Hi. I am using a CNC Turning Lathe with FANUC controls. The spindle rpm is always on a constant offset of 20 rpm increase from whatever the value is programmed for spindle speed. I have checked at multiple rpm values but the difference value remains constant. Also the program uses the actual RPM after applying offset for further calculations ( e.g. if I program the RPM to be 50, the actual value of the spindle and what's shown on the output display will be 70. I've verified with tach. Moreover if the feed is in rev/mm and I take output on display in mm/min, it will have calculated in accordance with 70 rpm instead of programmed 50) What could be the cause of this issue.. is it a parameter issue or a mechanical fault related to encoder or motor drive?