Why do some apps misbehave when connected to a USB HUB

Posted on 2007-08-03
Medium Priority
Last Modified: 2013-11-05
I have found that some apps misbehave when plugged into a port in a HUB.  Plugging a misbehaving app directly into a USB port results in it behaving correctly.

Is this common?  Is there a way to know, without trail and error, to know what sort of apps this will happen with?
Question by:mikecox_
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Expert Comment

ID: 19629911
If the Hub is not powered, adding multiple devices to the hub can cause the power draw to be insufficient for all the devices connected. Self powered hubs would eliminate this problem.

Author Comment

ID: 19629990
I only had two apps plugged into my 4 port HUB.

The last time I experienced this problem I had an external drive plugged into the HUB.  It was working fine and continued to work properly, as far as I could tell,  when I plugged in my printer.  

When the printer was plugged into the other port a document would print but during the process I would get 2 consecutive "doc failed to print" errors and the print cue showed: "error", but cleared when the doc finished printing.  When I plugged the  printer directly into a USB port all that stopped.

Could that be a power supply issue; with two free ports?

Expert Comment

ID: 19649615
When chaining USB devices, the chain should have a powered device every other link. So unpowered, powered, unpowered, powered, and so on. If the power draw is low enough you can squeek by, but it's not a good idea.

Author Comment

ID: 19650151
Well, once again I question that theory; and would like to get a second opinion on it.

It seems to me like most of the multi-port HUBs I see in catalogs and on-line stores are non-powered.  If using them consistently creates the kind of problems I have experienced then why are so many of them being manufactured and sold?  Why have I not seen far more powered multi-port HUBs than non-powered HUBs?  

I just don't understand why manufacturers would develop non-powered, multi-port USB HUBs that are guaranteed to fail with more than one device plugged into them?  

Accepted Solution

djmounce553 earned 750 total points
ID: 19712250
They aren't guaranteed to fail if more than one device is in them, just if those devices are pulling more power than the hub is able to supply via one usb.

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