Quote Originally Posted by GEOFFREY View Post
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.
Starting/stopping the spindle is often done using a output which controls a 5V Relay who's contacts connect to the VFD run Signal.
Often the BOB will have Dedicated on board relay connected to output.

Reason for the Relay is that the VFD run signal will probably be 24V so can't be directly controlled using the 5v Output.