c# - serialPort_DataReceived 事件的问题

Question

我在通信类下有一个函数

    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;
    }

这里

     int readData /*is a global variable*/

_serialPortDataRecieved()根据从串口读取的数据更新变量readData

   /* 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);

    }

现在当我从另一个类调用这个函数时

   valueReadFromCom=Communication.SerialCommunication()

我需要从串行端口读取值，但我得到的是 0。当我尝试调试这段代码时，我发现控件首先转到语句

   return readData;

在函数 SerialCommunication 中，然后控制转到函数 _serialPort_DataRecieved，该函数由事件触发。我怎样才能使整个过程同步，这意味着 readData 应该仅在函数 _serial_DataRecieved 执行后从函数 serialCommunication 返回。

Answer 1

请注意，以下不是正确的方式，因为串口工作异步。另一方面，它无论如何都能完成工作。

只需添加一个 boolen 属性并在从 SerialCommunication 函数返回之前检查此属性；收到数据时将此属性设置为 true。

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;
}