The most important work to archive real-time EtherCAT Master on Raspberry Pi is the real-time capable driver for Network controller, W5500 chip in this case. W5500 is controller via SPI interface, writing driver for W5500 is mostly about working with SPI on Raspberry pi.
Roma Angela J.
The Arduino+Ethernet shield are set up as a Web-client that receives commands from the Web-server. Here, a command represents status of LEDs - on or off; potentially, it can be some other desirable manipulation of I/O ports