USB2.0 - any use for consumer devices

[Martin Trautmann]

Hi all,

is there actually any use for USB 2.0?

I guess that my Microtek ScanMaker 5800 - clone is not a real reference:
it's just painful slow at higher resolutions.


However, I wonder: is it the scanner itself or is there any speed
blocker within the drivers that slows down the scanners that much?

I was told there might be any kind of copyleft agreement in order to
slow down those consumer devices!?

- Martin

 

[Dances With Crows]

is there actually any use for USB 2.0?

Theoretical max data rate for USB 2 is 480 Mbit/second, much higher than
the theoretical max data rate for USB 1, which is 12 Mbit/second. Real
world transfer rates are always going to be lower, of course, but 480 is
much bigger than 12. I have reports of USB 2 Mass Storage devices
sustaining 17 Mbyte/second, which is far greater than the 800
Kbyte/second I usually get from USB 1 storage devices.

I guess that my Microtek ScanMaker 5800 - clone is not a real
reference: it's just painful slow at higher resolutions. However, I
wonder: is it the scanner itself or is there any speed blocker within
the drivers that slows down the scanners that much?

The scanner may not be able to acquire data as fast as the bus can
transmit the data. Define "painful slow" more exactly--"My scanner
takes N seconds to acquire an image that's X by Y pixels, 8-bit RGB" is
much easier to deal with than a vague "too slow" reference.

You should also examine your machine's USB chipset; "lspci -v | grep
HCI" should show at least one EHCI device. (Sorry, I don't know what
the equivalent command would be in Windows.) Also, not all the USB
ports on your motherboard will be USB 2. Look in your motherboard
manual; it should say which ports are USB 2 and which ports are USB 1.
If your scanner is plugged into a USB 1 port, it'll be slower.

I was told there might be any kind of copyleft agreement in order to
slow down those consumer devices!?

Did someone change the definition of "copyleft" when I wasn't looking?
The word is usually used to refer to things released under the GPL, BSD,
MIT, Artistic, or similar licenses, and is shorthand for "the person who
originally wrote this retains copyright, but anybody can look at the
source and anybody is welcome to use the source in their own projects if
they follow @CONDITIONS."

I'd think that if manufacturers of consumer products had such an
agreement, their USB 2 products would get stomped in the long term as
consumers realized that USB 2 was slower than Firewire.[0] OTOH, ISTR
seeing something about "USB 2 full speed" vs. "USB 2 high speed" about 6
months back, and the article said that one was slower than the other. I
actually don't have any USB 2 peripherals right now, so I don't care
that much, but you might want to go Googling. HTH anyway,

[0] This assumes that companies' marketing and sales departments think
further ahead than the next quarterly report, which may not always be
true.

 

[Martin Trautmann]

Theoretical max data rate for USB 2 is 480 Mbit/second, much higher than
the theoretical max data rate for USB 1,

Agreed, although your numbers do prove the real world, which is much
less.

The scanner may not be able to acquire data as fast as the bus can
transmit the data. Define "painful slow" more exactly--"My scanner
takes N seconds to acquire an image that's X by Y pixels, 8-bit RGB" is
much easier to deal with than a vague "too slow" reference.

A4 scan (that's about 11 x 8 ", 30 x 21 cm)
300 dpi, 256 grey : 40 s (10 s init, 30 s scan, 8.4 MB .tif)
600 dpi, 24 bits color: 380 s (20 s init, 360 s scan, 100 MB .tif)
600 dpi, 48 bits color: 420 s (20 s init, 400 s scan, 200 MB .tif)

That's about 200 MB in 400 seconds or up to 1MB/s - the amount of data
itself might be fast enough for USB 1.1. On the other hand the image
scan does not stream continously.

You should also examine your machine's USB chipset; "lspci -v | grep
HCI" should show at least one EHCI device.

I'll give this a try

Also, not all the USB
ports on your motherboard will be USB 2. Look in your motherboard
manual; it should say which ports are USB 2 and which ports are USB 1.

All external ports are USB 2.

Did someone change the definition of "copyleft" when I wasn't looking?

no official re-definition. It was my personal variation, since the
official copyright would permit scanning documents, while any more or
less inofficial agreement would reduce this right to something more or
LESS useful.

I'd think that if manufacturers of consumer products had such an
agreement, their USB 2 products would get stomped in the long term as
consumers realized that USB 2 was slower than Firewire.[0]

I don't know any FireWire consumer scanners yet. Thus it's diffcult to
say whether the limitation is FW, USB2 or 'consumer'.

That's why I wonder whether there's some kind of crippling scanner speed
or whether the hardware is really that slow.

 

[Jim]

That's about 200 MB in 400 seconds or up to 1MB/s - the amount of data
itself might be fast enough for USB 1.1. On the other hand the image
scan does not stream continously.

One might conclude from this result is that the scanner is the limiting
part.
Jim

 

[James Silverton]

Hi all,

is there actually any use for USB 2.0?

It is certainly much faster and I use it for downloading images from
my camera, connecting to my cable modem and my Canon scanner.

 

[Martin Trautmann]

One might conclude from this result is that the scanner is the limiting
part.

Yes, it's *mainly* the scanner, I guess. But I'd have to prove via
another USB1 interface whether it would be even slower

Example:

380 s scan, 20 s transfer of 200 MB via USB 2 at 10 MB/s, total 400 s

.... or perhaps
380 s scan, 620 s transfer of 200 MB via USB 1.1 at 325 KB/s, total 1000 s

.... or perhaps
10 s scan, limited by USB transfer

.... or might be
10 s real scan time, blown up to 400 s...


Since test results showed that e.g. the Microtek ScanMaker 6000 is the
slowest of its class, I doubt that it actually could do it any faster. I
guess the consumer scanners really are that slow. I feel it's an urban
legend that the companies made them that slow on purpose and without any
need.

But on the other hand - who knows. It's well known by now that many
scanner drivers are crippled not to scan certain bank notes, as well as
printers won't print them.

 

[Martin Trautmann]

It is certainly much faster and I use it for downloading images from
my camera, connecting to my cable modem and my Canon scanner.

I agree that it will be much faster for downloading from your camera -
even if a scanner is connected to the USB.

My question (in Newsgroups: comp.periphs.scanners) is whether there's
actually any use for the combination of USB2 and consumer priced
scanners. I feel that the scanner itself is a limiting factor, while
USB1.1 would be good enough for scanning.

 

[Wayne Fulton]

My question (in Newsgroups: comp.periphs.scanners) is whether there's
actually any use for the combination of USB2 and consumer priced
scanners. I feel that the scanner itself is a limiting factor, while
USB1.1 would be good enough for scanning.

Scanners sample data.

No scanner can go nearly as fast as the Hi-Speed USB 2.0 bus rating (nor
Firewire rating or SCSI rating) but yes, many scanners can go a little
faster than the USB 1.1 rating. Yes, the faster bus is quite nice to
have. We didnt much like USB 1.1 for scanners, too slow.

But you will never see any scanner achieve the faster bus speeds, because
the scanner has to stop and sample each scan line, each of which is a
timed opertation (accumulating photons). The bus must wait on the
sampled data. Devices like disks and cameras dont have to stop and
sample anything, they simply move existing bytes, so you will see those
devices achieving a greater fraction of the theoretical total bus rating.

 

[J. A. Mc.]

I don't know any FireWire consumer scanners yet. Thus it's diffcult to
say whether the limitation is FW, USB2 or 'consumer'.

Why would you not call the Epson 3200 (and similar) scanners "consumer
scanners"? Sold in retail stores to average 'Joes'.

 

[J. A. Mc.]

Hi all,

is there actually any use for USB 2.0?

Hmmm ... Laptop with native USB 2.0 ports (3).
USB mouse, USB 2.0 External 160 GB drive, USB 2.0 Epson 3200 Scanner,
External Hardware Video Encoder using USB 2.0 to laptop, External USB 2.0
16X DVD Burner ... yeah I have real use for it!

 

[Steven]

My question (in Newsgroups: comp.periphs.scanners) is whether there's
actually any use for the combination of USB2 and consumer priced
scanners. I feel that the scanner itself is a limiting factor, while
USB1.1 would be good enough for scanning.

The Canon FS4000US has USB1.1 and SCSI connections. USB1.1 is
definitely a limiting factor as scans can take about twice as long.
With SCSI the scanner can output about 2MB/s.

-- Steven

 

[James Silverton]

Hmmm ... Laptop with native USB 2.0 ports (3).
USB mouse, USB 2.0 External 160 GB drive, USB 2.0 Epson 3200
Scanner,
External Hardware Video Encoder using USB 2.0 to laptop, External
USB
2.0 16X DVD Burner ... yeah I have real use for it!

Oh yes! My backup device is a USB external hard drive!

 

[Martin Trautmann]

But you will never see any scanner achieve the faster bus speeds, because
the scanner has to stop and sample each scan line, each of which is a
timed opertation (accumulating photons). The bus must wait on the
sampled data.

True - but while I've seen a Microteck add, claiming an incredible > 800
Megapixel resolution compared to a digital camera, this digital camera
is able to handle about 10 MP in 1/1000 s (or a full page 800 MP scan in
less that 1/10 s ;-), the scanner needs a certain amount of mechanical
movement, too.

However, the prescan takes < 10 s. This time could be good enough for a
full page scan, too. It's not the CCD design itself that has to be that
slow - professional scanners can do a full page in < 1 s.

But again this falls back to the question whether cheap consumer
scanners are designed to be that slow or whether they actually can't be
faster while being that cheap.

 

[Martin Trautmann]

Why would you not call the Epson 3200 (and similar) scanners "consumer
scanners"? Sold in retail stores to average 'Joes'.

Ah, thanks, I did not note up to now that the Epson Perfection 3200
Photo has Firewire. The common ads name USB2 only. However, the local
price is about 350 EUR... Hm, it was down to 200 EUR some time. I guess
the product is gone, replaced by the 4180 from 210 EUR on - but no more
FireWire.

The MicroTek Scanmaker 6000 costs 66 EUR:
http://www.aldi-sued.de/product_special/product_108.html

 

[Martin Trautmann]

Oh yes! My backup device is a USB external hard drive!

I prefer an external FireWire hard drive, although I got FW400 only.

However, the question 'any use for USB2.0' was aimed at Newsgroups:
comp.periphs.scanners - and not any other peripherals. I'm afraid that I
did not make clear enough:

is there actually any use for USB 2.0 within consumer scanners

 

[James Silverton]

I prefer an external FireWire hard drive, although I got FW400 only.

However, the question 'any use for USB2.0' was aimed at Newsgroups:
comp.periphs.scanners - and not any other peripherals. I'm afraid
that I did not make clear enough:

is there actually any use for USB 2.0 within consumer scanners

If you meant to be that specific, my Canon D1250 is about 2 years and
uses USB 2.0. It's a very satisfactory flatbed and the negative and
slide attachment works quite well even if the scanner has been
superceded.

 

[Martin Trautmann]

If you meant to be that specific, my Canon D1250 is about 2 years and
uses USB 2.0. It's a very satisfactory flatbed and the negative and
slide attachment works quite well even if the scanner has been
superceded.

.... and it is much slower on a USB 1.1 port than on USB2?

 

[James Silverton]

... and it is much slower on a USB 1.1 port than on USB2?

I've never done the experiment and I bought it because it could use
2.0. The manual estimates 4msec/line at 600dpi with the 2.0
connection. With USB 1.1, the value is 16msec/line. The values for
different tasks usually have the same 4 x ratio.

 

[Martin Trautmann]

I've never done the experiment and I bought it because it could use
2.0. The manual estimates 4msec/line at 600dpi with the 2.0
connection. With USB 1.1, the value is 16msec/line. The values for
different tasks usually have the same 4 x ratio.

4 ms/line - this would be 26.4 s for a full page of 11" @ 600 dpi. Is it
really that fast?

A width of 8" at 48 bits/pixel and 600 dpi is 28.1 KB / 4 ms = 7 MB/s.
Not very impressive.

But the factor is interesting: Taking 4 times for USB1.1 seems to be
close to the max. speed of 12 Mb/s.

Thus USB2 could be 40 times faster (= 480 Mb/s / 12 Mb/s), but in
reality is only 4 times faster.

So USB2 is not fast up to the limit, but is significantly faster for
scanning, too.

 

[J. A. Mc.]

I prefer an external FireWire hard drive, although I got FW400 only.

However, the question 'any use for USB2.0' was aimed at Newsgroups:
comp.periphs.scanners - and not any other peripherals. I'm afraid that I
did not make clear enough:

is there actually any use for USB 2.0 within consumer scanners

Did you miss the "USB 2.0 Epson 3200 Scanner" referenced above?