I may be stompping over old material here.... (Please link relevant info if necessary, as did not find...)
Was wondering if it is possible (sufficient ampacity, signal issues, etc.) to run a 4 port USB hub upstream from a 7 port USB hub? (If the 4 port need be externally powered to make this work, please let me know).

thanks

 

If I get the question right you want to plug in the 4 port hub into a 7 port hub?
From Wikipedia: "The USB specification requires that bus-powered hubs may not be connected in series to other bus-powered hubs."

So question is, is your 7 port hub self-powered or bus-powered. If it's bus-powered depending on what you connect you will soon run into problems, as the bus won't be able to supply more than 500mA (in general).

With bus-powered hubs I often had already problems connecting only three devices to it.

http://en.wikipedia.org/wiki/USB_hub

 

Both the 7 port, and 4 port hubs would be externally powered.
The 7 port at 3.5A, and the 4 port at 2A (Industrial DIN rail units).

So the downstream power drain issue would not be a problem.
My main concern in correct, consistant communication. (AKA, will the downstream hub maintain it's devices' IDs through the 7 port, or will this become a nightmare?)

Expanding on this note, could there be several externally powered 4 port hubs downstream of said 7 port? And would they remain reliable?
Routing this way would allow use of the server's limited USB ports (2), and reduce downstream wiring clutter and conduit size requirements.

 

Nevermind...Sorry for space wasting... Found out what I needed to know.