Huangyang Analog control

ENCODER_SCALE = -150.0
MAX_OUTPUT = 2990
OUTPUT_SCALE = 2990
OUTPUT_MIN_LIMIT = 300
OUTPUT_MAX_LIMIT = 2990

Hmm. Are those definitely in the [SPINDLE_9] section?

Yep,

Or I wired something wrong so that the VFD will get 10v once I enable the spindle.

Maybe the VFD isn't set up for analogue speed control?

This has been a very useful thread. With Andy's advice, I've got the spindle Enable/Dir outputs working on my 7i78. Thanks also to timmert for confirming these connections. I also managed to change my vfd to Enable/Dir, instead of Forward/Reverse (P39 1 is the setting on my NF-9000). I can now get rid of the relays, and free up two outputs on the 7i78.
The orient function also works better now. Thanks to all who contributed.

Yep that's the problem
Need to setup the speed control
When I turn the potentiometer on the vfd I can adjust RPM.
This should be not working when it's setup for analog speed control