NI-6251: configuring PFI to behave like standard DIO

Hi,

My project requires reading and writing from the 3 digital subdevices found
on the NI-6251. In that respect I modified the available Simulink blocks to
get the possibility of choosing the subdevice that I want to interact with.
This works fine with the first subdevice, P0. However, the other two
subdevices are PFI X/P1.X and PFI X/P2.X and seem to behave natively in a
different way: I can read, but not write, on P1.X, and I dont seem to be
able to do anything with P2.X.
Seeing as these subdevices are not simple DIO, is there a special
configuration (besides comedi_dio_config() ) to make them behave like normal
DIO subdevices? or at least DI?

Thank you,
Matthieu.