Calculate charging max current received from RS485 Energy Meter

Introduction:
We are a small startup developing house charging stations. We already have some products, but for our entry level house charging station we would need dynamic load management.

Task:
The goal of the task is working DLM – Dynamic load management of house. One simple PCB needs to be built that reads current on all 3 phases and calculates possible charging current, depending on the max. current in the house el. network. PCB sends them via UART commands for charging current, depending on how much current the house has available.
For measuring the current we use ETI WM3M4 RS-485 3-phase energy meter. The energy meter measures all three phases and sends the current via RS-485.
For charging of EV we use Western Automation's controller – EVCC-01. The controller can control charging current via UART commands.

All available documentation can be provided on contact.

e.g.
Max. current in the house:
Imax = 25A
Iread = 10A
Because it is a 3 phase system, you should always take the biggest Iread.
Ipossible = Imax – Iread
Ipossible = I of UART command