Profinet-for-Arduino
This is an open source Ethernet library for interfacing ARDUINO / ESP8266 / ESP32 natively with Siemens S7 PLCs.
Main Features
Full PLC memory access.
PDU independence, i.e. the data that you can transfer in a single call depends only on the Arduino memory availability.
Helper functions for data conversion (Big Endian --> Little endian)
Three memory models for footprint optimization.
Uses standard Arduino Ethernet library i.e. it can coexist with other clients/servers in the same sketch.
3 ms to read a PDU into the internal buffer, 24 ms for 1024 bytes into the external.
What do you need
An Arduino with an Ethernet Shield (with W5500) in which to load the examples
Alternatively, a NodeMCU board or Esp32 board
A Siemens PLC equipped with Ethernet port or Communication Processor.
Or if you don't have access to one then you can use PLC Sim for testing