Question Cutting power to USB header while Windows is running?

Dom Portera

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Is it possible to cut power from a USB bus header and re-power it on and have Windows still recognize it? As you can probably assume I'm getting pretty desperate for some solution to turn off power to USB ports without rebooting the PC.
 

Dom Portera

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yes I've seen these things, but there's a difference between enabling/disabling a serial connection vs actually disabling the USB's power output, which the only solution seems to be literally severing power from the port

one of those looked promising but it seems to be a way to disable things as if you were disabling it in the device manager - we've tried this manually and it didn't solve our problem
 

Karadjgne

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Windows won't touch usb power, that's a bios priority. Usb data is different, as far as enable/disable the ports goes. Need to have that 5v present in order for the port to be recognised for windows timers, wakeup, handshake etc when you plug something in.
 

Dom Portera

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makes sense to me, I figured as much. which is why I'm wondering if I were to disconnect and reconnect that USB power through a relay or other means of electrical disconnection, would Windows be able to recognize it as being reconnected while it's running? or would that just require a system restart anyway?
 

USAFRet

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makes sense to me, I figured as much. which is why I'm wondering if I were to disconnect and reconnect that USB power through a relay or other means of electrical disconnection, would Windows be able to recognize it as being reconnected while it's running? or would that just require a system restart anyway?
Given a powered USB hub, when you turn it on, Windows recognizes it.
Turn it off, no longer recognized.

So it would seem no matter how you power on/off...windows will see it or not.
 

Dom Portera

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I hope so, given that this would be severing power straight from the connection to the motherboard I think it'd be a little different, but hopefully not!
 

Karadjgne

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Simply unplugging/replugging the usb anywhere solves the issue, forces a new handshake without playing around with reboot. The issue is anything automated. You aren't getting power cuts unless you add in something like a raspberry pi powered switch inline, and use that as a terminal disconnect. Lot of work/expense for a simple grab and pull.
 

Dom Portera

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yes i know that does, but i can't unplug/replug in this long-term installation. i know the issue isnt anything automated - my question has been about adding in a power switch between the motherboard and the USB bus and how Windows would react to that, I would end up automating that solution myself if Windows would recognize an unpowered and then re-powered USB bus
 
yes i know that does, but i can't unplug/replug in this long-term installation. i know the issue isnt anything automated - my question has been about adding in a power switch between the motherboard and the USB bus and how Windows would react to that, I would end up automating that solution myself if Windows would recognize an unpowered and then re-powered USB bus
Assuming this is going to a Type-A port, isolate the 5V line from it, run it through a solid-state relay, then have something else controlling the input to the relay.

That's a 1,000 foot over view of how you could go about this.
 
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Dom Portera

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agreed, thats what i wanna do. at the whim of Windows for whether or not it will agree with the method though. i'll test just by unplugging and re-plugging my desktop USBs when i get home
 

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