Hello,
The SHARKY 775 energy meter would need to be powered externally, either through a battery supply (e.g., 3.6 VDC A-cell with up to 10.5 years lifetime depending on configuration or a 3.6 VDC D-cell with up to 16 years lifetime) or mains supply (24 VAC), as the TRB143 is not designed to supply sufficient power for these devices.
In brief, the M-Bus interface on the TRB143 can support up to 250 energy meter slave devices when they are powered externally.
Feel free to reach out if you have further questions or need additional assistance.
Best regards,