Console App1

                using System;
                using System.Collections.Generic;
                using System.Linq;
                using System.Text;
                using System.Threading;
                using System.IO.Ports; 
                
                namespace ConsoleApp_SerialPort
                { 
                    class Program
                    {
                
                        #region CLASS functions  
                
                            public static SerialPort serialPort1;
                            public static Thread MyThread;
                
                
                        public static void ReadPortFeatures()
                        {
                            try
                            {
                                Console.WriteLine("Serial port INFO ==============================" );
                                Console.WriteLine("Serial port open    : " + serialPort1.IsOpen);
                                Console.WriteLine("Serial port Baud    : " + serialPort1.BaudRate);
                                Console.WriteLine("Serial port Name    : " + serialPort1.PortName);
                                Console.WriteLine("Serial port DBits   : " + serialPort1.DataBits);
                                Console.WriteLine("Serial port Parity  : " + serialPort1.Parity);
                                Console.WriteLine("Serial port StopBits: " + serialPort1.StopBits);
                                Console.WriteLine("===============================================");
                            }
                            catch
                            {
                
                                Console.WriteLine("PORT cannot be obtained.. ");
                            }

                        }    
                
                        public static void _serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
                        {
                            int dataLength = serialPort1.BytesToRead;   
                            byte[] data = new byte[dataLength];
                        
                            int nbrDataRead = serialPort1.Read(data, 0, dataLength);
                            if (nbrDataRead == 0)
                                return;
                
                            Console.WriteLine("{0}|{1}",dataLength, nbrDataRead);
                
                
                            // Send data to whom ever interested
                            // if (NewSerialDataRecieved != null)
                            //    NewSerialDataRecieved(this, new SerialDataEventArgs(data));
                        }
                
                        #endregion

                        #region MAIN()
                        static void Main(string[] args)
                        {
                            // get port names of available ports 
                            string[] ports = SerialPort.GetPortNames(); 
                            foreach (string item in ports)
                            {
                                Console.WriteLine("||| Ports available for reading on this PC  ... ");
                                Console.WriteLine("\n\t" + item);
                                Console.WriteLine("================================================");
                            }
                
                            // create the serial port object .. 
                            serialPort1 = new SerialPort("COM4", 115200, Parity.None, 8, StopBits.One);
                            if (serialPort1 != null)
                            {
                                Console.WriteLine("Serial Port has been created .. ");
                                ReadPortFeatures();
                            }
                
                            // Open port
                            if (serialPort1.IsOpen == false)
                            {
                                serialPort1.Open();
                                ReadPortFeatures();
                
                                string data_rx = serialPort1.ReadExisting();
                                Console.WriteLine(data_rx);

                                // port listener subscribed to event of Data received
                                // .. then call _serialPort_DataReceived()
                                serialPort1.DataReceived += new SerialDataReceivedEventHandler(_serialPort_DataReceived);
                                serialPort1.Close();
                        
                            }
                            else
                            {
                                Console.WriteLine("Port is bussy, cannot be opened now.. ");
                                return;
                            
                            }
                            Console.ReadLine();
                
                        }
                        #endregion MAIN 
                    }
                }
          

Multi channel reading

                using System;
                using System.Collections.Generic;
                using System.Linq;
                using System.Text;
                using System.Threading.Tasks;
                using System.IO.Ports;

                using System.Globalization;

                namespace ConsoleApp_Arduino
                {

                    public class Program
                    {
                        #region GLOBALS
                        public double ti = 0;          // time instance 
                        public double wi  = 0;          // value .. 
                        public static int k = 0;

                        #endregion 

                        // 
                        // M
                        // A
                        // I
                        // N
                        // =============================================================================
                        static void Main(string[] args)
                        {


                            //||||   SERIAL PORT STREAMING 
                            SerialPort my_com3 = new SerialPort();
                            my_com3.BaudRate = 115200;
                            my_com3.PortName = "COM3";           
                            my_com3.Open();

                    
                        Console.WriteLine("===============================================================================");

                            while (true)
                            {
                            
                                string data_rx = my_com3.ReadLine();
                                DataParsing(data_rx);
                                
                                
                                //Console.WriteLine("{0}", data_rx );
                            }



                        }//end of main 

                        #region DATA PARSING FUNCTION 
                        public static void DataParsing(string data_rx)
                        {
                            sbyte indexOf_startDataCharacter = (sbyte)data_rx.IndexOf("@");
                            sbyte indexOfA = (sbyte)data_rx.IndexOf("A");
                            sbyte indexOfB = (sbyte)data_rx.IndexOf("B");
                            sbyte indexOfC = (sbyte)data_rx.IndexOf("C");

                            if (indexOfA != -1 && indexOfB !=-1 && indexOf_startDataCharacter !=-1)
                            {
                                // @1509A1.5090B0.0618C

                                try
                                {
                                // strings 
                                    string s1 = data_rx.Substring(indexOf_startDataCharacter + 1, (indexOfA - indexOf_startDataCharacter)-1);
                                    string s2 = data_rx.Substring(indexOfA+1, (indexOfB - indexOfA)-1);
                                    string s3 = data_rx.Substring(indexOfB + 1, (indexOfC - indexOfB) - 1);
                                    k++;   

                                    Console.WriteLine("No: {0,5} | Li: {1,10} | ti: {2,10}| f(ti): {3,10} || t': {4,8}  | G(f(t)): {5,8} --|||", k, s1, s2, s3, 
                                        Convert.ToDecimal(s2, CultureInfo.InvariantCulture),
                                        Convert.ToDecimal(s3, CultureInfo.InvariantCulture));            
                                }
                                catch
                                {

                                    Console.WriteLine("DATA PACAKGE NOT as expected ... ");
                                }
                            
                            
                            }
                            #endregion
                        }
                    }
                }