The ET112 (for single phase max. 100A) and the ET340 (for three phase max. 65A) Energy Meters are typically used in an Energy Storage System.
The EM24 is for 3 phase monitoring only.
There is a EM24 meter model for RS485 connection and one that connects over Ethernet. All ET models connect via RS485.
To measure the power and energy of the whole application at the distribution box. Or to measure the output of a PV Inverter, to display the data on the Color Control GX and the VRM Portal.