Omron GX-AD0471, User Manual, Page: 70 / 394

5 EtherCAT Communications
5 - 4 GX-series EtherCAT Slave Unit User’s Manual
5-3 Communications State Transitions
The EtherCAT State Machine (ESM) indicates the state transition model of EtherCAT Slave Unit
communications control. It is controlled by EtherCAT Master Unit.
The following figure shows the communications state transitions from power ON.
State
SDO
communi
cations
PDO
transmiss
ion
PDO
reception
Contents
Initialization (Init)
Not
possible. Not
possible. Not
possible. Communications are being initialized.
Communications are not possible.
Pre-Operational
(Pre-Op)
Possible
Not
possible. Not
possible.
SDO (message) communications are
possible in this state.
This state is entered after initialization has
been completed. It is used to initialize
network settings.
Safe-Operational
(Safe-Op)
Possible Possible
Not
possible.
In this state, PDO transmissions are possible
in addition to SDO (message)
communications.
PDO sendings can be used to send
information such as status from the Slave
Unit.
Operational (Op) Possible Possible Possible
Normal communication state
PDO communications can be used to control
the I/O data.
Initialization
Pre-Operational
Safe-Operational
Operational
Power ON