Eddy, there is some confusion from Kendrick here - I have spoken to K on the telephone and he has a 400hz vfd and a 24k spindle. I do not think that he can control the spindle speed with his software (only from the vfd and he is quite happy with that), he is unable to stop/start the spindle and I think he should be able to do that if someone can advise him. I can't help because I use dedicated controllers on both of my machines (commercial system, not mac), but I am sure someone on here can point him in the right direction. G.