So, is there no way?

Is this just a limitation of the SS driver or does the mach3 closed loop controller not work right now?

My expectation as to how it should work is that when I select type in S3000 and my rpm sensor reads say 3060 or something it'll adjust PWM output to 3000/3060*(previous PWM) applying the PID coefficient to smooth out any oscillation that this math will cause.

I am having a simular problem, before I added a smoothe stepper and c32 breakout board I had nearly perfect spindle rpm control thru all ranges. Now i can not get the spindle to work at all in PWM. I have been using anolog voltage off of the c32 BOB and it is far from good.
Can you give me a rough of your configuration to get PWM to work with the SS so maybe I can figure out what I am missing. Thanks, Cork

Hey Cork, sorry for the super long delay, I took a long break from my cnc machine and just recently got back into it and actually started cutting stuff.

Not sure if you still need settings, but mine work with a G540 geckodrive, which outputs 0-10V.

I don't remember exactly why I chose certain settings but I do remember that the G540 had certain pwm requirements as well as the SS.

in the SS config dialog I have my spindle set to 64khz, spindle set to PWM at a 2000Hz rate.
in the Ports & Pins spindle screen I have my use spindle motor output and pwm control checked, base freq is at 50 and min pwm is 0.

From here I think all I had to do is tune the pulley settings until the pwm curve output by mach matched what my spindle did. Therein lies the problem, I'm not using a VFD so the rpm mapping is near impossible as a DC motor doesn't have linear rpm to voltage curves. So I've been trying to get closed loop spindle control but so far has been unable to get it to work. I've yet to try the latest beta SS drivers available though.

Not sure if we can get any more insight from the SS developers as to what's missing here of it it's even possible with the current SS drivers.