Thanks ChirpyChips aka @Beormund.

I used your implementation with ESPHome to interface with a Schneider Phase Inverter. I wrote a tutorial on Hackster.io.
https://www.hackster.io/nicolaudosbrinquedos/m5stack-stamp-plc-as-real-plc-3ec3ed
Thank you very much for your work!

@djairguilherme Nice! At some point I really do need to utilise ESPHome's RS-485 support to expose the M5StamPLC's PWR-485 interface as a Modbus slave. It's on my TODO list.