How can I work with multiple slave ID

See more:

C#

Currently I am working on RFID reader with c#. I have to work multiple atmega2560, so every atmega have its own Slave ID, How Can I read multiple available Slave ID?

What I have tried:

lstBaudrate.SelectedIndex = 0;

        //3) Datatype:
        string[] dataTypes = { "Decimal" };

        foreach (string dataType in dataTypes)
        {
            lstDataType.Items.Add(dataType);
        }

        lstDataType.SelectedIndex = 0;
        string[] slaves = { "1", "2", "3", "4", "5" };
        //Textbox defaults:
        txtRegisterQty.Text = "3";
        txtSampleRate.Text = "1000";

        txtSlaveID.Text = "2";




        txtStartAddr.Text = "0";