The DatumPlane object has no direct constructor; it is created when a Feature object is created. For example, the DatumPlaneByPrincipalPlane method creates a Feature object that creates a DatumPlane object.
The DatumPlane object is derived from the Datum object.
import part mdb.models[name].parts[name].datums[i] import assembly mdb.models[name].rootAssembly.allinstances.datums[i] mdb.models[name].rootAssembly.datums[i] mdb.models[name].rootAssembly.instances[name].datums[i]