4.1.2 EtherCAT State Machine
In each EtherCAT communication device a
state machine
is implemented. For each state
there is defined which communication service is active via EtherCAT. The state machine
of the slave station is controlled by the state machine of the EtherCAT master.
After power-on the EtherCAT members are in state
Init
. There is neither mailbox nor
process data communication possible. The EtherCAT master initializes the SyncManager
channels 0 and 1 for the mailbox communication.
The EtherCAT master initializes the SyncManager channels for process data (starting
with SyncManager channel 2), the FMMU channels and the PDO mapping respectively
the SyncManager PDO assignment. Further in this state the settings for process data
transfer and the module-specific parameters, which deviate from the default values are
transferred. During the transition from
Init
to
Pre-Op
the EtherCAT slave checks whether
the mailbox was correctly initialized. In the state
Pre-Op
mailbox communication and
Ethernet over EtherCAT (EoE) are possible but the process data communication is
blocked.
In
Safe-Op
the input data are cyclically updated but the outputs are de-activated. With the
transition from
Pre-Op
to
Safe-Op
the EtherCAT slave checks if the SyncManager chan-
nels for process data communication are correct. Before it acknowledges the state
change, the EtherCAT slave copies current input data to the corresponding DP RAM
areas of the EtherCAT slave controller. In the state
Safe-Op
mailbox and process data
communication is possible.
In the state
Op
the input data are cyclically updated and the EtherCAT master sends
output data to the EtherCAT slave. The EtherCAT slave copies the output data of the
master to its outputs and return input data to the EtherCAT master. In this state process
data and mailbox communication is possible.
In state
Boot
the firmware of an EtherCAT slave may be updated via the EtherCAT
master. This state may only be reached via Init. In the state
Boot
is mailbox communica-
tion via the protocol File-Access over EtherCAT (FoE) possible. Other mailbox and
process data communications are de-activated.
States
Init - 01h
Pre-Operational (Pre-Op) -
02h
Safe-Operational (Safe-
Op) - 04h
Operational (Op) - 08h
Bootstrap - option (Boot) -
03h
VIPA System SLIO
Deployment
Basics EtherCAT > EtherCAT State Machine
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