Synchronization - Beckhoff EL6731 Documentation

EtherCAT communication EL6731-00x0
stored DP slave configuration. If the PREOP state is quit, the current DP configuration in objects 0xF800,
0x8yy0, 0x8yy1 and 0x8yy2 can be read. The cycle time of the EtherCAT master (0x1C32:02) must still be
transmitted before the EL6731 is switched to SAFEOP.
PDO Mapping / PDO Assign
In addition, the EtherCAT master can also read the PDO Mapping and PDO Assign in the PREOP state in
order to determine the lengths of the EtherCAT process data.
Creating the Backup Parameter Storage
The Backup Parameter Storage can be created as follows:
1. Download object 0x10F2 (in PREOP without having sent StartUp SDOs beforehand): in this case the data
received will be saved as Backup Parameter Storage in the flash memory
Deleting the Backup Parameter Storage
In order to load a new Backup Parameter Storage or to simply delete the existing one, the value
0x64616F6C has to be written to entry 0x1011:01.
6.1.2

Synchronization

In the EL 6731, the DP cycle is synchronized with the EtherCAT cycle. Synchronization takes place by
default via the Sync Manager 2 event or, if there is no EtherCAT output process data, via the Sync Manager
3 event. Alternatively, the EL6731 can also be operated in the Distributed Clocks mode, in which case
synchronization takes place via the SNYC0 or SYNC1 events.
SM-synchronous
The illustration below shows the sequence of the DP cycle if no Distributed Clocks are used.
Fig. 131: Sequence of the DP cycle without distributed clocks
When receiving the EtherCAT process data telegram, the SM2 event (SM3 if no EtherCAT output data are
configured, i.e. only DP slaves without DP outputs) is generated by the EtherCAT slave controller, thus
starting the DP cycle. A data exchange telegram with the output process data received over EtherCAT is
thereby sent for each configured DP Slave (that is in the data exchange state). The sequence corresponds
to the sequence of the configuration, i.e. it starts with the DP slave configured in the objects 0x800z. Once all
138 Version: 2.8 EL6731