Chapter 3 EtherCAT Communication States
ASDA A2-E
3-2
Revision April, 2015
Safe-Operational
Except SDO, for accessing Mailbox, the PDO (Process Data Object)
can only be applied for Process Data Input (TxPDO) at this stage.
Operational
The full function of SDO and PDO (TxPDO and RxPDO) are available
now.
3.1 State Transition Operation
The EtherCAT host will send different state transition command for requesting different
service.
State Change
Description
IP
Master will define the slave address and register SyncManager (0/1),
and it is possible to access mailbox.
Master will command the slave to switch to Safe-Operational state.
PS
SDO from the master will be employed for the settings of PDO
mapping.
Master will define FMMU and register SyncManager (2/3), and slaves
keep sending the PDO (TxPDO) packets to the master.
Master requests the Slave to switch to Operational state.
SO
Master starts to send PDO (RxPDO).
The distributed clock synchronization procedure takes place between
the master and slaves.
PI, SI, OI
All communication functions, including SDO and PDO cannot work.
Switch to Init State.
SP, OP
Disable PDO function.
Switch to Pre-Operational state
OS
Master stops sending Process Data Output (RxPDO).
Switch to Safe-Operational state
