[filmscanners] Re: Vuescan and 64bit Windows - Ed's reply

["Charles Knox" <cknox@netspace.net.au>]

Not trying to start an argument here (this post is getting too long
already, plus it's really gone off subject), but I still stand by what I
said -- self-powered devices will typically run from a non-powered USB port.

Case in point: My current machine has 4 USB-2 ports on the backplane, into
which are plugged an infra-red detector for a remote control, a Wacom
tablet, a printer and a scanner.

One pair of ports has a fault (dry joint, which one fine day I'll fix --
requires a major strip down...) resulting in no voltage on the power line
-- the tablet and IR device, which are both unpowered, will NOT run off it
(the tablet doesn't react and its LED doesn't light, the IR unit also
doesn't respond) but work perfectly off the good one -- the printer and
scanner (both Epsons) run fine off any one of them, plus all other USB
devices I possess (camera, several flash drives, 7-in-1 reader, wireless
LAN stick) will all work from the 4 matching front ports, but only the
(self-powered) camera will work from the faulty port.

At 10:12 PM 3/06/2006 -0500, Laurie Solomon wrote:
>> My 2c cents here: USB printers, scanners and other
>> peripherals that plug into the wall or are battery-powered
>> typically don't draw power from the USB port so are not affected by
>> the 500mA limit.
>
>Unfortunately, this is not true.  The power that is drawn from the USB
>connection has nothing to do with the power drawn from the wall to power
>or run the device per se.  Power drawn from the USB port is used to
>overcome resistance in the cabling and power the transmission of data
>down the cable - not to power the device.  Powered hubs are active hubs
>that get power from a transformer source that plugs into the wall but
>uses this power to replenishing the USB cable line power that is lost to
>resistance or too many devices making power demands on the hub for their
>cabling and data transmission.
>
>> The 7-in-1 card reader may be marginal in its power
>> requirement, and some motherboards are less robust than
>> others in this department (some can comfortably handle up to
>> 800mA, some struggle with 500, some even vary from one port
>> to another)
>
>On these points, I concur.
>
>----Original Message----
>From: filmscanners_owner@halftone.co.uk
>[mailto:filmscanners_owner@halftone.co.uk] On Behalf Of Charles Knox
>Sent: Saturday, June 03, 2006 8:15 PM
>To: laurie@advancenet.net
>Subject: [filmscanners] Re: Vuescan and 64bit Windows - Ed's reply
>
>> My 2c cents here: USB printers, scanners and other
>> peripherals that plug into the wall or are battery-powered
>> typically don't draw power from the USB port so are not affected by
>> the 500mA limit.
>>
>> The 7-in-1 card reader may be marginal in its power
>> requirement, and some motherboards are less robust than
>> others in this department (some can comfortably handle up to
>> 800mA, some struggle with 500, some even vary from one port
>> to another) -- I suppose you've tried it in other ports?
>>
>> How does it perform with a flash drive?
>>
>> For best results with USB you do need to be running XP SP1 or
>> SP2 -- there's a patch on M$ updates somewhere for the original
>> verion of XP.
>>
>> Charles
>>
>> Jim wrote:
>>> I have three devices plus a seven-and-one card reader, all connected
>>> to onboard USB ports.  My trackball, an Epson 1640 scanner and R2400
>>> printer work fine but the card reader fails to se the Compact Flash
>>> card when it's inserted and a reboot is required - much like my older
>>> machine, running win 2K did when I turned on my scanner.
>>>
>>> Jim
>>>
>>> Laurie Solomon wrote:
>>>
>>>> If you have connected the devices to an unpowered hub, this can
>>>> create problems - especially if you have several devices that have
>>>> power requirements connected to the same hub directly or daisy
>>>> chained to it. Furthermore, despite the claims, two many devices
>>>> and/or hubs daisy chained of the same USB port as well as very long
>>>> cable runs can cause problems as well.  The motherboard bus can
>>>> only supply so much power to each of the USB ports.  The 120 plus
>>>> devices that they say can be connected typically are either low
>>>> power or non-power consuming devices (like mice and keyboards); or
>>>> they need to have an external power source such as an active
>>>> powered hub or a directly powered transformer source.
>>>>
>>>> Like SCSI devices, sometimes USB devices do not get along with other
>>>> USB devices and do not share ports or daisy chains nicely. This can
>>>> cause the OS to fail to recognize the device on a plug and play
>>>> basis, requiring one to have to either reboot or to disconnect and
>>>> reconnect the device or to turn off the power to the device and
>>>> then turn it back on for the system to recognize it.
>>>>
>>>> ----Original Message----
>>>> From: filmscanners_owner@halftone.co.uk
>>>> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of James L.
>>>> Sims Sent: Saturday, June 03, 2006 11:31 AM
>>>> To: laurie@advancenet.net
>>>> Subject: [filmscanners] Re: Vuescan and 64bit Windows - Ed's reply
>>>>
>>>>
>>>>
>>>>> These are USB devices, Tony.  I was told by a so-called computer
>>>>> guru that this problem was corrected in XP.  It could be that the
>>>>> device is incorrectly installed - it's a USB 2 device but its
>>>>> speed, or slowness, indicated that Win XP thinks it an early USB
>>>>> device.  I've tried uninstalling the USB controllers reinstalling
>>>>> them but to no avail.
>>>>>
>>>>> Jim
>>>>>
>>>>> Tony Sleep wrote:
>>>>>
>>>>>
>>>>>
>>>>>> On 02/06/2006 James L. Sims wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> I have a 32-bit device on a
>>>>>>> computer running Windows XP 32-bit that regularly fails to see
>>>>>>> one device unless it's activated and the computer restarted -
>>>>>>> much like the behavior that I experienced with Win 2K.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> That's normal and correct behaviour for SCSI. You can go into
>>>>>> device manager and refresh the view instead, and it should be
>>>>>> seen. Once seen, you can turn the device off and on at will, and
>>>>>> won't have that problem again - until you reboot with the device
>>>>>> powered off.
>>>>>>
>>>>>> Tony Sleep

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