[etherlab-dev] Datagram SKIPPED x Times

[Mike O'Connor]

Hi Andreas

Yep 4K is no problem is higher that is a problem. We have 2 bus couplers
in a daisy chain on my test rig, and 4 IO modules.

I'll try a different card soon, but I've used both the generic and non
generic Intel drivers with no different in the possible rates.

4K works great doubling it to 8K the SKIPPED goes though the roof, as I
said I've confirmed the bus coupler is not an issue the issue is the PC
not doing the right thing with the packets.

I just really want to now what sort of rate could be achievable with
etherlab. The packet captures I've seen seem to indicate that the bus
couplers are able to run a very high rate. (ie at least 25K)

Mike


On 21/03/12 11:13 PM, Andreas Stewering-Bone wrote:
> Hello Mike,
>
> The max rate depends on your bus topology (Number of Slaves, Number of
> EKXXX modules).
> Generally 4K should be no problem.
>
> But if you have the possibility, please do not use Intel cards, try a
> stupid Realtek card.
> Intel cards are known to have some freatures which can make some
> trouble at higher rate.
>
> Do not use the generic interface for such rates, please use the native
> drivers.
>
> Greatings
>
> Andreas
>
> Am 21.03.2012 13:25, schrieb Mike O'Connor:
>> Hi All
>>
>> I have been testing with Etherlab and a small number of Beckhoff Digital
>> IO, the Ethercat (not Etherlab) technical data seems to indicate that an
>> updates at a rate of at least 30 micro seconds for up to 1000 IO points
>> (possibly faster for smaller numbers) is possible.
>>
>> I adjusted the user land examples to work with our IO and then started
>> increasing the frequency and found that at 4K I get no issue (maybe a
>> couple of the dmesg messages below at the start)
>>
>> [  412.872048] EtherCAT WARNING: Datagram f6bbfc00 (domain0-0) was
>> SKIPPED 6 times.
>>
>> but as I increase the rate to 8K then 12K and finally 25K the number of
>> SKIPPED gets larger and larger
>>
>> [173178.785515] EtherCAT WARNING: Datagram f6851360 (domain0-0) was
>> SKIPPED 43476 times.
>>
>> I did adjust the intel GigE driver (e1000e) to use a
>> InterruptThrottleRate of 0 which helped a lot with consistency. I also
>> tried the non generic drive with no change in the above messages.
>>
>> I've confirmed via a mirror port on a switch and a capture of the
>> packets that the IO is replying to every packet we send and that the
>> rate of sending would seem to match the 8K, 12K, and 25K.
>>
>> This seems to indicate to me that the issue is in the Ethercat master,
>> is etherlab up to the task of running a high scan rate ?
>>
>> Thanks
>> Mike
>>
>> _______________________________________________
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>> etherlab-dev at etherlab.org
>> http://lists.etherlab.org/mailman/listinfo/etherlab-dev
>>    
>
>
> Mit freundlichem Gruß
>
> Andreas Stewering-Bone
>

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