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  • andrax
  • andrax's Avatar
07 Apr 2026 13:01
Replied by andrax on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

Sorry,

It was just a thought. And no, I haven't had any jitter problems so far, despite endless restarts. I've often even had to restart the servos mid-operation (homing failure).
I'm absolutely certain that your driver is working and resolving the jitter issues.
But what if the hardware isn't compatible or is causing problems...?
I just wanted to throw that out there.

Sorry.
  • grandixximo
  • grandixximo's Avatar
07 Apr 2026 12:15
Replied by grandixximo on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

What are the clues supposed to point us to?
I have igc i210 advertised as supported by igh and Beckhoff.
There maybe a lot of reasons why your setup works for you, but there is only one cause for the jitter noise I was experiencing, there maybe other unrelated noises on other hardware, but the one I identified is fixed in my fork of the code.
What will figuring out why you don't have the issue get us? Did you run extensive testing with restarts looking at the halscope to prove you don't have the issue?
  • andrax
  • andrax's Avatar
07 Apr 2026 11:42
Replied by andrax on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

Interesting.
My computer is an ancient IPC from 2006. Except for the SSD, everything is original hardware.
The network card, however, has an Intel chip and is Beckhoff certified.

infosys.beckhoff.com/index.php?content=..../9309844363.html&id=

Perhaps that's a clue.
  • grandixximo
  • grandixximo's Avatar
07 Apr 2026 10:48 - 07 Apr 2026 11:27
Replied by grandixximo on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

The linuxcnc-ethercat current release does not respect the ethercat standard, it has time phasing issues, this is demonstrably true.
Anyone lucky enough to not experience any issue has:
Incredibly low latency
Servos that somehow adjust phasing themselves further than what the Ethercat standard dictates.
CPU with instruction execution timing consistency across processes, somehow doing the phasing properly even if the code did not directly intended it.
Some servo feature that filters the commanded position.
Not used pos-cmd mode.
Not actively been looking for it, restarting 100+ times and induced high latency, and looking at Ferror and servo-thread in the halscope.

Even if some hardware is not bothered by wrong phasing, you should not blame this on the servo drives manufacturers. The software they are interfacing with demonstrably does NOT respect the communication standard.
  • Todd Zuercher
  • Todd Zuercher's Avatar
07 Apr 2026 10:15 - 07 Apr 2026 13:19
Replied by Todd Zuercher on topic Homing To Index Following Error

Homing To Index Following Error

Category: Advanced Configuration

It's the current release 2.9.7

(Edit)
Had to go look at what was actually on the machine, and it's 2.9.8 running on Debian Trixi.
  • grandixximo
  • grandixximo's Avatar
07 Apr 2026 09:37
Replied by grandixximo on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

I've used LeadShine and XingJie same issues with both, there may well be mitigations on the servos side for some manufacturer, but that does not mean the standard of Ethercat says they should be doing such a thing. So it's luck?
  • dredivan
  • dredivan
07 Apr 2026 08:35 - 08 Apr 2026 14:14
Rotary axis backplot — centre of rotation not following WCS offset was created by dredivan

Rotary axis backplot — centre of rotation not following WCS offset

Category: General LinuxCNC Questions

 
Hi,

I have a 4-axis MPCNC with a rotary B axis mounted at the far end of the Y travel (machine Y=700mm). The rotary axis is fixed — it does not move along Y.

G-code is generated by CAM with program zero at the chuck face, all moves go in Y-.

The problem: the backplotter does not display the toolpath correctly. Instead of showing the wrapped toolpath around the tube near the chuck, it draws a large circle. I believe this happens because the backplotter uses machine zero as the centre of rotation rather than the actual chuck position.

Setup:
- LinuxCNC 2.9.8 stable
- trivkins coordinates=XXYYZB, 6 joints
- qtdragon_hd interface
- GEOMETRY = !-BXYZ

Is there any way to tell the backplotter where the centre of rotation is?
[DISPLAY]
DISPLAY = qtvcp qtdragon_hd
# qtdragon saves most preference to this file
PREFERENCE_FILE_PATH = WORKINGFOLDER/qtdragon.pref



POSITION_OFFSET = RELATIVE
POSITION_FEEDBACK = ACTUAL
MAX_FEED_OVERRIDE = 2.000000

MAX_SPINDLE_0_OVERRIDE = 1.5
MIN_SPINDLE_0_OVERRIDE = .5
DEFAULT_SPINDLE_0_SPEED   = 12000

# spindle up/down increment in RPM
SPINDLE_INCREMENT = 200

# min max apindle speed manually allowed 
MIN_SPINDLE_0_SPEED = 1000
MAX_SPINDLE_0_SPEED = 20000
# max spindle power in Watts
MAX_SPINDLE_POWER = 2000

#MAX_SPINDLE_OVERRIDE = 1.000000
#MIN_SPINDLE_OVERRIDE = 0.500000

INTRO_GRAPHIC = linuxcnc.gif
INTRO_TIME = 5
#PROGRAM_PREFIX = /home/user/linuxcnc/nc_files
PROGRAM_PREFIX = /home/user/cnc-programs
INCREMENTS = 5mm 1mm .5mm .1mm .01mm 
ANGULAR_INCREMENTS = 1, 5, 10, 30, 45, 90, 180, 360
POSITION_FEEDBACK = ACTUAL
DEFAULT_LINEAR_VELOCITY = 40.000000
MAX_LINEAR_VELOCITY = 100.000000
MIN_LINEAR_VELOCITY = 0.500000
DEFAULT_ANGULAR_VELOCITY = 12.000000
MAX_ANGULAR_VELOCITY = 180.000000
MIN_ANGULAR_VELOCITY = 1.666667
EDITOR = gedit
GEOMETRY = !-BXYZ
CYCLE_TIME = 100
  • Hakan
  • Hakan
07 Apr 2026 08:32
Replied by Hakan on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

Theoretically the problem is there. 
Some drives may be better than others to conceal the problem.
When you use syncToRefClock and don't hear it you will not hear it.
I mean the drives will not suddenly start being noisy.
The chance of hearing it is roughly every servo loop time/jitter start of linuxcnc.
With 7 microseconds jitter, you can hear it every 142'nd start of linuxcnc.
And you hear it throughout the linuxcnc session.

I thought my drives were immune to this, but after carefully listening I found they also
experience this, but they don't sound awful, just a very mild "tic".
The drives don't have to make noises, but they should definitely react to it.
It's basically a disturbance in the position flow, requesting an artificially very high or low acceleration.
  • rodw
  • rodw's Avatar
07 Apr 2026 07:53
Replied by rodw on topic LinuxCNC not working with new 64-bit desktop and parallel port

LinuxCNC not working with new 64-bit desktop and parallel port

Category: General LinuxCNC Questions

This rang a bell from when I wrote a terminate-and-stay-resident PC-DOS (stop laughing) program that intercepted data.

I did something similar but it trickled point of sale transactions out of a cash register to accounting software (And I got paid for it!)
  • rodw
  • rodw's Avatar
07 Apr 2026 07:49
Replied by rodw on topic Ethercat random jitter fix

Ethercat random jitter fix

Category: EtherCAT

I’ve been following this thread with interest all along. What surprises me, though, is that I haven’t experienced the jitter issues described so far. I’d be interested to know what hardware you’re using. Perhaps there’s a correlations 

Its never been an issue for me  either. I did wonder the other day if newer hardware was  not a concern.
  • meister
  • meister
07 Apr 2026 07:39
Replied by meister on topic LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

Category: Computers and Hardware

soooooo, dev is merged to main, no way back :)

there are some big changes:

### Warning
* breaking changes, please open your config in rio-flow to fix/convert some stuff

### Gui
* new graphical config-gui: rio-flow
* removing old rio-setup

### Genaral
* move all stuff into plugins (boards/modules/breakouts)
* replacing modbus -> mbus/mbus_device/mbus_hy
* replacing i2cbus -> i2c/i2c_device
* better simulation
* test-tool is now based on the hal-component c-code
  • opw
  • opw
07 Apr 2026 07:11
Replied by opw on topic Simple G7x Profile editor for Linuxcnc/Axis

Simple G7x Profile editor for Linuxcnc/Axis

Category: AXIS

Thanks for reporting this. I am a little pressed for time these days, so I don't know when I get around to checking and fixing it. 

 
  • meister
  • meister
07 Apr 2026 06:38
Replied by meister on topic Raspberry with LinuxCNC direct interface

Raspberry with LinuxCNC direct interface

Category: Computers and Hardware

Untested

 

 

File Attachment:

File Name: rpi4-stepper.zip
File Size:598 KB
  • Tserakhau
  • Tserakhau
07 Apr 2026 06:36
Replied by Tserakhau on topic Retrofitting a 1986 Maho MH400E

Retrofitting a 1986 Maho MH400E

Category: Milling Machines

  Good afternoon.My name is Victor, and I'm restoring a MAHO 600E milling machine and converting it to Linux (the original Philips operating system).Thank you so much for this thread; many questions were resolved using the forum.I received the machine without a spindle motor, coolant system, and most relays.I've already done almost everything; the machine moves and finds its home position.I installed and tested the speed control box; all speeds shift perfectly! (The box is completely identical to yours, although the motors are installed slightly differently.)I've also already configured the lubrication system, hydraulic clamp, and MPG control panel.My question is: what needs to be done next after setting up the simulator? How do I implement this into the .ini or .hal files?I apologize for any inaccuracies in the text of this message; I'm using Google Translate because my English is poor.
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