Spindle servo step/dir Problems

Hello People,i have a 3,7kw Servo from szgh that i would like to use as my Spindle Servo via step/dir(external pulse control).
To be more precise i am using a original Mesa 7i95 and the SZGH Servo is SZGH09-2-24-3,7/5,5-4-1500 with a max speed of 15000 rpm.
I can send  the manual for the spindle servo if s1 feels very motivated to read that.

I am a novice with linuxcnc but i watched a video from talla83 and suprisingly got the spindle to turn. I am able to adjust speeds/direction with the according commands.

There is some stuff that does not work.
First vmc_2.halof all using M3 turns the spindle ccw and m4 turns it cw. It should be the other way around. I checked the wiring first and everything seems to be correct as seen in the table for the encoder.
SZGH-ServoMesa 7i950A


0A+ QA3
0A- /QA3
0B+ QB3
0B- /QB3
0Z+ IDX3
0Z- /IDX3

I also checked if the step/dir was correct and it is(polarity too).
If i run the spindle via mdi M3 s200 i get this in halshow (attached picture M3 S200 with positive rps)
If i run the spindle via mdi M4 S200 i get this in halshow (attached picture M4S200 with negative rps)

What i also noticed in Halshow is that whenever i command the rpm to go over 300 the spindle at speed signal does not go true anymore.

I really hope someone can help me here or give me some tipps, i have checked and tried many things but nothing really helped.

Best regards
Nils 

 
 
 
 

Sounds like either the encoder scale or the step/dir scale (or both) are wrong.

Hello PCW,

thank you for the fast answer.

I checked the parameter of the servo with the manufacturer and he told me that the motor resolution per revolution is 1024 which is then *4 4096.
4096/60 = 68.26667 = pulse per second.

How does a wrong scale invert the direction for m3/m4?

i edit the line:
setp hm2_7i95.0.encoder.05.scale - [SPINDLE_0]ENCODER_SCALE

with a minus but that alone does not change the direction of m3/m4.
If i now go ahead and change a direction parameter on my servo drive to reverse
the spindle turns cw via m3 and ccw via m4 while spindle-fb-rps and spindle-speed-rps signal are both positive at least tho still slightly different values.

So i guess i can hack my way around the m3/m4 problem but still the problem with the speed is not solved by this.

at a certain speed close to 1000 rpm and above the spindle-at-speed never becomes true.

You need to reverse the sign of the step scale (or invert the direction output)
to reverse the spindle

 

i get what you mean but i dont have a step scale/ direction output in my hal.

Its this (in the ini file)

OUTPUT_SCALE = 68.26667

i did invert it to:
OUTPUT_SCALE = -68.26667

and now the spindle turns correct.

The Problem with the difference between spindle-fb-rps and spindle-speed-rps still persists tho. spindle-fb-rps is negative and spindle-speed-rps is positive (in case of m3).
This lead to spindle-at-speed never beeing true.

Edit: even when i invert the encoder scale the difference btw. the fb rps and speed rps(commanded) is too big for spindle at speed to be true.