A machine having a rotor including permanent magnets and field coils. The system includes a positive-displacement pump made up of a stator and of a rotor, the stator being inserted in the drill rods, and the rotor being assembled to operating rods arranged within the drill rods. The commissure tips are elongated relative to more simple shapes. A method enables the use of a minimum number of link modules by cycling data between a set of master link modules and a substantially smaller set of slave link modules.