Hello, it will depend on the way you want to organize polling process.
For simultaneous connection you can reach up to 63 devices via instanced tcp client fb’s. This number is limited by TCP/TLS port handling opportunity of plc.
But if you will organize sequential read/write access to meters, one by one, the number of devices is almost unlimited. You just change configuration of single tcp-client fb, do the staff and disconnect.
BR.