serialport DataReceived事件

serialport DataReceived事件, 默認是收到一個byte就觸發事件.

            lock (thisLock)
            {
                int len = sp.BytesToRead;
                if (len > 0)
                {
                    Byte[] data = new Byte[len];
                    try
                    {
                        sp.Read(data, 0, len);
                    }
                    catch (System.Exception)
                    {

                    }
                    SerialPortEventArgs args = new SerialPortEventArgs();
                    args.receivedBytes = data;
                    Debug.WriteLine("**** port1_DataReceived=" + Encoding.Default.GetString(data));
                    if (comReceiveDataEvent != null)
                    {
                        comReceiveDataEvent.Invoke(this, args);
                    }
                }

            }

舉個例子,實際上返回的數據是*IDN?, 但每次觸發的次數都不一樣

**** port1_DataReceived=*
**** port1_DataReceived=IDN?

**** port1_DataReceived=*
**** port1_DataReceived=I
**** port1_DataReceived=DN?

**** port1_DataReceived=*
**** port1_DataReceived=I
**** port1_DataReceived=D
**** port1_DataReceived=N?

**** port1_DataReceived=*
**** port1_DataReceived=I
**** port1_DataReceived=D
**** port1_DataReceived=N
**** port1_DataReceived=?

**** port1_DataReceived=*
**** port1_DataReceived=IDN
**** port1_DataReceived=?

**** port1_DataReceived=*
**** port1_DataReceived=I
**** port1_DataReceived=DN?

 DataReceived 事件的處理,本質上是用線程來處理接收數據.

SerialPort類,請勿定義為局部變量, 因為局部變量在函數結束后就釋放了.而線程還沒結束,端口還沒釋放. 就會產生下面2種異常

System.ObjectDisposedException was unhandled
Message: An unhandled exception of type 'System.ObjectDisposedException' occurred in mscorlib.dll
Additional 

information: 已關閉 Safe handle

或者

System.UnauthorizedAccessException was unhandled
  HResult=-2147024891
  Message=對端口“COM5”的訪問被拒絕。