Using QNH (and avoiding confusing terminology for CDFA 2D approaches!):
On the new Airbus kit, you set the DH into the RA field for CAT II/III.
On the new Airbus kit, you set the DA into the BARO field for CAT I.
On the new Airbus kit, you set the MDA into the BARO field for non-precision approaches such as VOR-DME or NDB.
Read further only if perfectly clear.
On the older Airbus models, the RA field is called DH and that is where you set DH for CAT II/III.
On the older Airbus models, the BARO field is called MDA and that is where you set DA for CAT I.
On the older Airbus models, the BARO field is called MDA and that is where you set MDA for non-precision approaches.
Why did Airbus originally decided to call the BARO field MDA? Good question. Maybe DA/MDA was too long, or (M)DA confusing. Nevertheless that is where you put DA for CAT I ILS. There is no DA prompt at all on Airbus, old and new.