Question

I have a function under class Communication

    public int SerialCommunciation()
    {
        /*Function for opening a serial port with default settings*/
        InitialiseSerialPort();

        /*This section of code will try to write to the COM port*/   
        WriteDataToCOM();

        /*An event handler */                   
       _serialPort.DataReceived += new SerialDataReceivedEventHandler(_serialPort_DataReceived);

       return readData;
    }

Here

     int readData /*is a global variable*/

The _serialPortDataRecieved() updates the variable readData according to the data read from serial port

   /* Method that will be called when there is data waiting in the buffer*/
    private void _serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
    {

       string text = _serialPort.ReadExisting();
       int.TryParse(text, out readData);

    }

Now when i called this function from another class

   valueReadFromCom=Communication.SerialCommunication()

I needed to get the value read from serial port but instead i got 0.
When i tried debugging this code, i found out that control first goes to statement

   return readData;

in function SerialCommunication and only then control goes to function _serialPort_DataRecieved, function triggered by event. How can i make the whole process synchronous, that means readData should be returned from the function serialCommunication only after the function _serial_DataRecieved is performed.

Answer 1

Be adviced that the following is not the right way as serial port works async. On the otherhand it does the job anyway.

Just add a boolen property and check this property before returning from SerialCommunication function; set this property to true when data is received.

private bool dataReceived = false;   

public int SerialCommunciation()
{
    /*Function for opening a serial port with default settings*/
    InitialiseSerialPort();

    /*This section of code will try to write to the COM port*/
    WriteDataToCOM();

    /*An event handler */
    _serialPort.DataReceived += new SerialDataReceivedEventHandler(_serialPort_DataReceived);

    while (!dataReceived)
    {
        Thread.Sleep(1000);
    }
    return readData;
}

private void _serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
   string text = _serialPort.ReadExisting();
   int.TryParse(text, out readData);
   _serialPort_DataReceived = true;
}