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Build USB Long Cable

Discussion in 'Electronic Basics' started by [email protected], May 27, 2007.

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  1. Guest

    if I build by my self a USB cable by 4 seperate coaxial cable
    together , it's can work over 5 meter?
     
  2. Jamie

    Jamie Guest

    if you have low capacitance how ever, I would make a buffer
    driver system to beef up the current.
    They use to make these things call Black Boxes for RS-232
    runs. they were nothing more than twisted balanced input and
    outputs which gives you lots length to work with.

    actually, I think products already exist for that.
     

  3. USB is NOTHING like RS232 in its cabling requirements.


    There are two conductors for data, power and ground. There are USB
    extenders on the market when you need a longer line. You run into timing
    errors with long cables, without using an extender. It is a
    bi-directional communications device that regenerates the USB signals.

    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  4. Jamie

    Jamie Guest

    Yes, I am aware of this, so isn't the RS-232 as 2 conductors RX and TX
    for data streams how ever, that doesn't change the facts that long haul
    units were made implementing twisted pair balanced lines to transport
    between to units and thus back into RS232 again.
    I know this because I have a whole load of these "Black Boxes" and
    they also work with USB, I'm using one to transport
    USB cable on a long haul from a machine to a PC to monitor settings
    in a machine...
    I simply made a conversion plug and used a couple of existing black
    boxes I have in my arsenal.
    These units claim a long distant but the 2 i'm currently using are
    running aprox 3000 Feet to get the signal into the shop.
    They have been working fine with no data problems that i know of..
    on the scope the signal looks good..
    Can't tell you the speed it's operating at because I don't know that..

    P.S.
    we're using FEP cat 5 wire if that makes any difference, since we
    make that kind of wire there, it was just convenient at the time.
     
  5. Eeyore

    Eeyore Guest

    You want a 'balanced RS232' ?

    Use RS485.

    Graham
     
  6. Only two of the lines carry signals, the other two are power, however the
    spec says it won't work. But you can buy extender cables - try two of those
    and see if it works.
     


  7. Go ahead and keep advising people to do things outside of the specs.
    You are obviously smarter than anyone else on Earth, including the
    people who develop the technology and write the standards. Let people
    waste their time tryting to make it work properly, what do you care?



    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  8. Guest

    thanks all, but

    I looking after cheap solution for long cable for long cable for my
    Point devices (USB Keyboard + USB mouse + Touchpad).

    It's posible to achive this target with some trick?
     
  9. Jasen

    Jasen Guest

    5m than you'll need a hub, after that you can have another 5 metres
    (and then another hub if you want to go further).
     
  10. Circa Sun, 27 May 2007 20:59:03 -0400 recorded as
    <dFp6i.2582$> looks like Jamie
    It sounds like what you have is an RS232 to RS422/485 converter. Do you
    have a part number or some other identifying mark for these "black boxes?"
    I'm very interested in finding out how they buffer the input data.
    Your shop is a half-mile from your home? That's a big property you have
    there. Here is the limitation of your setup: cable length vs. data rate.
    The data rate limit of RS422/485 varies with cable length. At 3000', you
    will have 20% jitter (that's a lot) at a data rate of 800kbps. (Nat'l
    Semiconductor Application Note 214, August 1993)

    The USB 1.1 standard has two data rates, 1.5Mbps and 12Mbps. Apparently
    the slowest USB rate exceeds by double the capability of the RS422/485
    standard at that cable length. Commercial USB->RS485 converters I've
    googled don't claim higher than 1Mbps (921.6kbps is a typical maximum).
    I'd also like to find out how these commercial devices handle the data rate
    difference. Anyone?
    If you can see the signal on a scope, then you should be able to calculate
    the data rate. I'd be very interested in knowing what rate you are
    achieving.
    At <1Mbps data rates, cat 3 works fine (rated up to 10Mbps). You should
    get no tangible advantage from using cat 5.
     
  11. Rich Grise

    Rich Grise Guest

    I've used USB cable extenders, but except they had PS-2 mouse-type
    connectors. I got reliable USB over 12', which is close to 4 meters.

    Good Luck!
    Rich
     
  12. Spajky

    Spajky Guest

    Yes :) it can be done :)

    non-powered version:
    http://193.189.160.28/seibert/HP/UsbEnh/UsbLongCable2.gif

    & this I use also for powering a wifi Usb stick at the same time
    http://193.189.160.28/seibert/HP/UsbEnh/UsbLongCable.gif

    This last for example approx.15m long "fast DIY" made with ordinary TV
    coax I used it for my active wifi UsbKey antenna experiments :
    http://193.189.160.28/seibert/HP/UsbEnh/UsbProlAll.jpg
    http://193.189.160.28/seibert/HP/UsbEnh/UsbProlEnds.jpg


    Ps.: if anybody would like to check (pics&data only of) that my 2,4GHz
    active WLAN UsbKey antenna DIY extending range experiments, you can do
    it here (text is in my native language-slovene & not in english, so
    you would not understand it probably, but you could get some clues) :
    http://www.wlan-sat.com/modules.php?name=Forums&file=viewtopic&p=26476#26476
    ... have fun ... :)
     
  13. Your a dumbass. Your the one who actually thinks they are the smartest
    person on Earth and you get pissed when someone doesn't do things your way
    or agree with your methods.
     
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