#378 gscan2pdf claims scanner is "busy" when not connected

[Jan]

When gscan2pdf starts looking for my printer and the printer is switched off, I receive the following error message:

Error opening device: opening device 'smfp:usb;04e8;343d;Z4OQBAFC201175B': Device busy

This is confusing as the printer is only switched off.
I tried version 2.6.7 and it correctly reports:

No devices found

My scanner is a Samsung CLX-3180 connected via USB

[Jeffrey Ratcliffe]

In v2.7.0, I added an option to cache the device list, as for most people, this does not change (a few machines get a different device ID between reboots), this saves several seconds starting gscan2pdf for most people.

Most backends return "invalid argument" if the scanner is off. Yours evidently returns "Device busy". I'll check for this as well in future, and you should see this in the next release.

In the mean time, you can get the behaviour of v2.6.7 by turning off the "Cache device list" option in Edit/Preferences.

[Jeffrey Ratcliffe]

If you would like to test the fix, I've attached the patch.

You can apply it with:

sudo patch -p1 /usr/bin/gscan2pdf < 0002-Recognise-that-the-smfp-backend-returns-Device-busy-.patch

[Jan]

Cool, thanks that is a neat new menu.

As a test I selected "don't show this message again" and tried once more to scan with my scanner turned off. Now I see "gscan2pdf: must open device before starting scan" which makes more sense than "device busy". Great job!