[sane-devel] USB to parallel port converters

[Neil Youngman]

On Saturday 08 December 2007 14:50, Julian Stacey wrote:
> Reference:
> > From:		Neil Youngman <ny at youngman.org.uk>
> > Date:		Sat, 8 Dec 2007 14:20:20 +0000
> > Message-id:	<200712081420.20137.ny at youngman.org.uk>
>
> Neil Youngman wrote:
> > On Tuesday 27 November 2007 13:05, Neil Youngman wrote:
> > > I have a Mustek 1200CP parallel scanner, which appears to be supported
> > > by SANE, but no parallel port on my system. I do have a USB to parallel
> > > port converter, which works fine with my printer, but I can't get it to
> > > recognise my scanner.
> > >
> > > sane-find-scanner -p -vv /dev/usb/lp0 doesn't find any scanners. Is
> > > there something else I should try, or won't it work with a converter?
> >
> > No answer to this so far. Should I just give up?
>
> I'm no scanner/sane specialist, but do remember a printer will even
> work with a unidirectional parallel port, data just going computer
> to printer, whereas a scanner feeds a lot of data back, (PC BIOSes
> have various EPP/ECP etc modes, some modes support nibble mode too,
> ie 4 bits each way for a PL-IP connection etc),  So maybe your USB
> to parallel device may need to support bidirectional (if it can), &
> may need to be told to configure itself in bidirectional mode etc.
> How you might set about doing that I cound't advise, but
> would depend on your device manufacturer & which Unix you are using,
> & whatever it's USB control vagaries might be.  Good Luck !

It's an unbranded adapter from ebay, so all I know is what dmesg tells me.

drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 2 if 0 alt 0 
proto 2 vid 0x4348 pid 0x5584
usbcore: registered new driver usblp
drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver

and what I get from cat /proc/bus/usb/devices

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=0000 ProdID=0000 Rev= 2.06
S:  Manufacturer=Linux 2.6.18-5-amd64 uhci_hcd
S:  Product=UHCI Host Controller
S:  SerialNumber=0000:00:1d.1
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   2 Ivl=255ms

That doesn't tell me much. I suspect it's more about the hub than the adapter?

I would be surprised if the adapter didn't support bidirectional ECP/EPP 
modes, but I could always be wrong. It was advertised as a printer adapter. 
There may be some modes required for scanners that it doesn't support, 
however I suspect that the problem is more likely to be SANE assuming that 
parallel port devices are only found on parallel ports and not on USB. Does 
anyone know if this is the case?

Neil