RS485 is not a protocol, it is just an electrical standard.
What protocols is the energy meter capable of supporting (e.g. Modbus).

What programming tool for the PLC are you using? TIA / PCS7 etc

If the energy meter is Modbus the documentation will have a register map. You will need that to determine the addresses to request.

 Hello,

tahamuhsin

Hi, 

Yes, you are right sorry :).I am using the Modbus protocol. But it is not known PLC. I am using an IoT gateway that is developed myself. And pymodbus library. There is no problem, with different energy analyzers. The problem is just for iskra mc350. 

I am trying to get Total Real Power from 30140 registers. There is no problem with physical connections. 

  you can see, your answer can be best as first init question to be clear what help you need. As smiffy already sugested, documentation and also Modbus general knowledge. I can give you one tip, from your register address is clear that Input register is used (FC 4) and register address is 139. Due this info you can built proper modbus request. As your system is your own made, no support logically but you need to know that, correct?