[PLUG] Scanner dependent on USB port [RESOLVED]

tomas.kuchta.lists at gmail.com tomas.kuchta.lists at gmail.com
Mon Feb 3 01:47:18 UTC 2020


On Sun, 2020-02-02 at 13:32 -0800, John Jason Jordan wrote:
> On Sun, 2 Feb 2020 13:11:28 -0800 (PST)
> Rich Shepard <rshepard at appl-ecosys.com> dijo:
> 
> > I should have known that USB ports have limited power supply
> > capabilities. My external optical drive (used for the Dell 2100 and
> > ThinkPad X200) has two USB cables, one for power the other for data.
> 
> I also have an optical drive that came with a cable like that. I could
> never figure out which fork was data and which was power, and then I
> wondered if it was using both for power.
> 
> It was advertised as being USB 2.0. The interesting part is what happens
> when I plug it into a USB 3.0 port. (None of my computers have USB 2.0
> ports any more.) Not only does the drive not need both forks inserted,
> it also doesn't seem to matter which one I use.

On the contrary - all of your ports are usb3 and also usb2 - it is part of the
compatibility spec for the root device to have both 2 and 3 controllers hanging
on the USB-A connectors.

For hubs - that may be different - although after brief period when usb3 was new
- most likely all hubs are 2 and 3 these days.

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