7i95T spindle control via Modbus RS485 and SPINX1A

Ok, that calmed me, I've missed that.
Regarding the output pins, I understood that between SP+ and SP- I should have 10volts, I don't seem to measure anything.
Previously, I was using mesa 7i97 and I was getting the 10v analog from it.

Sorry if I ask stupid questions, I am not quite into electronics

SP+ and SP- need to be supplied with 5 to 20 VDC

Typically this comes from the VFD to maintain full
isolation from the logic side and the noisy VFD side

The spinx1a analog output is basically a potentiometer
replacement, so connects to a VFD where the potentiometer 
connects.
 

I was able to start the spindle, direction works fine, but I have a problem with the speed.
My lathe max speed is 3000 rpm, when I set this speed, the pwm value is 0.999 so almost 1, which I think is correct.
When I set 700rpm, I get 0.23 on the pwm.value, which is also correct, however, the voltage measured between SP- and SPV is 5.8V so it spins way faster than it should.
How can I scale the value of the potentiometer so that between SP- and SPV I get the correct voltage.
Between SP- and SP+ I have 10.75V so this would mean 3000 rpm, so for 1500rpm, between SP- and SPV, I should have 5.37volts or smth like this.

Normally, you would set the PWM scale to the spindle RPM
at SPV+ (so if the spindle RPM is 3000 at 10V, you would set
the PWM scale to 3225 (3000*10.75/10)

Then the PWM value is set directly in RPM.

If you have issues with non-linearity, check
that SPV+ is constant at different spindle settings.
Other possible causes of non-linearity are PID settings
or incorrect PWM frequency

pwm frequency is set to 5000
I've set the scale to 3225, it doesn't seem to make any difference.
I was not using PID for spindle speed, I was using lincurve.
However, I think that as long as PWM value is correct, the problem is somehwere else. I think the PWM value should go between 0 and 1, at max speed its 0.999, at 1500 rpm is almost 0.5, which seems correct to me.

I don't know what else to check

Is this with a SPINX1A?

The SPINX1A should have better than 1% linearity

Does the 10,75V vary?