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I attach a USB device to the Mac, which I otherwise know is quite power hungry (eats more than 200 mA @ 9V). So I plug this in the Mac (OSX 10.5.8), and get a:

USB Over Current Notice.

A USB device is currently drawing too much power.
The hub it is attached to will be deactivated.

Good enough – it is almost something I had expected..

So I add external power to the device, and I try to plug it in again - and Mac OSX doesn't react. Again, as expected, since the dialog said: "The hub it is attached to will be deactivated".

However, now it seems that I'd have to reboot the Mac from the start, to test this device's connection now that it has external power. And of course, I would like to avoid restarting, so my question is – is there a software way, for me to "reset"/"stop" this "overcurrent protection", and bring the USB port it is connected to again in the normal/default/activated state?

EDIT: Now I tried plugging it a few times more - without restarting - and strangely, it started working... What I did was tail -f /var/log/system.log, and then could see USB related messages realtime.. So maybe to redefine my question - is there a (default) way to monitor and check, whether the USB overcurrent protection is active for a given port/hub?

  • What exactly are you plugging in that is 9V? USB is only 5V. – James P Sep 8 '11 at 11:47
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    Why are people so against restarting? – Ramhound Sep 8 '11 at 11:53
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    @Ramhound; Sometimes you can't reboot, knowing how to do things the right way, rather than the easy way, is important too – Phoshi Sep 8 '11 at 12:13
  • @James - it's an Arduino with a custom analog preamplifier shield, powered by 9V (the 200 mA, I measured from output of this source - I didn't intend to refer to USB's 5V, sorry about the misunderstanding) – sdaau Sep 8 '11 at 12:55
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    @Ramhound - in this case, I have to start up and monitor several scripts manually (they don't lend themselves being called from a single script), which takes some time, which I'd like to avoid losing. – sdaau Sep 8 '11 at 12:55

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