Fronius PV Inverter with grid meter

I have a fronius symo inverter. If I connect to openems via modbus over TCP, it reads correctly the production value from the inverter. However, I have a (Fronius) smart meter which measures the grid connection, and it is connected to the inverter via modbus over some wires (so not on the home network).

How can I get openems to read that grid power value out? it is supposed to be Modbus device id 240 on the inverter.
Is there a ready made component in openems which I can use? (I did not find a generic modbus power meter)
Do I have to implement a new modbus meter class? Do I have to work on the Fronius PV inverter class such that it also acts as a grid power meter?