BitBastelei
Some time ago, I acquired a transformer-based meter, which was supposed to provide significantly more data for power grid analysis than my previous S0 meter. The digital interface is called "Modbus" and is based on RS485. To familiarize myself with it, I grabbed a smaller, single-phase Modbus meter and looked at what was necessary to connect it to an ESP8266.
Library used: https://github.com/reaper7/SDM_Energy...