Re: xD transfer speed through printer to computer

ASAAR wrote:

I once had an HP driver causing a similar drastic transfer
slowdown. It occurred 5 or 6 years ago when I attached a CF card reader
that used a parallel port. Prints that should have taken a minute or
two at the most were taking nearly an hour. The problem was solved when
an HP technician explained how to reinstall the HP print driver using a
hidden menu that disabled the printer's bidirectional data transfer. The
printing slowdown was now eliminated, and the only loss was that I
couldn't use the computer to monitor the status of the printers ink
cartridges.

Heh, that is weired. I would have thought you needed bi-di to use the
cartridge ink level monitoring function.

I wonder what kind of results you'd get if you (temporarily) disconnect
the HP2575 and replace it with a cheap card reader? This wouldn't
necessarily help, and could worsen the problem if the driver isn't smart
enough to stop trying to read the HP's status data. But if that gives
you fast transfers you might want to reconnect the HP2575 and attach the
card reader to your USB 1.1 hub. It wouldn't transfer files quite as
fast as if it was USB 2.0 High Speed, but your 1 minute transfers would
probably drop to only a second or two per file.

I've found a workaround that is adequate until I get around to upgrading
my OS. Boot to Knoppix (a Linux Live CD) and plug in a card reader. Reads
and transfers 30 1.4 MB photos in seconds.

Another cause of the problem may be that the HP's driver is
stupid, not optimized for when it is just the central point in a file
transfer between its USB and ethernet ports. It may not be adequately
buffering large numbers of data blocks, before trying to send them. For
instance, if it reads a 512 byte block (I seem to recall ethernet
packets ranging from about that 386 bytes to 2k or so) and won't read
another until it has successfully transmitted that block, it could slow
down the transfer rate tremendously even if no other device is active on
that ethernet cable.

That's a possibility I hadn't considered. A quick Google found this
article from Novel that shows the relation to packet size versus
throughput in ethernet (and other) networks.

http://support.novell.com/techcenter/articles/ana19960103.html

--
Tony Sivori

.

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