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How do I get Windows Vista or Windows 7 to re-attach a USB device without having to plug it in again?

For example, after ejecting the USB drive, I would like to inject it again.

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I could do this by physically removing the USB, and re-plugging it in again. But I was wondering since the USB is already plugged in, isn't there someway to do this without having to physically re-plug the device into the laptop?

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marked as duplicate by techie007, Siim K, Simon Sheehan, HackToHell, Dave Rook Dec 17 '12 at 11:33

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2 Answers

up vote 4 down vote accepted

The answer is that there is no nice way to do that.

It's because of the way USB standard was designed. Basically when device is plugged in, it is enumerated and then it can be used by the system. A USB device (for USB less than 3.0) itself can't initiate communication with the system on its own, so it relies on the system to initiate communication with it first. So when you safely remove a device it loses its enumeration and since the device can't communicate any more with the system, system doesn't know it's there. The only way to solve this is to reset the USB hub which will in turn reset all devices connected to it.

USB 3.0 devices should be able to initiate communication on their own, so maybe we'll have flash drives that can remount themselves after being safely removed.

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How do we "reset the USB hub" in software? –  Pacerier Oct 5 '11 at 5:24
    
For Windows look here, for Mac OS look here. I can't find a question about GNU/Linux distributions, but there's a way to to it there too as well as on BSDs. –  AndrejaKo Oct 5 '11 at 5:38
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You can use the devcon utility to remove the usb drive once unmounted, but only under certain circumstances:

devcon remove USB\VID_xxxx*PID_yyyy*

You can find the vid and pid in device manager for the device

Then do a rescan:

devcon rescan

This is best explained by Uwe. Uwe suggests putting a hub between the storage device and the PC. Then eject the usb storage device, then devcon remove the hub, then devcon rescan to pick up the hub again. This should then reactivate the storage devices on the hub.

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But internal ports are connected via hubs too, so there's no reason why to use a separate external hub unless the internal one happens to be connected to some other device which is critical to system operation. –  AndrejaKo Oct 5 '11 at 7:54
    
Yeah good point. –  Paul Oct 5 '11 at 11:35
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