VFD and PWM Signal setup

I just complete wiring up a 110v, 800w spindle motor and VFD and setup the VFD program parameters. Spindle and VFD seems to be working correctly in manual mode.

The next is to setup is the PWM signal to set PG0070 to1 to AutoStart the motor. So, far have changed the $30 to 24000 from 1000 and determined that the IOT relay (originally set up to start router and dust collection) will activate at 5000 RPM (M3 S5000) reliability.

I’m thinking at I can wire the IOT relay and the spindle in series and have a system that start my vacuum and motor as long as I have the min RPM above S5000 in the G-code.

        Is wiring of the IOT and spindle in series a bad Idea?  

        What RPM range do most people use?  My range would be S5000
        to S24000 RPM if I use the IOT relay in series with the spindle.

        Is there a better way to control the dust collector?

Thanks for your option on the above questions, John