Ethercat random jitter fix

rodw
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17 Apr 2026 12:33 #345633 by rodw

Replied by rodw on topic Ethercat random jitter fix

Hakan wrote:
I tried to compile 1.5.2 on trixie but easier said than done. While I could get around several configuration issues,
there were in the end too severe compilation problems (for me) that I gave up.
At least 1.5.2 doesn't compile out-of-the-box on trixie.
 

This does not surprise me. I found over the years of keeping repositories in sync, Ethercat includes dkms code which is tailored for specific kernels and breaks with the release of new versions of Debian. This did happen again with the release of Trixie but etherlab expedited the release of 1.6 on my request so you guys probably never noticed. Also, 1.6 is much more sensitive to secure boot and this requires authorizing dkms to modify the kernel code.

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grandixximo
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17 Apr 2026 13:36 #345639 by grandixximo

Replied by grandixximo on topic Ethercat random jitter fix

gitlab.com/grandixximo/ethercat/-/jobs/1...ad?file_type=archive

Here have debs of ethercat 1.5.2 compatible with debian 13

github.com/grandixximo/linuxcnc-ethercat...0.9.5-retro1.5.2-rc1

and here a linuxcnc-ethercat compatible with the 1.5.2 retro release

you need to type in the mac address and use generic in the systemconfig/ethercat file, in my test OP is same speed, please test on your end and let me know.

linuxcnc-ehtercat retro version I only tweaked latest version based on Sascha's work, and did minimal changes to be compatible with retro 1.5.2 ethercat

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grandixximo
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17 Apr 2026 13:47 #345640 by grandixximo

Replied by grandixximo on topic Ethercat random jitter fix

@Hakan @papagno-source
I get worse OP times with 1.5.2
Is that the case for you as well?
Do you have a kernel + linuxcnc + linuxcnc-ethercat + ethercat
versions combination that gets everything ready sub 1 sec?
Before axis opens or just as axis UI opens up?

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papagno-source
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17 Apr 2026 15:37 #345643 by papagno-source

Replied by papagno-source on topic Ethercat random jitter fix

Syste is debian 10 buster x86_64
Kernel: 4.19.0-27-rt-amd64 #1 SMP PREEEMPT RT Debian 4.19.316-1 (2024-06-25) x86_64 GNU/Linux
Ethercat : IgH ETHERCAT master 1.5.2 unknow
Etherlabmaster-1.5.2+20190904hg33b922p8ea394
LINUXCNC 2.9.0-pre0

When axis opens the gui, the axis dimensions are already present. From tests done, when I had the same problem with debian 12, as soon as it reads the loadrt lcec command, the dimensions appear on the pins in hal, relating to the individual axes.

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papagno-source
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17 Apr 2026 16:22 - 17 Apr 2026 16:37 #345644 by papagno-source

Replied by papagno-source on topic Ethercat random jitter fix

I have installed linuxcnc-ethercat...0.9.5-retro1.5.2-rc1, without error, but if coomand ethercat version have reult 1.6.9
But I think, this is not the Igh part, but the lcec driver, right?
I have a version running in place in another directory, do I need to copy or link something to test?
On Debian 10 , in direcory bin the linuxcnc , i have only lcec_conf and not have lcec_coffingen

Last edit: 17 Apr 2026 16:37 by papagno-source.

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Hakan
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17 Apr 2026 16:48 #345645 by Hakan

Replied by Hakan on topic Ethercat random jitter fix

Tested a bit.
I get fairly consistent loading times of lcec's rt_app_main() function of 1.85-1.90 seconds.
But but. In syslog I can see that the initial sync of slaves takes anywhere between zero and
say 3,4,5 seconds.
To check
ethercat debug 1
start linuxcnc
exit or leave running, doesn't matter.
sudo journalctl --since "2 minutes ago" | grep "Sync after"
and see where it stops for every slave.
I reckon this is the problematic delay time.
Seldom, but it happens, I get "Checking for synchrony" and then it is satisfied directly and moves on.

It seems measuring the time of lcec's rt_app_main is not a good indicator.
Is there a good way of measuring time to OP?

trixie,
Linux plasma 6.12.69+deb13-rt-amd64 #1 SMP PREEMPT_RT Debian 6.12.69-1 (2026-02-08) x86_64 GNU/Linux
IgH EtherCAT master 1.6.8 1.6.8.g2543cc5-1+27.3 (via apt)
linuxcnc-ethercat, a slightly modified version of commit bf13577ec7b1b54844e07a80d949232e71776b32
linuxcnc 2.9.4 (via apt)

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grandixximo
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18 Apr 2026 00:21 #345665 by grandixximo

Replied by grandixximo on topic Ethercat random jitter fix

papagno-source wrote:
Syste is debian 10 buster x86_64
Kernel: 4.19.0-27-rt-amd64 #1 SMP PREEEMPT RT Debian 4.19.316-1 (2024-06-25) x86_64 GNU/Linux
Ethercat : IgH ETHERCAT master 1.5.2 unknow
Etherlabmaster-1.5.2+20190904hg33b922p8ea394
LINUXCNC 2.9.0-pre0

When axis opens the gui, the axis dimensions are already present. From tests done, when I had the same problem with debian 12, as soon as it reads the loadrt lcec command, the dimensions appear on the pins in hal, relating to the individual axes.

linuxcnc-ethercat version?

dpkg -l | grep linuxcnc-ethercat

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grandixximo
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18 Apr 2026 00:37 #345666 by grandixximo

Replied by grandixximo on topic Ethercat random jitter fix

papagno-source wrote:
I have installed linuxcnc-ethercat...0.9.5-retro1.5.2-rc1, without error, but if coomand ethercat version have reult 1.6.9
But I think, this is not the Igh part, but the lcec driver, right?
I have a version running in place in another directory, do I need to copy or link something to test?
On Debian 10 , in direcory bin the linuxcnc , i have only lcec_conf and not have lcec_coffingen

gitlab.com/grandixximo/ethercat/-/jobs/1...ad?file_type=archive
This is the igh ethercat, you need to uninstall your current ethercat master to get this to work, also ethercat-dkms and libethercat.
You might have to run or restart the ethercat service after installing the deb packages in the artifact.zip

sudo systemctl restart ethercat.service

for the linuxcnc-ehercat remove your current version
and install this
github.com/grandixximo/linuxcnc-ethercat...0.9.5-retro1.5.2-rc1
this is the lcec part, and it has both lcec_conf and lcec_coffingen
I cannot fathom why you would have one and not the other if you installed my packages.

I saw you tried to come to the discord, but you did not give a thumbs up to the rules message, so you were not allowed in.

I'm on +08:00 time. not in Italy. So mind the time difference. I'll only probably be available in the morning Italy time.

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rodw
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18 Apr 2026 00:49 #345668 by rodw

Replied by rodw on topic Ethercat random jitter fix

For somebody trying hard to follow along from the sidelines, can you guys outline the objective for rolling back to 1.52 here?
Has anybody looked at the Igh Ethercat master 1.6 or even 1.7 which was released on gitlab 3 weeks ago (but not in their repositories) to see if it has these delays outside of linuxcnc.

It seems to me it would be unlikely that iGh master 1.6 or 1.7 are problematic as people would be complaining at iGh so to me, the effort should be in understanding what has changed that linuxcnc-ethercat is not liking. Rolling back to a very old version does not seem a progressive step following the synchronisation enhancement.

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grandixximo
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18 Apr 2026 01:17 - 18 Apr 2026 01:20 #345669 by grandixximo

Replied by grandixximo on topic Ethercat random jitter fix

Hakan wrote:
Tested a bit.
I get fairly consistent loading times of lcec's rt_app_main() function of 1.85-1.90 seconds.
But but. In syslog I can see that the initial sync of slaves takes anywhere between zero and
say 3,4,5 seconds.
To check
ethercat debug 1
start linuxcnc
exit or leave running, doesn't matter.
sudo journalctl --since "2 minutes ago" | grep "Sync after"
and see where it stops for every slave.
I reckon this is the problematic delay time.
Seldom, but it happens, I get "Checking for synchrony" and then it is satisfied directly and moves on.

It seems measuring the time of lcec's rt_app_main is not a good indicator.
Is there a good way of measuring time to OP?

trixie,
Linux plasma 6.12.69+deb13-rt-amd64 #1 SMP PREEMPT_RT Debian 6.12.69-1 (2026-02-08) x86_64 GNU/Linux
IgH EtherCAT master 1.6.8 1.6.8.g2543cc5-1+27.3 (via apt)
linuxcnc-ethercat, a slightly modified version of commit bf13577ec7b1b54844e07a80d949232e71776b32
linuxcnc 2.9.4 (via apt)

At the end of my hal file I

loadusr halshow

and I save the default watch to display the OP pins, you can have master all-op, and each slave individual OP pin, I count Mississippies or use stopwatch...
Another alternative is

watch -n 0.2 ethercat sl

But this might "dirty" the bus, may effect OP time, maybe...
To get more accurate times might have to build a script, or use dmesg with some debug from ethercat.
But I think the difference papagno-source is talking about can be perceived with less precise tooling, in one case everything OP even before the UI opens, and in the other he has to wait some amount of time, so it is a difference in the seconds range.
I will try to setup similar setup to yours, and check the OP times.

Last edit: 18 Apr 2026 01:20 by grandixximo.

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