Lenze EtherCAT Controller-based Automation - Manual (Page 23)

Lenze · Controller-based Automation · EtherCAT® Communication Manual · DMS 6.4 EN · 04/2014 · TD17
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4 The Lenze automation system with EtherCAT
4.1 Brief description of EtherCAT
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4.1.2.3 Working counter
Each EtherCAT datagram contains a working counter (WKC) which is incremented by each slave
after the data have been processed successfully.
The working counter (WKC) can be used as a diagnostics option to check the processing of the
EtherCAT telegrams by the slaves.
In each cycle, the Lenze Controller compares the expected value of the working counter with the
value read back via the fieldbus. If the read-back value is smaller than the expected value, not all
addressed slaves have been reached. The controller detects this and reports an error.
 Messages: WKC Error / Not all slaves "Operational" / SyncManager Watchdog ( 177)
Example
• 10 slaves read/write process data in the "Operational" state
Expected value of the WKC: 10
• A cable break between the 8th and 9th slave causes the master to be unable to access slave 9
and slave 10:
• Value of the restored WKC: 8
• An error response is initiated in the Lenze Controller.
• The EtherCAT bus changes to the state "Pre-Operational".