Energy monitor device "eastron SDM320M" modbus rtu on bus 485

There are several topics on integration of Eastron meters, for example

Try the search functionality of the forum, search for SDM or Eastron. You need to look into the address manual of your device and modify the addresses accordingly.

I have 3x single phase meters and they work fine with OH3. BTW you mention HA3 so if it is home assistant, you are at a wrong place.