[etherlab-dev] Bus rescan while realtime operation

Erwin Burgstaller ethercat.berknapp at spamgourmet.com
Wed Jan 20 17:33:08 CET 2010


Although this list seams pretty dead, first post this year and my last
questions never been answered or even recognized, I'm giving another

In the news for version 1.4 there's written: 

"Slave scanning is now done any time the bus topology changes, even
during realtime operation."

So why did this came in? I think the previous behavior has been pretty
cool, the newer one might be dangerous instead.

If I have several EtherCAT slaves of the same type in line, for example
digital outputs, and one of them is missing after the rescan, e.g. slave
3, the digital outputs on slave 4 will be accessed instead, which may
cause big troubles on things we handle.

How may my realtime module recognize the start of the scan and when it's

Any other ideas to handle such a situation other than with a shutdown
of the whole operation?


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