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Appendix| EtherCAT
optoNCDT 2300
A 7.2.5 EtherCAT State Machine
The EtherCAT® state machine is implemented in each EtherCAT®. Directly after switching on the optoNCDT2300, the state machine
is in the „Initialization“ state. In this state, the master has access to the DLL information register of the slave hardware. The mailbox is
not yet initialized, i.e. communication with the application (sensor software) is not yet possible. During the transition to the pre-oper-
ational state, the Sync Manager channels are configured for the mailbox communication. In the „Pre-Operational“ state, communica-
tion via the mailbox is possible, and it can access the object directory and its objects. In this state, no process data communication
occurs. During the transition to the „Safe-Operational“ state, the process-data mapping, the Sync Manager channel of the process
inputs and the corresponding FMMU are configured by the master. Mailbox communication continues to be possible in the „Safe-
Operational“ state. The process data communication runs for the inputs. The outputs are in the „safe“ state. In the „Operational“ state,
process data communication runs for the inputs as well as the outputs.
Initialization
Pre-Operational
Operational
Safe-Operational
Fig. 63 EtherCAT State Machine
A 7.2.6 CANopen over EtherCAT
The application level communication protocol in EtherCAT is based on the communication profile CANopen DS 301 and is designated
either as “CANopen over EtherCAT” or CoE. The protocol specifies the object directory in the sensor, as well as the communication
objects for the exchange of process data and acyclic messages. The sensor uses the following message types:
- Process Data Object (PDO). The PDO is used for the cyclic I/O communication, therefore for process data.
- Service Data Object (SDO). The SDO is used for acyclic data transmission.
The object directory is described in the chapter CoE Object Directory.
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