Simultaneous Reading from Serial Port Problem

Hi Sudipto,

I have tried but still the same problem. Below i show you the whole code. The RFID reader & the sensor transmit data through the same single serial port.
When RFID reader reads RFID hanger & sensor detects an object(an L shape metal  passing by) simultaneously then the serial port cannot received the data from the sensor.

below is the setting at my property:

BaudRate = 9600

Databits = 8

DiscardNull = false

DtrEnable = False

GenerateMember = True

Handshake = none

Modifiers = private

Parity = None

ParityReplace = 63

PortName = Com1

ReadBuffersize = 768

Readtimeout = -1

Receivedbytesthreshold = 11

RtsEnable = false

Stopbits = One

WriteBuffersize = 768

writetimeout = -1

serialPort1.Open();

-----------------------------------------------------------------------

private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            StationDATA szCANData;
           
object objLock = new object();
lock (objLock)
{

            //String szData ="";
            int nBytesToRead = serialPort1.BytesToRead;
            byte[] szBuff = new byte[nBytesToRead];
            //string szCOM= serialPort1.ReadExisting();
            //szData += serialPort1.ReadExisting();
            //ProcessBuffer(szData);
            serialPort1.Read(szBuff, 0, nBytesToRead);
            
            szCANData.StationID = szBuff[0];
            szCANData.StationCMD = szBuff[1];
            szCANData.StationMSG0 = szBuff[2];
            szCANData.StationMSG1 = szBuff[3];
            szCANData.StationMSG2 = szBuff[4];
            szCANData.StationMSG3 = szBuff[5];
            szCANData.StationMSG4 = szBuff[6];
            szCANData.StationMSG5 = szBuff[7];
            szCANData.StationMSG6 = szBuff[8];
            szCANData.StationMSG7 = szBuff[9];
            szCANData.EOD = szBuff[10];
           
            // Convert the RFID HANGER NO DEC to ASCII

            string HangerID = "";

            
            //if (szCANData.StationCMD.ToString().Equals("10") || szCANData.StationCMD.ToString().Equals("75") )
            //{
                int decValue1 = szCANData.StationMSG0;
                int decValue2 = szCANData.StationMSG1;
                int decValue3 = szCANData.StationMSG2;
                int decValue4 = szCANData.StationMSG3;
                int decValue5 = szCANData.StationMSG4;
                int decValue6 = szCANData.StationMSG5;
                int decValue7 = szCANData.StationMSG6;
                int decValue8 = szCANData.StationMSG7;

                string hexValue1 = decValue1.ToString("X");
                string hexValue2 = decValue2.ToString("X");
                string hexValue3 = decValue3.ToString("X");
                string hexValue4 = decValue4.ToString("X");
                string hexValue5 = decValue5.ToString("X");
                string hexValue6 = decValue6.ToString("X");
                string hexValue7 = decValue7.ToString("X");
                string hexValue8 = decValue8.ToString("X");

                StringBuilder sb1 = new StringBuilder();
                StringBuilder sb2 = new StringBuilder();
                StringBuilder sb3 = new StringBuilder();
                StringBuilder sb4 = new StringBuilder();
                StringBuilder sb5 = new StringBuilder();
                StringBuilder sb6 = new StringBuilder();
                StringBuilder sb7 = new StringBuilder();
                StringBuilder sb8 = new StringBuilder();

                for (int i = 0; i <= hexValue1.Length - 2; i += 2)
                {
                    sb1.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue1.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));                    
                }
            
                for (int i = 0; i <= hexValue2.Length - 2; i += 2)
                {
                    sb2.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue2.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue3.Length - 2; i += 2)
                {
                    sb3.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue3.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue4.Length - 2; i += 2)
                {
                    sb4.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue4.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue5.Length - 2; i += 2)
                {
                    sb5.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue5.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue6.Length - 2; i += 2)
                {
                    sb6.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue6.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue7.Length - 2; i += 2)
                {
                    sb7.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue7.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }

                for (int i = 0; i <= hexValue8.Length - 2; i += 2)
                {
                    sb8.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexValue8.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
                }
            
            
                HangerID = sb1.ToString() + sb2.ToString() + sb3.ToString() + sb4.ToString() + sb5.ToString() + sb6.ToString() + sb7.ToString() + sb8.ToString();
            //}             

                        
            SetTextBox(szCANData.StationCMD.ToString());            
            
            RecvCANData(szCANData.StationCMD, szCANData.StationID.ToString(), HangerID);                                                
                                                               
            
            serialPort1.DiscardInBuffer();
            //serialPort1.Write(StructureToByteArray(szLogon), 0, Marshal.SizeOf(szLogon));

}                     

        }

Please advice. Thanks

I think this will solve your problem.......
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
StationDATA szCANData;
//String szData ="";
object objLock = new object();
lock (objLock)
{
int nBytesToRead = serialPort1.BytesToRead;
byte[] szBuff = new byte[nBytesToRead];
//string szCOM= serialPort1.ReadExisting();
//szData += serialPort1.ReadExisting();
//ProcessBuffer(szData);
serialPort1.Read(szBuff, 0, nBytesToRead);
szCANData.StationID = szBuff[0];
szCANData.StationCMD = szBuff[1];
szCANData.StationMSG0 = szBuff[2];
szCANData.StationMSG1 = szBuff[3];
szCANData.StationMSG2 = szBuff[4];
szCANData.StationMSG3 = szBuff[5];
szCANData.StationMSG4 = szBuff[6];
szCANData.StationMSG5 = szBuff[7];
szCANData.StationMSG6 = szBuff[8];
szCANData.StationMSG7 = szBuff[9];
szCANData.EOD = szBuff[10];
}
}