Looking at the flyer for the cpu card it looks like you are using the watchdog output to enable the drives which appears to be correct for this cpu card. I think that the green led should be on when the drives are on because the watchdog signal will be ok. I think that the watchdog output signal is staying on even though you are turning the drives off but I don't know if this is correct for this cpu. I have had a quick look at the servo amp manual but im not sure if it the correct one for your motor. It says that the amp enable should be 12 or 24vdc switched from its own internal supply. Are you using the watchdog signal to switch a relay for the servo amp enable signal?