Thanks for the hints!
The problem is that my controller is a SC400 ( card shown in commented text in cdu31a.c )
but the ports suggested are not working
I get a resource busy message from kernel even if I specify explicitly cdy31a_port=0x634
which should be my port! ( as reported in card manuals )
On other computer I got similar problem on modular ppa, but resolved problem with correct
module dependencies! But in this case a `depmod -a` not resolved the problem.