Case study of a knitting plant with many machines from different makers on one factory WiFi. One ESP32 PLC per knitting machine reads the machine contacts through coupling relays, the speed and the shaft turns on interrupt inputs, and a three-phase power meter. It publishes the state, the alarms and the energy over MQTT, and a concentrator in each production area keeps the data until the server confirms it.

The PDF covers the challenge, the three stages (state, energy, delivery), the system architecture with the signal table and the hardware used. Interactive version: knitting machine energy monitoring case study online.