3 The EtherCAT finite state machine
XN-312-GW-EC gateway 07/20 MN050010-EN
Eaton.com
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3 The EtherCAT finite state machine
The are various states and state transitions that are defined in the EtherCAT
protocol. XN-312-GW-EC gateways implement these EtherCAT states using
the system bus for communication with the XN300 slice modules.
Figure 12:
EtherCAT states and state transitions
State
Description
Notes
INIT
Device booting.
The EtherCAT master will search for nodes on
the system bus and generate an object list.
The SDO/PDO nodes configuration is being
generated and stored as a CoE object
dictionary. The Mailbox SyncMaster is being
configured.
The module status LED on
the station's nodes will flash
green.
INIT -> PRE-OPERATIONAL
• Mailbox SyncManager (SM) will be
configured.
• Distributed Clock (DC) will be configured.
PRE-OPERATIONAL
The device has been started and has checked
in on the EtherCAT bus
The PDO transfer is being initialized but has
not yet started. Input and output data is not
being transmitted yet.
PRE-OPERATIONAL -> SAFE
OPERATIONAL
• The module list will be read by the
EtherCAT master
• PDO SMs will be configured
• FMMUs will be configured
• PDO mapping will be written by the
master
• Configuration of XN300 slice modules via
CoE.
• The system bus is starting with the PDOs
for the inputs
