[etherlab-dev] Possible Realtime Issues with Ethercat Master and RT Preempt Kernel

[Thomas Winding]

Hi Matthias Schöpfer

I have seen the same problem. I am also running at 1 ms and using clock_nanosleep.

 I suspect that the problem arise when you send a new telegram before you have received the previously send telegram.

Which version of the ethercat are you using?
Which version of kernel are you using?

Best regard,

Thomas Winding

-----Original Message-----
From: etherlab-dev [mailto:etherlab-dev-bounces at etherlab.org] On Behalf Of Dr.-Ing. Matthias Schöpfer
Sent: 26. januar 2016 14:22
To: etherlab-dev at etherlab.org
Subject: [etherlab-dev] Possible Realtime Issues with Ethercat Master and RT Preempt Kernel

Hi!

We started using etherlab/ethercat and are quite impressed. Nice work!

We are running Linux with a RT_PREEMPT Kernel and e1000e ethercat driver. We have to run at a cycle time of 1ms and we have jitter from clock_nanosleep of about 15 microsecs max.

Nevertheless, we suffer from time to time from these:

EtherCAT WARNING 0: 2 datagrams UNMATCHED!
EtherCAT 0: Domain 0: Working counter changed to 9/9.
EtherCAT 0: Domain 0: Working counter changed to 0/9.

Especially, when we apply load to the system. From previous projects, I experienced these effects when IRQ/Kernel Thread was not set to appropriate RT Level.

My Question: has anybody experienced similar problems, and would it be worth to investigate it. And if I decide to patch the kernel module, where is a good starting point.

Thanks and regards,

	Matthias Schöpfer

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Dr. Matthias Schöpfer
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