USB - multiple conn...
 

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[Closed] USB - multiple connections "just work" don't they ? Speculation welcomed

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Let's imagine a laptop with one single USB socket (as worst case scenario)

Would it work if I wanted to attach, simultaneously:
USB keyboard
USB mouse
USB DVD drive

is a 3-scoket hub all that's needed - when do you need a powered hub ?

On the tiny chance that it didn't have an ethernet socket, would a USB-ethernet cable also work


 
Posted : 29/11/2015 5:56 pm
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You'll need a powered hub for the DVD drive


 
Posted : 29/11/2015 6:29 pm
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really hammy?

The drive itself is has a power supply; do I still have to power the hub?

thanks


 
Posted : 29/11/2015 6:45 pm
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You didn't put that in the OP Scaredy - in that case no.


 
Posted : 29/11/2015 6:58 pm
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The drive itself is has a power supply; do I still have to power the hub?

Then probably not, but... it would be wise to get one anyway - you don't need to have it powered on all the time, but the facility would be there in the future when you need, for example, to connect a 2.5" external drive./something else which needs power.


 
Posted : 29/11/2015 7:01 pm
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OK, I'll look at powered hubs, ta

But in principle the multiple USB "feeds" can all go through one port on the PC ?


 
Posted : 29/11/2015 7:16 pm
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Yes. Each USB device has its own address. That's the whole purpose of a hub. The only restriction is power*, as one USB port is only allowed to supply a certain number of amps, which is why you need a powered hub if you have devices that need that exceed that limit.

*(well there is some loss of throughput too but that's only an issue if you start putting multiple high speed devices on the one hub).


 
Posted : 29/11/2015 9:05 pm
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The only restriction is power

That's not strictly true, though it is true for pretty much all practical purposes. A USB host supports 128 devices (including itself).

You need sufficient power to drive whatever devices you attach, and an individual (USB2) port can supply 500mA. Power requirements will be device-specific, so if demand is greater than supply you'll need to add an external power source. For a keyboard, mouse and something that's already powered, I wouldn't worry about it.


 
Posted : 29/11/2015 10:03 pm
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The new Dell docking station plugs into the usb3,does ethernet, screen and USB. I'd still rather have then separate though


 
Posted : 29/11/2015 11:22 pm