[sane-devel] scanadf on Mac OS X

[m. allan noah]

On 10/12/07, Yoshi <ml at otani-shokai.com> wrote:
> Hello Allan:
> Thank you for your reply very much.
> This mail is not posted to ML because the log files are little large.
>
> The results seem not to be over a same rule, and my analyzing is
> still going. But now it seems that scanimage -L doesn't do something
> harm
> on detecting scanner, but any other actions 'scanimage --help' or
> 'scanimage'
> do something on loosing scanner.
>
> Unplug/replug the scanner was a clue. After repluging, scanimage -L
> detects the scanner. But after 'scanimage --help', 'scanimage -L'
> begins to
> fail to detect scanner, although when 'scanimage --help', the scanner
> was listed
> on the bottom of the help display.
>
> Then replug the scanner and do 'scanimage --help -d DEVICE' several
> times, the scanner was detected on the device list each time. But after
> then doing 'scanimage -L' couldn't detect scanner.
>
> Then replug the scanner and do 'scanimage > hoge.pnm' to get image,
> but the log says error 'Error during device I/O'. After that
> 'scanimage -L'
> could no longer detect the scanner.
>
> The attaching log is following and I would like you to take a look
> and check them:
> sane_debug21.txt and res21: scanimage -L succeeded log and its result
> sane_debug23.txt and res23: scanimage -L failed after scanimage --help
> Replug...
> sane_debug41.txt: scanimage > hoge.pnm failed
>
> Thank you very much.
>
> Yoshi
>

interesting.

`scanimage -L` only asks the installed backends to list any scanners
they have found. the fujitsu backend closes the device after initial
detection. this allows another backend to open the scanner.

if you use `scanimage > file`  or `scanimage --help`, the same
detection step is done, then the first scanner in the system is
reopened, and commands are sent. we fail on the very first command.

if you run `scanimage -d devicename --help`, i believe the detection
code is not run, so we only open the scanner once, and the command
proceeds normally.

so- it appears that after we close the usb device, we cannot re-open
it under osx? we need some OSX/USB help here.

allan
-- 
"The truth is an offense, but not a sin"