After plugging in the usb cable the Fujitsu scanner is found once:

uname -a
scanimage --list-devices

Linux raspberrypi 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l GNU/Linux
device `fujitsu:ScanSnap iX500:10443' is a FUJITSU ScanSnap iX500 scanner

Doing it again, no scanner is found anymore:

scanimage --list-devices

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).

This command finds the Fujtsu (and another unknown scanner) always:

sane-find-scanner -q

found USB scanner (vendor=0x04c5 [Fujitsu], product=0x132b [ScanSnap iX500]) at libusb:001:010
found USB scanner (vendor=0x0424, product=0x7800) at libusb:001:004

Try to use sudo with scanimage (In case it's a permission issue). Try to unplug/plug the scanner for the udev rules to recognize the scanner (In case the usb bus is autosuspended by a power-saving tool like tlp). You might need to configure a dev rule manually for it to work properly. Not all scanners would be supported out of the box.

Check this and this to verify it's a common practice to do such things with some scanners.

Quoting man scanimage

The -L or --list-devices option requests a (partial) list of devices that are available. The list is not complete since some devices may be available, but are not listed in any of the configuration files (which are typically stored in directory /etc/sane.d).

Which explains why if you don't have the correct backend configured in /etc/sane.d, the -L option won't work. sane-find-scanner only checks the device files but not the drivers in /etc/sane.d. sane-find-scanner is your first check whereas scanimage -L is your second.

| improve this answer | |

I had scanbd enabled which in turn intercepted scanimage. sudo systemctl stop scanbd solved it.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.