Using a resolver's output signals for measuring the fastening socket's "angle of turn“ introduces an angle measurement error because of the mechanical windup between the socket and the resolver (wind-up does not contribute to turning the socket). The amount of wind-up is proportional to the length of the spindle and the amount of torque delivered to the fastener. The total angle measured during a tightening (from Torque Threshold to final angle) consists of the wind-up plus the socket's rotation angle. The "Wind-up Compensation" feature measures the "wind-up" angle and subtracts it from the total measured angle to report the true angle of turn for the socket.
When the tightening is complete and the amount of torque on the fastener drops to 7/8 of the peak torque obtained during the tightening (spindle starting to relax), the step's algorithm counts the number of degrees the spindle rotates until the torque reaches the programmed Torque Threshold value. This angle measurement is the amount of wind-up and is subtracted from the tightening total angle of turn to get the true socket angle of rotation.