# Biesse Rover 322 MESA retrofit

03 Oct 2020 22:10 #184743
The servo period in the ini file has to be 1 or max 2 million, not 6M.
The output scale is wrong for all axis, it should be 10 for the min and max you are using.
Refer to this topic for tuning, wiring and checking everything:

03 Oct 2020 22:15 - 03 Oct 2020 22:18 #184744 by PCW
Replied by PCW on topic Biesse Rover 322 MESA retrofit
I would tend to disagree on the output scale. ideally it should be the machine
velocity (in machine units per second) at 10V, so 10 makes senses if the maximum
speed is 10 mm/second (at a full scale 10V output)

The reason to use this scaling is:
1. FF1 == 1.000
2. PID values are the same for inch and metric machines
3. All the PID values are in normal engineering units
for example, a P value of 1 means: correct the velocity
by 1mm/s for a 1 mm position error
Last edit: 03 Oct 2020 22:18 by PCW.

03 Oct 2020 22:22 #184747
In that case, would the min and max output have to be scaled accordingly or remain at -10 and 10 ?

03 Oct 2020 22:29 #184749 by tom_no
Thanks for input Peter! I'll update the limits tomorrow and test again.

The drives are Yaskawa Servopacks and may well be velocity mode drives. How do I tell for sure?

Can I calculate the correct OUTPUT_SCALE from maximum speed at 10V? IE 75 m/min = 1250 mm/sec?

Also; Having you here; RS-485 control of the VFD should be possible through the 7i77 and it's sserial port, right?

03 Oct 2020 22:31 #184750 by PCW
Replied by PCW on topic Biesse Rover 322 MESA retrofit
They have to be scaled:

OUTPUT_SCALE = 150
OUTPUT_MIN_LIMIT = -150
OUTPUT_MAX_LIMIT = 150

if I set the limits to +- 10, The 7I77 output voltages would be limited to
10/150 or +- 0.6666V
The following user(s) said Thank You: tommylight

03 Oct 2020 22:35 #184752 by tom_no
So in theory I should set OUTPUT_SCALE to 1250 and FF1 to 1.000?
(given that my machine is spec'd at 74 m/min)

03 Oct 2020 22:46 #184753 by tom_no
The servo period reflects the crappy laptop I'm using for testing. Had to crank up the servo period and watchdog timeout to keep the link going. Will replace with a proper computer. Is the servoperiod biting me here?

I've been trying to follow your guide, but struggle as I don't get the error messages needed for the tuning. Also; I believe the acceleration for all axis needs to be considered before starting tuning, not just the jog speed. I mistakenly put in a way high number (copied from the original XNC config) and think I got lucky not stripping teeth of the servo gears. Quite violent.

03 Oct 2020 22:52 #184756 by PCW
Replied by PCW on topic Biesse Rover 322 MESA retrofit

So in theory I should set OUTPUT_SCALE to 1250 and FF1 to 1.000?
(given that my machine is spec'd at 74 m/min)

Output scale would normally be about 10% higher than the maximum design speed
This is to allow "headroom" so the PID can still command a higher speed even at the
machines maximum design speed.

Another way to say this is that at 10V, the machine should be moving about 10%
faster than its design speed

03 Oct 2020 22:59 #184759 by tom_no
Makes sense, can't regulate when already at 100%.
That puts me at a outputscale of 1375 then.

04 Oct 2020 10:55 #184798 by tom_no
Updated my configuration today and the machine immediately ran smoothly. Brings a tear to my eye.

Thanks Peter!

OUTPUT_SCALE = 1375
OUTPUT_MIN_LIMIT = -1375
OUTPUT_MAX_LIMIT = 1375
FF1 = 1.000

Video, in case it did not happen?

The following user(s) said Thank You: tommylight, ehb