The letter address S is followed by a specified value in revolutions per minute (rev/min).

Example: (specifies 2100 r/min)

One or more digits following the letter address S are used for the value of the rotational speed. If S0 is input, this command deactivates the spindle rotation and leaves it in a neutral position so that the spindle can be rotated manually, depending on the machine tool. This is quite useful, especially for "dialing-in" the workpiece holder to establish Workpiece Zero coordinates. The value of S is specified in revolutions per minute (r/min).