[etherlab-users] delays in the etherlab I/O blocks?

Florian Pose fp at igh-essen.com
Mon Oct 19 17:13:00 CEST 2009

On Mon, Oct 19, 2009 at 03:19:36PM +0200, Julian Stoev /  Юлиан Стоев wrote:
> On Mon, Oct 19, 2009 at 11:36 AM, Florian Pose <fp at igh-essen.com> wrote:
> > I think the phase delay originates from the way, the EtherCAT bus is
> > operated. After setting your outputs, the outputs are sent to the
> > slaves, while the current slave inputs are queried at the same time(!).
> > That means, that the response to your outputs is received at minimum one
> > cycle later, that's why it depends on the IO cycle time.
> I am not sure I understand exactly. Do you mean that querying and
> actual reading of the slaves should be regarded as two different
> samples. The command is given to query. The values become available on
> the next time sample?

It just means, that if you send a command to a slave at cycle n, the
response to this command is visible in the process data in cycle n + 2,
because reading and writing is done together at the beginning of each

Best regards,
Florian Pose


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