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Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #70 on: June 07, 2019, 07:37:47 AM »
Hi,

Quote
If P1-46 defaults to 2500, then this guide would be incorrect if P1-46 actually set the encoder count that the drive uses.

That is exactly the same train of thought that I went down......but as you see P1-46 does default to 2500 for an effective
10000 count encoder. Have a look at the manual that OP posted, my reading of leads me to conclude the P1-46 sets the
effective count of the encoder, not just the digital outputs, but the primary encoder loop. Pretty kool!!

Craig
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Offline ger21

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Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #71 on: June 07, 2019, 07:45:35 AM »
I don't think so, but testing will be required to prove otherwise.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #72 on: June 09, 2019, 03:00:39 AM »
Hi,
page 203 Chapter7

Craig
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Offline Hood

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Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #73 on: June 09, 2019, 04:19:47 AM »
Is that not saying how to set up for the output signal of the encoder, ie for feedback use?
Just had a quick squint at the manual and it seems to say
1.the encoder is 160,000ppr.
2.you can set the electronic gearing so as to allow your step inputs to be suitable for your controller.
3. you can set the encoder output so that feedback is of a suitable range for your control, if it requires feedback, think CSMIO/IP-A

I may be totally wrong as I have only had a quick look but that is what it seems to be saying to me.
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #74 on: June 09, 2019, 04:41:33 AM »
Hi,

Quote
1.the encoder is 160,000ppr.
2.you can set the electronic gearing so as to allow your step inputs to be suitable for your controller.

That was my initial impression also....but the more I read I came to the opposite conclusion, namely that you can
program the encoder to have anywhere between 4 and 40,000 lines. It is the synthesized encoder that is used as the
primary feedback and electronic gearing is applied to that....not the 160,000ppr.

Craig
My wife left with my best friend...
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Offline Hood

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Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #75 on: June 09, 2019, 05:17:23 AM »
I suppose the only way we will know for sure is for Gerry or someone else who has one, to do some experimenting and post the results.
The Chinese do things in a strange way to our eyes but they are equally valid and may have benefits, the setting of steps per unit in the SZGH control I have on the lathe being one, it took me quite a while to get my head around what they were meaning but once I had things hooked up it became clear as I could see the results :)
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #76 on: September 10, 2019, 01:26:58 AM »
Hi All,
I have taken delivery in the last couple of days of a brand new Delta 400W B2 series servo and drive.

I can confirm that the native and raw encoder count is 160,000 count (40,000 lines) per rev and that the electronic
gear ratio applies to that 160,000 number.

The manual shows something which would suggest this is not so, see attached.
On the other hand the software tuning page suggests exactly as Gerry and Hood have contended.
Experimentation has proved conclusively that the gear ratio applies to the raw 160,000 count encoder.

Delta is a Taiwanese brand and the manual is in 'Chinglish' but is pretty good....as "Chinglish' goes.

Like any modern servo its going to take a great deal of experimenting to explore all the tuning features.

I was of the opinion that I would have to use a 3:1 or 5:1 gearbox to match my existing steppers but the stall
torque on these small servos has to be experienced to be believed. I'm going to try direct coupling them instead,
they certainly feel like they have the grunt to match my steppers WITHOUT a reduction box.

Craig
My wife left with my best friend...
     and I miss him!
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #77 on: October 16, 2019, 02:30:50 AM »
Hi,
I've started a new mill project, much bigger and more powerful than my mini-mill. I have some great 32mm diameter, 5mm
pitch, C5 double-nut ground ballscrews for the X,Y and Z axes.

I decided to get three new 750W Delta servos, B2 series. I got two plain servos/drives and one braked servo/drive for the Z
axis. I took delivery of them a few days ago but ran into a hitch....operator error.

In particular as I posted earlier the electronic gearing applies to to the 160,000 count encoder. What I wanted to do was
have 16000 as numerator and 100 as denominator. These numbers were for me to experiment with the servos using a signal
generator as the pulse source.

f2=f1 x16000 / 100

Thus if I feed the servo a 1kHz signal from my signal generator it would, after the electronic gearing generate an f2
of 1600kHz and thus spin the rotor at 10 revs per second or 600rpm......simple right!

I programmed P1-44 and P1-45 accordingly....or so I thought. I was using the buttons on the drive to set the parameters.
The range of numbers that can legally be used as numerator/denominator are very large, up to 10 decimal digits. The display
on the front of the drive is only five digits wide. Thus you can only see part of the particular parameter without hitting
<shift> to observe the higher order digits. What I had done , accidentally was erroneously programmed 116000 instead
of 16000 as numerator. It was not apparent that I had made a mistake because the higher order digit was obscured from
my view.

This lead to several hours frustration before I tumbled to my mistake.

What helped in the end was that I had, as a separate purchase bought a USB-to-IEEE1390 cable that I could program
the Delta drives with the manufacturer software. When I finally got the software installed and got the right drivers installed on
my PC and was able to read the programmed state of the servo the mistake I had made with the numerator became obvious.

Indeed programming the drive is just so much easier with the software than trying to push little teeny-tiny buttons
that I would have to recommend that you consider a programming cable an essential item if you buy a Delta servo.

The USB-to-IEEE1390 that I bought was manufactured by Delta and cost me $62 including shipping.
RS232-to-IEEE1390 can be had for less, about $30. Of course you only need one cable, you can program multiple
drives in succession, no need for a cable for each.

Aside from the great assistance the software gives you to program the drive there is a comprehensive scope and monitoring
suite that allows very detailed tuning analysis. All in all the manufacturer software and a cable to hook your PC to the
drive is all but essential in my opinion.

Craig
My wife left with my best friend...
     and I miss him!
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #78 on: October 29, 2019, 06:08:12 AM »
Hi,
I've started a new mill project, much bigger and more powerful than my mini-mill. I have some great 32mm diameter, 5mm
pitch, C5 double-nut ground ballscrews for the X,Y and Z axes.

I decided to get three new 750W Delta servos, B2 series. I got two plain servos/drives and one braked servo/drive for the Z
axis. I took delivery of them a few days ago but ran into a hitch....operator error.


What is the accuracy your are aiming at ? Even with 1micro meter (1um)  I assume you are unable to hit limit of those delta encoders (cpr 160,000 ?) as your maximum pulse rate is 4Mhz ?

my math:
32mm ball screw diameter / 1um of CNC machine accuracy = 32,000 ppr,
encoder resolution = 32,000 * 4 = 128,000 cpr (below delta encoder spec)

Finally 128,000 cpr * (1800 rpm / 60) = 3 840 000 (imp / sec) so almost 4Mhz of pulse rate with 1800 rpm max

What is your view?
« Last Edit: October 29, 2019, 06:10:25 AM by Hortensie »
Re: Servio motor Delta adas b2 Software and electronic gear ratio
« Reply #79 on: October 29, 2019, 08:57:13 AM »
Hi,

Quote
my math:
32mm ball screw diameter / 1um of CNC machine accuracy = 32,000 ppr,
encoder resolution = 32,000 * 4 = 128,000 cpr (below delta encoder spec)

No, not quite.....the diameter of the screw is 32mm, the pitch is 5mm per rev. Thus for a resolution of 1um
I require an effective pulse rate of 5000 cpr, the numerator/denominator could be:

160,000=5000 x N/D
so N/D =32

Thus the choice of N and D is very wide, for instance if D=1 then N=32 OR
D=10 then N=320 OR
D=25 then N=800 and so on.

At 3000 rpm (50 rev per sec) the pulse rate is:
pulse rate=50 x 5000
              =250kHz.

As you point out the ESS has a max rate of 4Mhz, so at 250kHz its cruising. 250kHz is a little faster than the max recommended
single ended (open collector) signaling rate but very comfortably within the 'low speed' differential signaling spec of the servo
drive of 500kHz.

I have some experience with an Allen Bradley servo which I wanted to signal at 466.66kHz. Its servo drive has a recommended
max differential signal rate of 500kHz and a single ended rate of 200kHz. I can assure you that while 466.66kHz is possible
its much easier to signal at a lower rate. Thus I reduced the angular resolution to 2000 cpr (from the encoder max of 8000cpr)
and got the signaling rate down to 116.66kHz which can be done comfortably with a single ended transistor.
Note that this servo is used as a direct drive spindle which gives a resolution of 10.8 arc min ( with 2000 cpr) from a max
resolution of 2.7 arc min (with 8000 cpr). I practice even 10.8 arc min is much greater than I require. Reducing the resolution
has made the whole thing easier to do and still exceed my actual requirements.

My existing mini-mill has a linear resolution of 1um and is very adequate. Thus I am quite happy to aim for 1um resolution
in this new build. I could, given the capacity of the servo encoder, have a resolution of 0.03125um ( 31nm!!!) but at the
expense of complexity of the signaling side of the design. I struggle to even measure 1um......let alone 30nm so why
bother?

The rated speed of the 750W B2 series servos is 3000 rpm. Direct coupled to a 5mm pitch ballscrew results in a max axis
speed of 15m/min which is a marked increase from my existing mill of 1.2m/min. I have experimented with pushing the
max speed parameter out to 5000rpm, the servos max speed (cf rated of 3000rpm) and they still work a treat.
Thus I could have rapids (G0's) of 25m/min in field weakened mode  and full rated thrust for machining moves (G1's) of
15m/min while still maintaining 1um resolution and a max signaling rate of 416.66kHz, well within the 'low speed'
differential spec of the drives. As far as I'm concerned that is speed AND resolution beyond what I ever anticipated
I could achieve with a hobby machine. If I want to use the full acceleration potential of my existing mini-mill (I can
tune it to 1g accel easily enough) I have to tie the machine to the wall or the machine tries to dance all over the floor.
The practical limit for the machine is about 0.05 g without undue machine motion and still provides excellent tool path
following (at modest axis speeds).

These 750W servos offer at least a 50 fold improvement in potential over the existing stepper/reduction drives I currently
use. Thus with the X axis bed/ballscrew/rails/vice/workpiece weighing over 200kg if I tune the axis to 1g acceleration
(of which the servos are more than capable of) then I'm going to have to bolt this machine to a concrete floor just to stop
it lurching around threatening to crush any-one or any-thing in its path!

The speed, torque and resolution of these servos continues to exceed my expectations. 15 m/min G1's sounds fine on paper
but when you see the axis machining at 15m/min you realize just how much power and even how much potential damage
can be done.....its scary!! Fun scary.....but still scary.

Craig
My wife left with my best friend...
     and I miss him!