[etherlab-users] Duplicated values bug, when measuring external frequency generator signal, with beckhoff EL3064 &EL3062 slaves and etherlab

[Jun Yuan]

 Hello Lazaros,

It seems the master and the slave didn't work synchronized, did you
activate the DC Sync? Which slave carries the reference clock? What does
the value of the register 0x92c on EL3064/EL3062 look like?

Regards,
Jun


On Thu, Mar 13, 2014 at 5:33 PM, Lazaros Penteridis <
lazapenteridis at gmail.com> wrote:

> Hello,
>
> I have etherlab(the latest versions of all the components) installed,
> under a 3.4.69-rt85 linux kernel, in 3 different computers, which I
> connected with beckhoff EL3064 or EL3062 slave, via ethernet using the
> beckhoff EK1100 coupler.
>
> Using this set up, I measure, as input to the EL3064 or EL3062 slaves, a
> sine wave signal with 40ms period, produced from a frequency generator. I
> performed this experiment using different sampling frequencies and I notice
> in the measured signals that some sample values are duplicated(two adjacent
> samples have the same value). The frequency that this duplicating error
> occurs varies relative to the sampling frequency that I choose for the
> slaves(the errors occur more rarely the higher the sampling period goes
> until the point that, with 1300us sampling period, I get a mean error
> occurrence frequency of approximately 1 per day.
>
> Bellow you will find attached an image showing these duplications, for a
> signal that was measured with sampling period of 1000us. For the logging of
> the measured data both test manager scope and dls from igh where used, with
> no difference in the results of course.
>
> The frequency of the duplications is not related to which of the 3
> computers is being used, under the same sampling frequency, so I'm assuming
> it's not related to the computational power and the performance of my
> real-time systems.
>
> Could you suggest what the reason for these duplications might be(beckhoff
> hardware problem, software bug) and if there is something I could do to get
> rid of it?
>
> Thank you in advance,
> Lazaros
>
>
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>


-- 
Jun Yuan
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Robotics Technology Leaders GmbH
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