[etherlab-users] AL status message 0x0036: "DC Sync0 Cycle Time"

Jürgen Walter • DATATRONiQ jw at datatroniq.com
Mon Apr 2 19:15:04 CEST 2018 

Hi Mike,

glad to hear you got it working. Can you please clarify:

> I wanted to thank you all for your valuable advice. Now I'm acheiving 
> near 3.5 kHz loop rate without a single datagram loss. My configured 
> system is
are you still trying to go for 5-10kHz (as per your initial e-mail)?

> Ubuntu 16.04 with kernel 4.8.15-rt10 (preempt_rt patched)
did you compile this yourself or did you find a low latency / preempt 
version in the Ubuntu repos?

> and support for native driver.
what do you mean by "native driver" - is this the generic driver?

Finally, do you mind writing a short list of commands (while the memory 
is still fresh ;) ) for us and for your future self, perhaps:

1. built the custom kernel 4.8.x for preempt_rt
2. built etherlab, ie `./configure --options ....`

Thank you! Jürgen


On 2 Apr 2018, at 18:19, Mike Karam wrote:

> Hi all,
>
> I wanted to thank you all for your valuable advice. Now I'm acheiving 
> near 3.5 kHz loop rate without a single datagram loss. My configured 
> system is (just for reference): Ubuntu 16.04 with kernel 
> 4.8.15-rt10(preempt_rt patched) and support for native driver. I would 
> like to ask another question: In the dc_user example I don't 
> understand why the latency is measured that way. Could someone make it 
> more clear? This latency is the latency of our application (the time 
> the scheduler does to put our process to running, so that our 
> application can process the newly arrived datagram)? What quantity is 
> measured exactly with this latency? Bonus: Can we measure the time the 
> datagram does to leave and come back to  the master, with wireshark 
> accurately?
>
> Thank you in advance,
> Mike Karam
>
> Στις Πέμ, 8 Μαρ 2018, 5:37 μ.μ. ο χρήστης Mike 
> Karam <mike95gr at hotmail.com<mailto:mike95gr at hotmail.com>> 
> έγραψε:
> Hi Martin,
>
> thanks for the advice. It seems to me that the hard real time 
> RT-Preempt patch
> cannot be avoided if I want to achieve my goal. I will keep that in 
> mind and probably
> come back to that.
>
> Thanks again,
> Mike
>
>
> ________________________________________
> Από: Mike Karam <mike95gr at hotmail.com<mailto:mike95gr at hotmail.com>>
> Στάλθηκε: Πέμπτη, 8 Μαρτίου 2018 5:09 μμ
> Προς: Jürgen Walter • DATATRONiQ
> Κοιν.: 
> etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
> Θέμα: Απ: [etherlab-users] AL status message 0x0036: "DC Sync0 
> Cycle Time"
>
> Hi Jurgen,
>
> thanks for your reply. I forgot to mention that I'm running the 
> lowlatency package of kernel 4.8.0-58. The thing is that,
> the team wants 16.04 Ubuntu because of the ROS Kinetic development, so 
> I don't think I can use
> a 3.x kernel (although last time I checked there is also a 4.x 
> PREEMPT_RT patch also). I didn't think that
> soft-real time vs hard-real time makes such a difference. I will try 
> and come back on that.
> Another observation of mine is that using Wireshark, the time the 
> datagrams left and the time the datagrams came couldn't
> get less than 240 μs. Shouldn't the DC use of the master, change this 
> time difference  to something very small (e.g 100,50,20 μs),
> till there is synchronization loss or packet loss?
>
> Thanks again,
> Mike
>
> ________________________________________
> Από: Jürgen Walter • DATATRONiQ 
> <jw at datatroniq.com<mailto:jw at datatroniq.com>>
> Στάλθηκε: Πέμπτη, 8 Μαρτίου 2018 4:21 μμ
> Προς: Mike Karam
> Κοιν.: 
> etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
> Θέμα: Re: [etherlab-users] AL status message 0x0036: "DC Sync0 
> Cycle Time"
>
> Hi Mike,
>
> I was in a similar boat like you just not too long ago. So, first 
> thing,
> you need to get your Linux system "real-time" --> best to use 
> PREMPT_RT
> in the vanilla Kernel.
>
> That said, for using DC and > 1kHz I never got the "generic" driver to
> work. How about you downgrade to a 3.x kernel, e.g. 3.18 and use one 
> of
> the supported drivers w/ patches for RT operation. That is what I did 
> -
> I also bought a network interface card with a supported chipset and
> installed that into a PCIe slot.
>
> Since then, I am pretty much a happy camper.
>
> I hope this helps. Jürgen
>
> On 8 Mar 2018, at 14:23, Mike Karam wrote:
>
>> Hi,
>>
>> I'm trying to create an EtherCAT communication with an XMC4800, using
>> IgH EtherCAT. I'm using 16.04 Ubuntu with 4.8.0-58 kernel. I
>> downloaded the code from sourceforge and run the code (a bit 
>> modified,
>> see attachment) found in examples/dc_user. If I use a loop frequency
>> of 1 KHz all things go well (despite some datagrams UNMATCHED
>> warnings). But if I increase the loop rate to 5 or 10 KHz I'm seeing
>> the error in the subject. My goal is at least 10Khz succesful 
>> (withoul
>> losses) communication. Below is the output I'm getting in the kernel
>> log:
>>
>>
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296909] EtherCAT: Requesting master 0...
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296912] EtherCAT: Successfully requested master 0.
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296961] EtherCAT 0: Domain0: Logical address 0x00000000, 18
>> byte, expected working counter 3.
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296962] EtherCAT 0:   Datagram domain0-0-main: Logical offset
>> 0x00000000, 18 byte, type LRW at ffff91a5b5c9d858.
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296981] EtherCAT 0: Master thread exited.
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.296983] EtherCAT 0: Starting EtherCAT-OP thread.
>> Mar  8 14:42:31 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13658.297040] EtherCAT WARNING 0: 15 datagrams UNMATCHED!
>> Mar  8 14:42:32 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13659.296406] EtherCAT WARNING 0: 13437 datagrams UNMATCHED!
>> Mar  8 14:42:32 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13659.297430] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 6725 times.
>> Mar  8 14:42:33 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13660.296475] EtherCAT WARNING 0: 13455 datagrams UNMATCHED!
>> Mar  8 14:42:33 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13660.298486] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 6734 times.
>> Mar  8 14:42:34 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13661.296543] EtherCAT WARNING 0: 13442 datagrams UNMATCHED!
>> Mar  8 14:42:34 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13661.299562] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 6726 times.
>> Mar  8 14:42:35 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13662.296611] EtherCAT WARNING 0: 13388 datagrams UNMATCHED!
>> Mar  8 14:42:35 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13662.300630] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 6700 times.
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.296679] EtherCAT WARNING 0: 13414 datagrams UNMATCHED!
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.301699] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 6715 times.
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.310699] EtherCAT WARNING 0-0: Slave did not sync after 5000 
>> ms.
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.312411] EtherCAT ERROR 0-0: Failed to set SAFEOP state, slave
>> refused state change (PREOP + ERROR).
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.312949] EtherCAT ERROR 0-0: AL status message 0x0036: "DC 
>> Sync0
>> Cycle Time".
>> Mar  8 14:42:36 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13663.313501] EtherCAT 0-0: Acknowledged state PREOP.
>> Mar  8 14:42:37 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13664.296893] EtherCAT WARNING 0: 14550 datagrams UNMATCHED!
>> Mar  8 14:42:37 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13664.302791] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7285 times.
>> Mar  8 14:42:38 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13665.296872] EtherCAT WARNING 0: 14323 datagrams UNMATCHED!
>> Mar  8 14:42:38 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13665.303849] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7165 times.
>> Mar  8 14:42:39 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13666.296910] EtherCAT WARNING 0: 14357 datagrams UNMATCHED!
>> Mar  8 14:42:39 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13666.304931] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7184 times.
>> Mar  8 14:42:40 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13667.296989] EtherCAT WARNING 0: 14185 datagrams UNMATCHED!
>> Mar  8 14:42:40 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13667.305995] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7104 times.
>> Mar  8 14:42:41 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13668.297188] EtherCAT WARNING 0: 14166 datagrams UNMATCHED!
>> Mar  8 14:42:41 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13668.307062] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7085 times.
>> Mar  8 14:42:42 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13669.297098] EtherCAT WARNING 0: 14209 datagrams UNMATCHED!
>> Mar  8 14:42:42 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13669.308106] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7112 times.
>> Mar  8 14:42:43 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13670.297189] EtherCAT WARNING 0: 13986 datagrams UNMATCHED!
>> Mar  8 14:42:43 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13670.309191] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7005 times.
>> Mar  8 14:42:44 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13671.297272] EtherCAT WARNING 0: 14235 datagrams UNMATCHED!
>> Mar  8 14:42:44 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13671.310255] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7122 times.
>> Mar  8 14:42:45 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13672.297425] EtherCAT WARNING 0: 14340 datagrams UNMATCHED!
>> Mar  8 14:42:45 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13672.311322] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7185 times.
>> Mar  8 14:42:46 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13673.297404] EtherCAT WARNING 0: 14455 datagrams UNMATCHED!
>> Mar  8 14:42:46 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13673.312406] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7227 times.
>> Mar  8 14:42:47 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13674.297464] EtherCAT WARNING 0: 14545 datagrams UNMATCHED!
>> Mar  8 14:42:47 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13674.313523] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7281 times.
>> Mar  8 14:42:48 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13675.297525] EtherCAT WARNING 0: 14760 datagrams UNMATCHED!
>> Mar  8 14:42:48 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13675.314541] EtherCAT WARNING: Datagram ffff91a5b5c9d858
>> (domain0-0-main) was SKIPPED 7384 times.
>> Mar  8 14:42:49 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13676.202128] EtherCAT 0: Releasing master...
>> Mar  8 14:42:49 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13676.202166] EtherCAT 0: Master thread exited.
>> Mar  8 14:42:49 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13676.202179] EtherCAT 0: Starting EtherCAT-IDLE thread.
>> Mar  8 14:42:49 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13676.202260] EtherCAT 0: Released.
>> Mar  8 14:42:49 mikekaram-HP-EliteBook-Folio-9470m kernel:
>> [13676.202274] EtherCAT ERROR 0-0: Failed to receive AL state
>> datagram: Datagram initialized.
>>
>>
>> What am I doing wrong? Could you please offer me some advice, to
>> achieve my goal?
>>
>> Regards,
>>
>> Mike Karamousadakis
>> _______________________________________________
>> etherlab-users mailing list
>> etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
>> http://lists.etherlab.org/mailman/listinfo/etherlab-users
>
>
> _______________________________________________
> etherlab-users mailing list
> etherlab-users at etherlab.org
> http://lists.etherlab.org/mailman/listinfo/etherlab-users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.etherlab.org/pipermail/etherlab-users/attachments/20180402/c4038c02/attachment-0003.htm>

More information about the Etherlab-users mailing list