Power or Float-Exception
SANE-controlled Scanner via USB-Hub
As always nothing changed but nevertheless a common work process doesn't work anymore. Additionally it is a very simple task done in a few minutes. Pressure rises and no matter where you search for the solution it is always found where you look last.
My intention was to scan a piece of paper an edit a bit in Gimp. The scanner started to make some noise but very soon SANE crashed with a floating point exception. So I started to search 15min through various search results. Articles were often quite old and none fit my problem.
That is why I started search at the opposite end and checked the hardware. By simply re-plugging SANE did what it should. And like so many times before it was power consumption on the USB-hub. Indeed I changed my working process. Instead of changing many USB plugs between desktop and laptop I added a USB-hub. But it didn't provide enough power to the devices. That's why starting to scan drew too much power and data transfer was impossible. SANE crashed accordingly with a misleading error message so I assumed first it was a software problem.
I wouldn't expect SANE notifying about the lack of electric power. But the floating point exception is also too general. There was also not enough space left in the USB specification to signal a sudden voltage drop. And if there were it'd rather be a luxury function not to be expected in a 15€ product.