[sane-devel] How to debug xerox_mfp

[JPT]

Hi,

I got a SCX4726 network printer.
While printing works mostly fine (except some paper size issues)
scanning capability varies a lot over time.

There has been a time when skanlite scanned batches of paper through the
ADF without any problems.
But currently it just doesn't work. This problem hunts me for years now.

I added the line
	tcp SCX4726.fritz.box
to /etc/sane.d/xerox_mfp.conf
which wasn't neccessary earlier. Now sane finds the printer, well the
scanner.

When I scan something, the first page works but on the second page
something crashes which needs powercycling the printer.

I do not have a personal firewall.

On Kubuntu 23.10 via LAN cable:
	scanimage (sane-backends) 1.2.1-debian; backend version 1.2.1

Just now not even scanimage -L works.

from fresh  installation of Manjaro Stable via wifi is rather slow.

	scanimage (sane-backends) 1.2.1; backend version 1.2.1
	$ scanimage -L
	device `xerox_mfp:tcp SCX4726.fritz.box' is a Samsung SCX-472x Series
multi-function peripheral


$scanimage --resolution 200 --mode Gray --source ADF --jpeg=no --batch
--progress --verbose --format=png
Scanning infinity pages, incrementing by 1, numbering from 1
Scanning page 1
scanimage: scanning image of size 1728x2767 pixels at 8 bits/pixel
scanimage: acquiring gray frame
scanimage: min/max graylevel value = 0/255
scanimage: read 4781376 bytes in total
Scanned page 1. (scanner status = 5)
Scanning page 2
scanimage: sane_start: Error during device I/O
Batch terminated, 1 page scanned

after that, the printer draws the complete batch of paper and something
crashes which requires power cycling the printer.

The printer starts scanning the next page at about 80% data received. is
this too early?

scanning from Win10 Virtualbox using Samsung software usually works. but
requires virtualbox kernel modules. which currently don't work 8)


is there any background service i could restart?

how do I enable debug logging?
I tried
	SANE_DEBUG_XEROX_MFP=30
but nothing changed. where should it log to?


thank you very much

JPT