[etherlab-users] EtherCAT Master via USB-Adapter?

Karl Zeilhofer karl at zeilhofer.co.at
Fri May 3 00:01:27 CEST 2019


Dear Mr. Hagemeister,

today I've got my first demo-application up and running on Linux Mint
19.1 without any realtime patches.

As a first try I used the default ethernet driver (even though it's an
e1000e NIC).

It was much easier, than I expected. The program runs quite stable with
a 1ms cycle period.

I will let you know about the tests with the USB-adapter, when it has
been arrived. I will do them on a
Debian 9 with PREEMT_RT.

Do you have any recommendations for testing the jitter? Currently I made
a hardware loopback from an
output to an input, and negating the signal in the control program. With
my setup (EK1004 and EK2008) this
results in a period of the oscillation of 8ms. With the oscilloscope I
measured that period, and the according statistics (mean, min, max).

Kind regards,
Karl Zeilhofer

On 30.04.19 10:00, Dr.-Ing. Wilhelm Hagemeister wrote:
> Hallo Mr Zeilhofer,
>
> with a good tuned system and native driver one can realize sample rates
> up to several kHz with jitter at some micro seconds. As far as I know
> USB gets polled by the kernel. I would expect it can be used in a sample
> rate range up to 100 Hz but we have no experience jet. May you can
> discover and post your results here?
>
> Regards Wilhelm.
>
> Am 30.04.2019 um 09:49 schrieb Karl Zeilhofer:
>> Dear Mr. Wilhelm,
>>
>> thanks for your first advices. May I ask, what do you define as "good"
>> realtime behavior?
>>
>> Could this "bad" realtime performanc be improved by using a USB-adapter
>> with a supported chipset? Or does USB (3.0) introduce inherently bad
>> realtime performance?
>>
>> Kind regards, Karl Zeilhofer
>>
>>
>> On 30.04.19 07:47, Dr.-Ing. Wilhelm Hagemeister wrote:
>>> Hallo Mr Zeilhofer,
>>>
>>> generally the EtherCAT master should work with any Ethernet interface
>>> which is supported by the kernel if one uses the generic driver.
>>>
>>> Due to the fact that the generic driver uses parts of the regular
>>> network stack, don't expect good realtime behavior with an USB connected
>>> adapter.
>>>
>>> Regards Wilhelm
>>>
>>> Am 30.04.2019 um 01:40 schrieb Karl Zeilhofer:
>>>> Hi,
>>>>
>>>> has anyone experiences with running the IgH EtherCAT master via a
>>>> USB-Ethernet adapter?
>>>> I'm using one on one of my servers, which runs since years without
>>>> problems. It uses the r8152 Ethernet driver, which is not supported.
>>>>
>>>> For the first tests, I don't want to configure my main Ethernet port,
>>>> which is an e1000e, on my daily working machine.
>>>> As far as I understood from the documentation, that Ethernet port cannot
>>>> be used for the daily network traffic any more, right?
>>>>
>>>> If it would generally work over USB, I would buy a new adapter with one
>>>> of the supported chip sets. Any recommendations?
>>>>
>>> _______________________________________________
>>> etherlab-users mailing list
>>> etherlab-users at etherlab.org
>>> http://lists.etherlab.org/mailman/listinfo/etherlab-users
>> -- 
>> *Mechatronik* 	  	  	  	  	  	 
>> *Karl Zeilhofer* 	| 	Wengstraße 58 	| 	4643 Pettenbach 	| 	Austria
>> *www.zeilhofer.co.at <http://www.zeilhofer.co.at/>* 	|
>> karl at zeilhofer.co.at 	| 	+43 660 6591574 	| 	*UID:*ATU64031657
>>
>> ------------------------------------------------------------------------
>>
>>  
>>
>>
>>
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-- 
*Mechatronik* 	  	  	  	  	  	 
*Karl Zeilhofer* 	| 	Wengstraße 58 	| 	4643 Pettenbach 	| 	Austria
*www.zeilhofer.co.at <http://www.zeilhofer.co.at/>* 	|
karl at zeilhofer.co.at 	| 	+43 660 6591574 	| 	*UID:*ATU64031657

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