Shows the device (CanoScan FP320P) has some newly added basic support in sane-backends-1.0.22.
and F15 (presumably F16) have this latest set of backends.
If you've installled the package then a
man 5 sane-canon_pp
describes the FP320p interface and configuration.
So you need F15 or F16 (or else this newer sane backends).
You need the sane-backend package.
You need to manually edit the /etc/sane.d/canon_pp.conf file according the the man page above.
I *think* it says that the 620P settings also apply to the 320P.
So the canon_pp.conf file should (I think) contain
init_mode FB620P parport0
These lines are in the config file but commented out - so uncomment them.