On Fri, 14 Jul 2006, Randy.Dunlap wrote:
> > Oh dear. Too bad you didn't mention this before.
> >
> > There are limitations on how long a USB cable can be. You may be up
> > against those limits.
>
> Yes, it's 5 meters max between hubs.
It's not quite that simple. Section 6.4.1 of the USB 2.0 specification
("Standard Detachable Cable Assemblies") says:
The maximum allowable cable length is determined by signal pair
attenuation and propagation delay. Refer to Sections 7.1.14 and
7.1.17 for details.
(Unfortunately, 7.1.14 and 7.1.17 are fairly impenetrable to anyone who
isn't an electronics engineer.)
Also, section 6.4.4 ("Prohibited Cable Assemblies") says:
Prohibited cable assemblies may work in some situations, but they
cannot be guaranteed to work in all instances.
Extension cable assembly
A cable assembly that provides a Series A plug with a
series A receptacle or a Series B plug with a Series B
receptacle. This allows multiple cable segments to be
connected together, possibly exceeding the maximum
permissible cable length.
Alan Stern
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