HI-SPEED USB Device Plugged into non-HI-SPEED USB Hub

C

CWatters

The higher speed of USB 2.0 should in theory mean that a better quality
cable is required but otherwise many web sites say they are the same...

http://www.gainbery.com/faq.htm

What are the differences between USB 2.0 and USB 1.1?
Basically, USB 2.0 includes everything that USB 1.1 offers and adds a
high-speed mode, which runs at 480Mbps. USB 1.1 supports two speed modes:
1.5 and 12Mbps whereas USB 2.0 has three of them: 1.5, 12 and 480Mbps. USB
2.0 also uses the same USB 1.1 compliant cables to connect high-speed
devices. However, classic USB hubs will slow down USB 2.0 devices. In
addition, a USB 2.0 host controller is required to enable the high-speed
connection with a USB 2.0 device.


http://www.silicom.co.il/susb2.htm

In fact, USB 2.0 uses the same cables and connectors as USB 1.1.

etc..
 
C

CWatters

I bet I know what's happening....

I suspect that your scanner was _trying_ to connect at 480 MHz and failing
because of the poor quality cable. Then it was dropping back to USB 1.1 bit
rates and succeeding hence the host thinking it's a USB 1.1 device.

Replace cable with better quality and bingo 480 MHz works.
 
C

Chris

Well, the error started again, so apparently it is not the cable...I do not
know where to go from here!
 
C

CWatters

I notice that some of the web pages I saw for that scanner on the web says
"High speed USB (compatible with USB 2.0). That's not quite the same thing
as "USB 2.0 compliant" or "USB 2.0 certified". I wonder if they had problems
getting it to meet the specs and certified? It does begin to sound like a
hardware problem.
 
D

Dave

As I read it, there isn't a difference between USB 1.1 and USB 2.0 cables.
If they meet the standards they should work fine for both.
 
C

Chris

6.5 ft - 2 meters


Doron Holan said:
how long is the cable? USB has a 6 foot limit distance from hub to device

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had
Click to expand...
 
W

W. Schmidt

Hi, what is a USB 2.0 cable? Supposed to be all the same. Unless you have to
use a better cable.
 

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