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EtherCAT Communication
EtherCAT State Machine (ESM)
EPOS4 Communication Guide
CCMC | 2019-11 | rel8759
4-43
Table 4-16
EtherCAT communication – ESM conditions
Table 4-17
EtherCAT communication – ESM transitions
Condition
Description
Power ON
• EPOS4 is ON
• EPOS4 autonomously initializes and switches to state “Init”
Init
• Master will synchronize the EtherCAT field bus
• Asynchronous communication between Master and Slave (Mailbox) will be
established. At this time, no direct communication (Master to/from Slave) will yet
take place.
• When all devices have been connected to the field bus and have successfully
passed configuration, state will be changed to “Pre-Operational”
Pre-Operational
• Asynchronous communication between Master and Slave (Mailbox) will be active.
• Master will setup cyclic communication via PDOs and necessary parameterization
via acyclic communication.
• Upon successful completion, the Master will change to state “Safe-
• Operational”.
Safe-Operational
• Used to establish a safe operation condition of all devices connected to the
EtherCAT field bus. Thereby, the Slave sends actual values to the Master while
ignoring new setpoint values of the Master and using save default values instead.
• Upon successful completion, the Master will change to state “Operational”
Operational
• Acyclic as well as cyclic communication is active
• Master and Slave exchange setpoint and actual values
• EPOS4 be enabled and operated via the CoE protocol
Bootstrap
• Only FoE is possible (Mailbox)
• Firmware download via FoE
Transition
Status
IP
Start of acyclic communication (Mailbox)
PI
Stop of acyclic communication (Mailbox)
PS
Start of cyclic communication (Process Data)
Slave sends actual values to Master
Slave ignores setpoint values by the Master and uses default values
SP
Stop of cyclic communication (Process Data)
Slave ceases to send actual values to the Master
SO
Slave evaluates actual setpoint values of the Master
OS
Slave ignores setpoint values from Master and uses internal default values
OP
Stop of cyclic communication (Process Data)
Slave ceases to send actual values to the Master
Master ceases to send actual values to the Slave
SI
Stop of cyclic communication (Process Data)
Stop of acyclic communication (Mailbox)
Slave ceases to send actual values to the Master
Master ceases to send actual values to the Slave
OI
Stop of cyclic communication (Process Data)
Stop of acyclic communication (Mailbox)
Slave ceases to send actual values to the Master
Master ceases to send actual values to the Slave
IB
Start Bootstrap Mode
Firmware download via FoE (Mailbox)
BI
Reset device after successful firmware download