Ethercat State Machine - YASKAWA UAK series User Manual

8 Operation
8.2

EtherCAT State Machine

The EtherCAT State Machine (ESM) is responsible for the coordination of master and slave applications at
start up and during operation. State changes are typically initiated by requests of the master.
The states of the EtherCAT State Machine are as follows.
Power ON
INIT
INIT => PREOP
PREOP
PREOP => SAFEOP
SAFEOP
SAFEOP => OP
OP
8-4
(PI)
PRE-OPERATIONAL
(PREOP)
(OI)
(OP)
State
• No mailbox communication is possible.
• No process data communication is possible.
• Master configures DL Address and SyncManager channels for Mailbox communication.
• Master initializes DC clock synchronization.
• Master requests 'Pre-Operational' state.
• Master sets AL Control register.
• Slave checks whether the mailbox was initialized correctly.
• Mailbox communication is possible.
• No process data communication is possible.
• Master configures SyncManager channels and FMMU channels for process data.
• Master configures PDO mapping and the sync manager PDO assignment parameters via
SDO.
• Master requests 'Safe-Operational' state.
• Slave checks whether the sync manager channels for process data communication and, if
required, the distributed clocks settings are correct.
• Mailbox communication is possible.
• Process Data communication is possible, but only Inputs are evaluated – Outputs remain in
'Safe' state.
• Master sends valid Outputs.
• Master requests 'Operational' state.
• Mailbox communication is possible.
• Process data communication is possible.
INIT
(IP)
(SI)
(PS) (SP)
SAFE-OPERATIONAL
(SAFEOP)
(SO) (OS)
OPERATIONAL
(OP)
Description