Can somebody please explain dcconf and watchdog in XML?

Hi all,

I'm just starting out with EtherCAT, and I'm trying to configure my Servo drives. Looking at some example configs, I often see dcconf and/or watchdog tags with varying parameters.

Would somebody be so kind to explain in simple words what those lines do? Are they mandatory or just for optimization? Where do I find the correct parameters for my drives (Hiwin ED1 400W)?

A link to a good documentation of those tags would probably also be fine, I didn't find good info yet...

Cheers,
Matthias

dcConf is a setting some drives, typically servo and stepper motor drives, needs to synchronize the motion between them.
The choices are no synchronization (free run - often not accepted by drives), synchronization by precise time (DC - Distributed clocks) or synchronization by event (SM-synchronization).
What the drive accepts are in the ESI file for the drive and is set by a number in the assignActivate field. Check here for a lot of useful info on EtherCAT and a box for Synchronization www.ethercat.org/download/documents/Ethe..._Protocol_Poster.pdf
The sync0Cycle specifies the frequency of the DC clock cycle, or rather the period length. "*1" means 1 x applicationTime period, so often 1 ms. But different values can be given.
sync0Shift says exactly at which point inside this 1 ms the sync event takes place. 

watchdog is usually not needed, ethercat has a default 100 ms watchdog setting. Not sure what happens when the watchdog triggers.
It seems some drives needs this set specifically, such as the Stepperonline A6 servo drive.
The intervals are 40 nsec long, so the setting of intervals=2498 divider=1000 one can see ends up at 2498*40*1000 nsec = 99.92 msecs.
infosys.beckhoff.com/english.php?content...stem/1072459275.html

Thank you very much, Hakan!

I'll read the linked document, but your Explanation was perfectly understandable for a starter!

Cheers,
Matthias