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.
Test the echo back application through RaspberryPi and WIZ850io
This is a real time web interface to MQTT. Author describes the project step by step in details and that will make so much easier for any of you to follow.