[etherlab-users] EtherCAT cycle time on slave

Jun Yuan j.yuan at rtleaders.com
Wed Dec 7 13:42:42 CET 2011


there is a slave CoE device, which works with the TwinCAT. And now I am
trying to bring it work with the EtherLab-Master.

When the EtherLab-Master goes into OP, the slave will also be in OP.
There's no error. The working counter is OK. The PDO communication should
be fine.
However, I found out actually, the CoE device does neither take any command
from the RxPdos, nor update its state in the TxPdos. Those data in the
input domain remain the same for that moment the slave turned into OP, and
don't change any more. But I can see those object have actually changed via
SDO access.

Then I thought, there must be some configuration problems on the CoE
device, since it didn't act/react with the PDOs on the EtherCAT bus. So I
called the service & support of its manufacturer. They send an expert, and
he found out that their device complains that the cycle time is 0 ms when
turning into OP, and that I should set the EtherCAT cycle time.

AFAIK, the EtherCAT cycle time in the Etherlab-Master is only in that while
loop with the clock_nanosleep(). How should I tell the slave about this
cycle time? Since there is no CoE object on that device for the cycle time
configuration, I kindly asked him, HOW?

He said, he don't know about the EtherLab, but for the TwinCAT, he only
needs to set it in the "Freerun Cycle (ms)" under the Adapter option. Then
he showed me on my PC. Well, yes, the slave works. And I was speechless.
There must be some magic that I don't know yet.

Now I've found out that it must have something to do with the "DC for
synchronization", since if I deactivate it in the slave configuration in
TwinCAT. The slave device will no longer know about the EtherCAT cycle time
of the TwinCAT. I think, the device learns about the cycle time through DC.
But what should I do on my etherlab-master?

Can anybody help me out?

Best Wishes,

Jun Yuan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.etherlab.org/pipermail/etherlab-users/attachments/20111207/6b3c662d/attachment-0002.htm>

More information about the Etherlab-users mailing list