    all you need to do is leave the lead in the working socket and then
    everyone will know its working. This is what we used to do and advised
    customers to do. Or install a WAP in the meeting rooms and a wifi card
    in laptops. otherwise as allready sugested get a microhub for less
    than a tenner.

    Ian, May 10, 2004
  10. keith dulwich

    Ian Guest

    Almost all offices do as do many homes, but Ringing is approx 85v AC
    and it wouldnt damage lan equipment as its on different pairs to the
    lan tx/rx and POE, the pair should be N/C on the lan card.

    Ian, May 10, 2004
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