Re: USB 2 or 1

On Tue, 27 Mar 2007 M.I.5¾ wrote:


"thoss" <usenet@xxxxxxxxxxxxxx> wrote in message
news:7xKAMuARdQCGFwWD@xxxxxxxxxxxxxxxxx
On Tue, 27 Mar 2007 Martin Underwood wrote:

"thoss" <usenet@xxxxxxxxxxxxxx> wrote in message
news:4P7gTKAXXOCGFw0P@xxxxxxxxxxxxxxxxx
On Tue, 27 Mar 2007 M.I.5¾ wrote:

The one thing that doesoccur to me is that the USB2 port in the disk
enclosure is defective in some way. Does it connect as a USB2 on
another
PC?


No, its behaviour is consistent, on all the USB 2 ports I have: on a
PCI
card and on a cardbus card on a laptop.

Then I err to the view that the High Speed mode port on the disk drive
is
non functional, but the fast mode port is working (like PCs they are
different physical ports, though the switching between them is
transparent
to the user (when they work)).

I'm not sure I follow that. Does a USB 1 gadget (made before the
invention of USB 2) have a High Speed mode port?

No. I think what MI5¾ has said is:

- USB1 sockets on computers and USB1 peripherals each have USB1 ports

- USB2 sockets on computers and USB2 peripherals each have both USB1 ports
and USB2 ports; these auto-switch

When you plug a peripheral into a computer, the USB2 port (if present) on
the peripheral tries to talk to the USB2 port (if present) on the
computer.
If a USB2-to-USB2 connection cannot be made (either because peripheral or
computer is USB1 or because USB2 port is not working) then the devices
negotiate USB1 instead.

Yes, I understand that. But in that case what is happening with my
drive (USB 2) when plugged into a USB 2 port would seem to be that a USB
2 connection fails, they try to negotiate a USB 1 connection but that
also fails; whereas connection between a computer USB 1 port and the
drive succeeds.


I believe that your USB2 port on your drive is faulty*, but not to the
extent that windows believes that a connection has failed. Thus it
maintains a USB2 connection even though Windows cannot persuade it to
actually talk. When you connect it to a USB1 port, there is no attempt to
enumerate USB2 mode, so USB1 happily chats away (the mesage about it being
quicker on a USB2 port pops up because windows recognises the presence of a
USB2 port).

Linux handles the USB2 connection a slightly different way. It will
certainly be a different driver and, being open source, most probably
better, more robust and more tolerant of errors.

*or may not conform to the USB2 spec, but others would have had similar
complaints. It might be a slightly out of spec chip that slipped through.



Yes, that makes sense - well, almost. You state elsewhere that they
connect on USB 1 first, then USB 2 if present. So presumably they would
connect on USB 1, switch to 2 since USB 2 is present at both ends, but
not have the wit to switch back to USB 1 when they find they can no
longer communicate.

Sometimes I find the intricacies of computing baffling. What a
wonderful thing is usenet, where we have experts like you, M.I.5¾, with
your expertise and infinite patience to explain things to us simpletons.
Many thanks.


Now, to go back to the beginning: I first mentioned my errant USB drive
in response to Ed Cryer's plea for some way to tell which of his USB
ports is 1 or 2. So far as I know, the only way to do this - apart from
measuring actual data transfer rates - is to acquire a drive with
precisely the fault mine suffers from.

Come to think of it, maybe my drive is unique and valuable. Worth its
weight in gold? I'm open to offers.
--
Thoss
.

Relevant Pages

  • Re: HPDeskJet 812C printer, can I make 2 direct connections with parallel & USB?
    ... parallel connection and a USB connection. ... and hook up the Vista comuter to the USB ... parallel and USB ports can usually use only one port at a time. ...
    (comp.sys.hp.hardware)
  • Re: HPDeskJet 812C printer, can I make 2 direct connections with parallel & USB?
    ... parallel connection and a USB connection. ... and hook up the Vista comuter to the USB ... parallel and USB ports can usually use only one port at a time. ...
    (comp.sys.hp.hardware)
  • Re: Its about what users want, stupid.
    ... truly) who walks into an Apple Store and picks up a MacBook Air is going ... EV-DO 3G card in favor of an annoying USB model. ... Unless there is a port on a thunderbolt display for wired ... but that Enterprise-based Ethernet connection doesn't benefit ...
    (comp.sys.mac.advocacy)
  • Re: Vs2005 to PDA to Rs232 interface
    ... I realize comparing the Dell x51v to our pcb is apples to oranges but it ... Rs232 and Usb connections) is not due to ... requires that the Dell device have a *host* USB port, ... Assuming there is a device out there that will take a Usb connection ...
    (microsoft.public.dotnet.framework.compactframework)
  • Re: LENOVO USB-1 or 2???
    ... It might have only had USB 1 ports. ... The error message described comes from the EHCI port ... USB2 or has become damaged in some way. ...
    (comp.sys.laptops)