SFA-5000 • SFA-10000 EtherCAT
possible, e.g. larger mailbox size. In this state usually the FoE protocol is used
for firmware download.
The current state of the Slave is signalled through the green
RUN
LED, see on
page 26.
6.1.8 Slave configuration
The configuration of the Slave communication characteristics (Sync Manager
configuration, addresses, synchronization modes, PDO mapping, …) can be made
both using the XML file (EtherCat Slave Information - ESI) or loading data
directly from EEPROM (Slave Information Interface SII).
EEPROM content (SII):
6.1.9 Timing and Synchronization
The main feature of EtherCAT is its almost ideal representation of a real-time
system.
Hence the Master has to synchronize all the Slaves at the same time in order to
build a system where all nodes have the same reference time; this goal can be
achieved by using “distributed clocks”.
The Master downloads its clock into one of the Slaves (customarily the first
Slave) which becomes the reference clock for all the Slaves in the network; so it
has the task of synchronizing the other Slaves. The Master controller periodically
sends a special synchronization-telegram where the reference Slave writes its
own “current time”. This telegram is then sent to all the other Slaves that, in this
way, provide for a new re-synchronization of their own clock in order to avoid
possible drifts.
This synchronization of the reference time is very important in order to have a
snapshot of the system and accordingly to take simultaneous actions in high
sensitive applications such as the coordination in axis control operations.
Besides, the EtherCAT Slave Controller (ESC) is fitted with a capture/compare
unit that provides accurate synchronization signals (SYNC0 or interrupts): they
MAN SFA_5000_10000_EC E 1.0.odt
6 - EtherCAT® interface
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