ABB FECA-01 EtherCAT, User Manual

Page: 91 / 148

Communication protocol 91
EtherCAT state machine
The adapter module includes the EtherCAT state machine
mandatory for all EtherCAT devices. The state machine is defined
in the following figure. The bootstrap state is not supported.
The adapter module enters the Initialization (INIT) state directly
after start-up. After this, the adapter module can be switched to the
Pre-operational (PREOP) state. In the PREOP state the EtherCAT
mailbox communication is allowed and CoE objects can be
accessed by SDOs.
After the master has configured the slave, it can switch the adapter
module to the Safe-operational (SAFEOP) state. In this state input
I/O data (PDOs) is sent from the adapter module to the EtherCAT
master, but there is no output I/O data from the master to the
adapter module.
To communicate output I/O data the master must switch the
adapter module to the Operational state.
Initialization
Operational
Pre-operational
Safe-operational