The EtherCAT configuration file ENI contains one or more Cyclic entries for reading new input data values and output data values (process data update). These entries contain one or more frames, so-called cyclic frames, which are to be sent cyclically by the EtherCAT master. Within the cyclic frames are one or more EtherCAT datagrams that contain logical read/write commands for accessing the process data values.
In the simplest case, there is only a single cyclic entry with one or more cyclic frames.
For more complex scenarios it is possible to configure the system using multiple cyclic entries with one or more cyclic frames for each cyclic entry.