dear hood this card can use a closed loop but i use it as v/f with pg and this make it work like servo to do that i set parameter a1-02 to 1 see pages 4-5,4-7,4-14,5-8 also parameter from f1-0 t0 f1-14 is to adjust pg page 5=36,5-37 and this also like mach 3 parameter
and the most important is puls train i/o parameters fro h6-0 to h6-7 page 5-51
page 6-30 it explain how puls train work 
so that by the end this inverter is controlling after this adjustment according puls train when we set the puls train reference for example 25khz equivalent to motor freq. 5o hz so if the freq. in from mach 3 is changed the speed will change because the freq. will  change the output freq. but the priod will be the same
all the best

I have not read the manual fully and will look at the pages you have pointed out. However that board is a closed loop speed control and not a closed loop position control, there is to my mind a very big difference between these two things. I will reserve judgement until I have read fully read the manual but at the moment I would say you are wasting your time, then again I am usually wrong

Hood

Afraid all I can see from reading the manual is you have precise control over the speed but I fear you have no real control over position, at least to the degree of accuracy that is required for a machine tooll. Your out of position tests which vary with each speed  seem to verify this.
Hood

even if this according to mach3 manual i can do through speed control chapter 4 page 4-12 pwm control as follow
3. PWM motor control
As an alternative to Step and Direction control, Mach3 will output a pulse width modulated
signal whose duty cycle is the percentage of full speed that you require. You could, for
example, convert the duty cycle of the signal to a voltage ( PWM signal on for 0% of time
gives 0 volts 50% gives 5 volts and 100% gives 10 volts) and use this to control an
induction motor with a variable frequency inverter drive. Alternatively the PWM signal
could be used to trigger a triac in a simple DC speed controller.
Figures 4.12 and 4.13
show the pulse width at
approximately 20% of
the cycle and 50% of the
cycle.
In order for the PWM
spindle speed signal to be
turned into direct current
(actually a direct voltage
is generally used as the input to variable speed drives, but you know what we mean) the
pulse signal it must transformed. In essence a circuit is used to find the average of the pulse
width modulated signal.
The circuit can be a
simple capacitor and
resistor or be much more
complex depending (a)
on how linear you want
the relationship between
the width and the final
output voltage and (b) on
the speed of response
you need to the changing pulse width.

Yes that is all relevant BUT for a spindle not for axis control.
Hood

dear all
thanks for your help and I'm sorry for long time to contact you but rely I'm busy to adjust my machine with this type of inverter . it isn't easy but by the the end and after long fitting today i just finish to adjust x axis and I'm rely succeed 100 % INSHAA' ALLAH
as i told u before now it's work as servo but to reach this that's very important point
1- make motor tuning to adjust motor with encoder and inverter and this tuning should be running tuning
2-adjust pg parmeter
3- adjuster ASR parmeter to adjust feedback from encoder
4-use mode v/f with pg feedback
5- adjust v/f curve and parmeter
thanks for all

Glad to hear you got it working, what is the accuracy for positioning?
Hood

actually now it's less than 1 mm  but the acuirte value I'll cheek tomorrow and tell u because today i chick the value with caliber 1 mm only

Ok thanks.

Hood

dear hood
today i check and i found it 0.2 mm but I'm in need some time to adjust back lash and some parameter on inverter i think after this fine tuning the accuracy will be 0.02 mm but let me try and tell you the result