Help on USB 2.0 cable length


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canturn

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Sep 29, 2002
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#1
Looking at a longer USB 2.0 cable for tenthered shot to from my Canon 5D to my Powermac G4 as the one supplied by Canon is really damn short....

What's the max recommended length I should go for when it comes to USB 2.0 cable for that purpose? Thanks in advance!
 

user12343

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May 15, 2005
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#2
tink the specs say not to exceed anything more than 5m between data equipment.
 

Witness

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Mar 18, 2004
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#3
eh...for my camera...it uses a firewire instead...but i got a 3m...i tink one of my friend uses a 5m usb cable for his camera...
 

antere

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#4
From my understanding. Max length for USB cables is 5m. Anything more, you might have to use a 'repeater' kind of device to go further distances.
 

jeremyftk

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Jun 24, 2005
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#5
antere said:
From my understanding. Max length for USB cables is 5m. Anything more, you might have to use a 'repeater' kind of device to go further distances.
Correct. That's what I plan to do soon... ;)
 

canturn

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#6
Friend of mine bought a 5meter USB cable, comp couldn't recognise the camera.

I thought repeater is for Firewire only?

Sigh...these long cables /repeaters can cost like 70+
 

#7
canturn said:
Friend of mine bought a 5meter USB cable, comp couldn't recognise the camera.

I thought repeater is for Firewire only?

Sigh...these long cables /repeaters can cost like 70+
in fact you can have repeater for all digital communication stuff :) if the USB specs says the max length is 5m yet the 5m usb cable doesn't work for your friend, most probably the quality of that usb cable is no good.
 

user12343

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May 15, 2005
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#8
found from the USB developer webby: http://www.usb.org/developers/usbfaq/#cab2

Q. I want to build a cable longer than 5 meters, why won't this work?

A: Even if you violated the spec, it literally wouldn't get you very far. Assuming worst-case delay times, a full speed device at the bottom of 5 hubs and cables has a timeout margin of 280ps. Reducing this margin to 0ps would only give you an extra 5cm, which is hardly worth the trouble.

Q. What about using USB signal repeaters to make a cable longer than 5 meters?

A: Don't bother. The best solution is self-powered hub with a fixed 10m cable that had a one-port bus powered hub in the middle. The maximum range will still have to deal with the timeout, so any out of spec tweaking of the terminations between the two hubs and the timing budget still won't yield more than 5cm of extra distance. A better solution is described in the following question.

Q. I really need to put a USB device more than 30 meters away from my PC. What should I do?

A: Build a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. Use a long-haul signaling protocol like Ethernet or RS-485 in the middle. Using cables or short-haul fiber, you can get ranges upwards of a kilometer, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.
Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge.
 

Aug 11, 2003
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#9
i shoot up to a length of 7 meters using usb 2.0 , tethered on c1 pro to my pbook. No problems whatsoever at all. Image download is 1/2 sec for a full 8 MP file.
 

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