Multiple controller boards

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13 Nov 2024 20:17 #314402 by AA
Greetings,
I'm wondering,  it's it possible to connect a couple of controller boards  (like Arduino) to LinuxCNC, i.e.one for XYZ, anothe for ABC, one more for adding a turret or a double spindle..?

Why not, it seems to me there must be a way now as computers got super processing powers.

If yes, is there a specific controller board type(s) that can be connected together? Maybe several types may inter communicate with LinuxCNC and to themselves too?

Or maybe connect a number of these boards to a number of servo motors and drivers and other boards to other stepper motors and drivers?

Exactly, I am just at a beginner, trying to figure out how to make my super fancy machine., so do you think my dreams are valid, or can be true soon?
Is there some hardware that I have to buy prior to others, you know in order to plan the priorities and budget, but make sure I want to build the fancy CNC?

I'm sure there are many like me.

Thanks,,
Byes

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13 Nov 2024 20:37 - 13 Nov 2024 20:38 #314406 by tommylight
Mesa 7i96S as the first in line, all in one, then to move things along, Mesa 7i85 for encoders and Smart serials, then add 7i84 or 7i70 or 7i71 for IO as these can be remote to any place on the machine and require only a single LAN cable to communicate.
Mesa boards start at something like 70$ and up, they are very fast and very reliable and i have used a lot of those on industrial machines that are in use daily.
Anything else you look might seem cheaper, it is not, and they will be extremely limited in expansion compared to Mesa.
You can probably do this cheaper with Remora boards or ESP32, but to much fuss and messy wiring and to much time compiling/configuring stuff just to make them work.
BTW, i did test ESP32 and it works, and i can build any damn thing i need, but the time and effort is not worth at all compared to Mesa "wire it/power it/run the machine."
Last edit: 13 Nov 2024 20:38 by tommylight. Reason: typo
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14 Nov 2024 11:41 #314435 by Tinine
Replied by Tinine on topic Multiple controller boards

Anything else you look might seem cheaper, it is not, and they will be extremely limited in expansion compared to Mesa.

 

Trying to get a feel for this but I'm a bit overwhelmed.
Is it possible to use my own motion controller with LinuxCNC? I am only interested in closed-loop servo and I want to handle the PID myself. 

Craig
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14 Nov 2024 14:21 #314448 by tommylight
What do you mean by Motion Controller?
Using 2 of those would be reduntant and unnecessary.
Do you mean closed loop in the drive or in LinuxCNC? Both can be used, and LinuxCNC has PID controll and settings for everything required. Also can use PID closed in Drives and in LinuxCNC, and much more.

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14 Nov 2024 14:31 #314449 by Tinine
Replied by Tinine on topic Multiple controller boards
I have created closed-loop motion controllers using the RPi Pico, each one reading 4 quadrature encoders (2.8M quad-counts/sec)
I am using a separate Pico for each axis though. +/- 10V motor command, 12-bit DAC.
I guess I could simply take pulse & direction from LinuxCNC but I would like to not have to worry about LC's latency and jitter issues.

Craig

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14 Nov 2024 14:53 #314453 by tommylight
That would be analog control, like old servo drives or velocity control drives, so yes you can control them with LinuxCNC and Mesa boards, see below, and would also require encoder feedback to LinuxCNC.
Mesa combos that can do +-10V :
7i97T all in one
7i92TM with 7i77
7i92TM with 7i85 and 7i83 and 7i84 for IO if needed
7i96S with 7i85 and 7i83.

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14 Nov 2024 15:42 #314459 by Tinine
Replied by Tinine on topic Multiple controller boards
Yeah I understand this but I want to use my own controllers and my own PID, etc. 

I don't want to rely on an OS for the motion control. Is this even an option with LinuxCNC?

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14 Nov 2024 15:59 #314460 by tommylight

Yeah I understand this but I want to use my own controllers and my own PID, etc. 

That is all good as explained (i tried) above.

I don't want to rely on an OS for the motion control. Is this even an option with LinuxCNC?

This makes no sense as LinuxCNC is a Motion Controller that runs inside an OS, Linux in this case.
I think i might be on the right track as to what you are looking for, but first some stuff to get out of the way
-you have drives with PID loop in them, they are not motion controllers
-motion controller in this context implies opening gcode, parsing it, planing the trajectory for the axis/joints, sending understandable signals to drives/outside world.
-
You can use separate parts of LinuxCNC on their own, mostly, so you can probably use the gcode parser and trajectory planner, but you would also need the sending signals to drives part, so......
any closer?

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14 Nov 2024 16:10 #314462 by Tinine
Replied by Tinine on topic Multiple controller boards
Yes and no...LOL.

For decades now, my servo drives are configured for torque commands, aka "transconductance"
I develop my own motion controllers that handle PID VFF, AFF, dual-loop feedback, etc., etc.
My latest is using the $10 RPi Pico. Using the PIO state machines, I decode the quadrature with zero impact on the two MCU cores.
Ideally, I'd like LinuxCNC to be the G-Code processor, etc. and take care of the time critical stuff in the Picos.
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14 Nov 2024 16:24 - 14 Nov 2024 16:29 #314464 by PCW
Replied by PCW on topic Multiple controller boards
LinuxCNC is the  (real time)  motion controller that takes gcode or manual commands
an converts them to constrained (velocity, acceleration. position) per joint motion data.
LinuxCNC also gets real time feedback from motion hardware to allow for spindle synchronized
motion for things like threading and rigid tapping.

 
How this data is conveyed to/from motion hardware depends on the actual motion hardware
(analog,step/dir,EtherCAT, modbus,pwm, quad encoder, absolute encoder, resolver etc etc)

Sounds like you want something more like Mach, that buffers motion commands in an external controller
 
Last edit: 14 Nov 2024 16:29 by PCW.
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