[etherlab-users] EtherCAT cycle time on slave

Jun Yuan j.yuan at rtleaders.com
Wed Dec 7 15:32:54 CET 2011

OK, just figured it out myself. Indeed the slave using Sync Unit Cycle to
detect the bus cycle. And I forgot to add the following line to active DC:

    // configure SYNC signals for this slave
    ecrt_slave_config_dc(sc, 0x0300, 2000000, 0, 0, 0);

I should have read the dc example more carefully

On Wed, Dec 7, 2011 at 1:42 PM, Jun Yuan <j.yuan at rtleaders.com> wrote:

> Hi,
> 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
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