Network Operation; Ethercat Communication Architecture; Ethercat State Machine - WEG CFW11 User Manual

6

NETWORK OPERATION

Following it shows operating characteristics of the CFW11 frequency inverter using EtherCAT interface.
6.1

ETHERCAT COMMUNICATION ARCHITECTURE

The following figure presents the CFW11 frequency inverter architecture for network data exchange.
The application layer protocol used by the EtherCAT is based on CANopen DS301 protocol, called CANopen over
EtherCAT (CoE). Among the main structures used in communication, it can be highlighted:
Object Dictionary
All the data exchange is based on the object dictionary, which is a list of available data for communication configuration
and operation of the equipment.
PDOs
PDOs are used to define and transmit process data (cyclic data) communicated between master and slave for control
and monitoring equipment.
SDO
The equipment has an SDO server that enables the exchange of acyclic data, for setting up communication and
parameterization. Data exchanged via SDO utilize the mailbox structure for sending commands and receiving the
response by the network master.
6.2

ETHERCAT STATE MACHINE

Every EtherCAT slave has a state machine responsible for defining the activities to be performed between master and
slave. After power on, the slave goes to the startup state, and other state transitions typically occur as requested by
network master.
Figure 6.1: EtherCAT communication architecture
Network Operation
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