fixup: example: DC sync on S=>O

[alexVinarskis]

There is a potential mistake in example, which had me banging head for quite some time with my motor controller: DC sync needed be performed during SAFEOP=>OPtransition, being first action. [source, search of SAFE]. At the same time, English source, claims it shall be performed during PREOP=>OP [source, search for PREOP], so there is clearly some misaligned. IMO its safe to assume English is wrong, as:

• There is simply no PREOP=>OP transition. Only PREOP=>SAFEOP and then SAFEOP=>OP.
• Original language of docs was German, translated to English, that could explain mistake
• Checking other sources online (eg, images below), its clear that it shall be SAFEOP=>OP.
• (May be subjective) In case of LS Servo drivers, original example simple does not work, device never goes OP. Fixing to order of German docs/image below everything works like a charm.

(not official source though):

I am not sure why it works in current example, I guess it depends per implementation, and some devices are less picky.

Hope this helps someone not to repeat my mistakes :) I can't find 100% solid and correct definition in EtherCAT standard when exactly this particular part shall be performed. Not sure this change shall be merged in right away, but wanted to raise this issue/inconsistency.

[bnjmnp]

Thank you for sharing. Often there are issues getting devices into OP state, and this could be worth looking into. I'll check that a bit further if there is some time.

[bnjmnp]

I finally tried your update on the example and merged your PR, sorry that it took me so long. Thank you again for your contribution.