Software
Fig. 23:
Automatic DC synchronisation in redundancy case
Important notes about automatic DC synchronisation:
•
Primary and secondary side can’t be exchanged, it’s always the primary side
that adapts its time to the secondary side’s time
•
The primary side has to be the DC reference slave of its EtherCAT segment
•
The EtherCAT master must accept the time from the primary side as it is:
Usually each slave’s time is adapted with the DC offset register (0x0920) by the
master – automatic synchronisation is no longer possible then.
If the master is not configurable accordingly the application must handle the
automatic synchronisation and e.g. enable it only after the master has written
the DC offset registers (which usually implies restarting the slave’s DC sync
units as well, etc.)
•
The secondary side’s time should not be changed uncontrolled – the time
stamps and their “invalid” bit in the process data (object 0x10F4, see 6.3.1.6)
should be used to react on the loss of synchronisation
•
Typically an accuracy of about 100 ns can be reached
Page 36 of 74
Manual • Doc. No.: E.3022.21 / Rev. 1.9
ECX-EC
Slave
n
...
Slave6
Slave5
Master
Slave1
Slave2
Slave3
Slave4
Redundancy:
Primary
Redund.
Slave
n
...
Slave6
Slave5
Master
Slave1
Slave2
Slave3
Slave4
ECX-EC
Primary
Redund.
Auto sync
enabled
Normal operation:
(Pri.)
(Sec.)
(Pri.)
(Sec.)
