Hi Daniel,

It was done in a RTAI kernel-thread.
I had modified the example supplied by IgH Ethercat Master.
I had plugged a digital scope to see the jitter, while checking missing packets in dmesg. The goal was just to see how fast EtherCAT was.

best regards
---
Sebastien BLANCHET

On 03/08/2018 03:54 PM, PAUL-SOFTWARE wrote:
Hi Sebastien,

did you implement your code as a kernel-thread or as a rtai-userspace-process 
getting these results?

Mit freundlichen Grüßen / Best Regards

i.A. Daniel Koch

Elektronik/Software
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-----Ursprüngliche Nachricht-----
Von: etherlab-users [mailto:etherlab-users-boun...@etherlab.org] Im Auftrag von 
Sebastien Blanchet
Gesendet: Mittwoch, 14. Februar 2018 14:37
An: etherlab-users@etherlab.org
Betreff: Re: [etherlab-users] yet another datagrams UNMATCHED - DC 0.2ms / 5kHz 
// igb kernel 3.18

Hi Jürgen,

I can share with you some results with the 8139too and r8169 ethercat native 
drivers when used with RTAI and Preempt-RT kernel.

- with RTAI and 8139too you can achieve 10 KHz for the ethercat control loop 
without losing datagram. (tested on Debian 6.0 i386 with RTAI-3.8.1). The 
computer was a DELL Precision 390 with a Core Duo 2 processor, the slave were 4 
Beckhoff Ethercat terminals (EL1004, EL2004, EL3102, EL4102).

- with Preempt-RT and r8169 you can achieve 1 KHz for the ethercat control loop 
without losing datagram. (tested on Debian 7.0 i386 with Debian RT kernel).
At 2 KHz, it does not work very well (sometime you miss datagrams), so the 
limit is somewhere in the 1...2 KHz range. The computer is a Beckhoff 
C6920-0040 with the PCIe extension slots, and a Celeron B810 processor. The 
slaves are 4 Kollmorgen AKD servo drives + 13 other Ethercat terminals from 
Beckhoff.

Finally Preempt-RT is slower than RTAI, but it is really easier than RTAI.

best regards,
--
Sebastien BLANCHET




On 02/13/2018 02:12 PM, Christoph Schroeder wrote:
Hi Jürgen,

On 02/13/2018 10:01 AM, Jürgen Walter • DATATRONiQ wrote:
I see- will get another Intel card (although compatible ones (kernel driver
e1000, e1000e) seem to be hard to come by these days) and try with anther
kernel driver.
I also did some tests with the EtherCAT master, Xenomai and different network
devices compatible with the ec_e1000e driver.
Test system was a Core-i5 (4th generation) with a Debian Wheezy  (Kernel 3.2)
with two slaves attached (Microship LAN9252 in simple Digital I/O mode). I
observed the following:

   * even with the PREEMPT patch and the native driver ec_e1000e I could barely
     achieve 2000Hz cycle rate without frame losses
   * with Xenomai I could go over 10000Hz without a problem, but there are some
     other issues with Xenomai:
       o the EtherCAT master is not ready to use the newer Xenomai 3.x branch 
and
         the Xenomai 2.x branch is not supported anymore
       o I got some issues with long term stability on my test system (Kernel
         panic) and decided not to use it on a productive system
       o I would suggest you go for RTAI since you will also get far more help
         from the EtherCAT community, I could barely find other people here who
         also use Xenomai with the EtherCAT master
   * while using Xenomai I observed, that there is also a huge difference 
between
     different network chips:
       o I initially used a card with an Intel 82572EI (introduced Q4'05) and
         also tried a Dual port card with an Intel 82571EB (introduced Q3'05)
         which had basically the same results on my test system
       o the best results I got were achieved with an Intel 82574L (introduced 
Q2'0)

I didn't try RTAI till now, but I think you will get the same or even better
results than I got with Xenomai.

The cards with Intel 82574L we got were sold as "Intel Gigabit CT Desktop
Adapter". The chip will be produced until 2020, so getting a card with it should
be no problem. Maybe this will help you.


Best regards,
Christoph

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