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After running some prolonged milling sessions with my mill I've decided to go a different route here.

I'm going completely replace the VFD, the gigantic 2kw AC spindle motor and the noisy 6 speed transmission.

I'll be replacing the whole setup with a Delta B3 2kw 400v AC servo rated for max 6000 RPM and use a belt drive with 1:1 ratio pulleys to drive the spindle directly.

This should give me plenty of low end torque, a built in encoder and double the max RPM of what I had before at much lower noise level.

But I just realized that the question of how to read the spindle load from the servo drive still remains. The load is available from the Delta servo drive either as an analog signal or via Modbus.

As I'm using a Mesa 7i96S + 7i84 combo I have no analog inputs available and the Modbus capable RS422/485 port is already used for the 7i84.

What's the best way around this?

Do I try to source a Mesa 7i76EU which has a few analog inputs and replace the Mesa 7i96S board?

Can I use the FPGA expansion port in some clever way without adding too many expansion cards?

 

TheRoslyak wrote:

Well, it turned out that even the most advanced MoveIT can't handle circular interpolation on its own. Need to write the math yourself. Tomorrow, I will try to write the math myself + Ruckig, with the only difference being that I will use complex numbers.
P.S. There was a scientist named Steinmetz who studied alternating current and used complex numbers instead of trigonometry in his manuscripts, which earned him the title of academician.
 

When I was trying out ruckig the problem that I came across was when you give it a set of constraints and a start and end position, it would create the trajectory and satisfy the constraints, but it would overshoot the end point and then move backwards to it. I'm not sure if I was just overlooking something and there are ways to have more control. It seems like its made to get from point A to point B as fast as possible with no restriction that it has to stay on a line segment connecting A and B. There is a paid version with waypoints, but I don't think that really solves the problem. It sounds like you want to generate an exact path and then move along that path while satisfying jerk, acceleration, and velocity constraints.

I might be off, but GLcanon is part of LinuxCNC, the python part that probably deals with OpenGL, and it is mentioned several times on your code above, and i am sure there is a file named glcanon.py included with LinuxCNC, so maybe having a look there sheds some light ... or turns out to be a deep rabbit hole !

Cheers JT I thought I’d been banned and had my IP blocked.

canon is used to call Python functions from C++

That did the trick, I am up and running. Not sure I would've ever figured that out.

PCW wrote:

Since Preempt-RT and RTAI are about equally bad,
I would more expect an issue with the BIOs, power
management etc.

 

I agree, but the fact there are still RT settings active, granted another chance.

An older version of the official ISO had such issues, so if still suing that it would be very good to upgrade to 2.9.2 ISO.
That does imply formatting the drive so do make a backup of the config on a USB.
In the meantime:
forum.linuxcnc.org/38-general-linuxcnc-q...little-issues#226480

I talked to Peter at Mesa today about a problem I am having Linux Debian CNC.
He thought there may be a bug in the version I am running. 
He thinks it is making too many icons in the background so I can't open up any of my apps.
On the top panel is full of connection icons. I always thought that was strange, but everything worked fine until lately.
Now none of the icon work.
Has anyone heard of this?
Thanks
DB    

Right now I'm using these two methods for homing. I have a custom homing process, compiled with homecomp and activates the internal homing of the drives. When the homing is done, I turn off (comment out) from the hal and ini and using just HOME_ABSOLUTE_ENCODER = 2, so no movement on axis.
But still have to solve the jogging problem, becouse before axes are homed, sill allowed to jog the machine out of softlimits. Unfortunately the soflimist are not working while unhomed.

This method is not so comfortable, but working. I'm still looking for better homing solution.

Since Preempt-RT and RTAI are about equally bad,
I would more expect an issue with the BIOs, power
management etc.
 

Well, it turned out that even the most advanced MoveIT can't handle circular interpolation on its own. Need to write the math yourself. Tomorrow, I will try to write the math myself + Ruckig, with the only difference being that I will use complex numbers.
P.S. There was a scientist named Steinmetz who studied alternating current and used complex numbers instead of trigonometry in his manuscripts, which earned him the title of academician.

Thanks a lot, encoder works. Encoder had wrong configuration because output signal level was TTL instead of RS422.
Also works with my 7i95.

Hmmmmm....
I think it is time to do a fresh install from the 2.9.2 ISO and just installing the RTAI kernel and corresponding LinuxCNC.
You can probably install the kernel and LinuxCNC by just removing the existing LinuxCNC-uspace and installing with
sudo apt install linuxcnc

work perfectly, thank you