Clockwise rotation
Principle diagram.

The stator windings are supplied with 24 V DC at A and B.
Each winding has three conductors, i.e. six in total, of which four are earth leads.
The control unit constantly controls the earthing of the motor's stator windings.
This creates a rotating magnetic field that gradually drives the rotor around in steps.
The control unit stores the setting of the stepping motor when the starter key is turned to 0.