Working on a VMC and my spindle won't change speed using the "S" command. The only way I can get the spindle to change speed is to manually enter a speed into the spindle speed DRO. I have even tried writing a G Code program that varies the spindle speed and it still has no effect. My spindle works great M3, M4, and M5 all work correctly and the spindle is calibrated, the only issue is the S command in MDI or G Code.
Any thoughts?
-Chad