Abstract: A stepping motor turns 45.degree. for each step in response to a digital control signal different than the signals for other step adjacent thereto. An angle sensor produces a digital position indicating signal for sectors centered about the step positions and of the same magnitude as the angle between motor steps. The position indicating signal for a sector corresponds to the digital signal of the motor step that falls within that sector. An evaluation circuit comprising a microprocessor produces an error signal when, after a predetermined elapsed time after receipt of a control signal, a corresponding position indicating signal is not received. The evaluation circuit also checks for correspondence of signal within a minimum time after receipt of a control signal, and failing to find such correspondence assumes that the motor has not performed the directed step.