System.IO.IOException:连接到系统的设备无法运行C#.NET 4.0

Question

我已经构建了一个C#应用程序,它从串行端口读取和写入数据.连接到串行端口的设备是FTDI USB到串行转换器,它通过XBee无线模块与硬件通信.硬件测试电池模块的容量和稳态电压等.这些测试需要数天才能完成.

时不时串口似乎停止响应并抛出System.IO.IOException:连接到系统的设备无法正常运行错误.

这是堆栈跟踪:

at system.IO.Ports.InternalResources.WinIOError
at system.IO.Ports.SerialStream.EndWrite
at system.IO.Ports.SerialStream.Write
at system.IO.Ports.SerialPort.Write
at BatteryCharger.CommunicationClass.ApiTransmission

抛出此错误后,将抛出System.UnauthorizedAccessException: Access to the port is denied错误,并且每次软件尝试写入端口时都会发生此错误,并且它永远不会恢复,直到我停止调试并重新启动软件,仅在几天后发生同样的事情.

如何防止发生此错误,或者是否有办法从错误的catch语句中成功恢复这些错误？

我正在后台工作线程中连续读取串口并从另一个线程写入.

我也已经尝试过在本论坛上提出的所有遗留错误处理部分,但它们似乎没有任何区别.Windows XP Pro SP3 32位和Windows7 Pro 32位上出现错误.

这是CommunicationClass.cs - 串行传输代码.

    public static bool ApiTransmission(TXpacket transmission)
    {
        //clear all previous data that may have been in the buffer before doing a transmission
        Variables.dataParserPacket_buff.Clear();
        //TXpacket xbeetransmision = new TXpacket();
        byte[] packet = transmission.GeneratePacket();

        try
        {
            if (_serialPort.IsOpen)
            {
#if Console
                Log.write("TX-Packet: " + StringHandler.listToString(packet.ToList<byte>()));
#endif
                _serialPort.Write(packet, 0, packet.Length);
                Thread.Sleep(100);
            }
            else
            {
#if Console
                Log.write("serial port is closed");
#endif
                return false;
            }
        }
        catch (UnauthorizedAccessException ex)
        {
            MessageBox.Show(ex.ToString());
            Log.write("UnauthorizedAccessException");
        }
        catch (IOException ex)
        {
            MessageBox.Show(ex.ToString());
            Log.write("IOexception");
            //_serialPort.Close();
            //Thread.Sleep(100);
            //_serialPort.Open();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
#if Console
            Log.write(ex.ToString());
#endif
        }
        return true;

    }

这是我初始化串口的方法

    public CommunicationClass(string portName, int baudRate, Parity parity, int dataBits, StopBits stopBits)
    {
        _analysePacketBGW.DoWork += new DoWorkEventHandler(_analysePacketBGW_DoWork);
        _analysePacketBGW.WorkerReportsProgress = true;
        _analysePacketBGW.WorkerSupportsCancellation = true;

        _readBGW.DoWork += new DoWorkEventHandler(_readThread_DoWork);
        _readBGW.WorkerSupportsCancellation = true;
        _readBGW.WorkerReportsProgress = true;

        _parserStarterBGW.DoWork += new DoWorkEventHandler(_parserStarterThread_DoWork);
        _parserStarterBGW.WorkerSupportsCancellation = true;
        _parserStarterBGW.WorkerReportsProgress = true;
        if (_readBGW != null)
        {
            _readBGW.CancelAsync();
        }

        _serialPort = new SerialPort(portName, baudRate, parity, dataBits, stopBits);

        //SerialPortFixer.Execute(portName);
        //Thread.Sleep(1000);
        //using (_serialPort = new SerialPort(portName, baudRate, parity, dataBits, stopBits))
        //{
        //    //_serialPort.Open();
        //}

        _serialPort.ErrorReceived += new SerialErrorReceivedEventHandler(_serialPort_ErrorReceived);

        _dataqueuepp = new ManualResetEvent(false);

        _serialPort.Open();
        _readBGW.RunWorkerAsync();
        _parserStarterBGW.RunWorkerAsync();
        CommunicationClass.PacketReceived += new DataPacketReceived(CommunicationClass_PacketReceived);
    }

以及处理串口读取的后台工作者

    void _readThread_DoWork(object sender, DoWorkEventArgs e)
    {
#if Console
        Log.write("Read()");
#endif
        while (!_readBGW.CancellationPending)
        {
            try
            {
                int message = _serialPort.ReadByte();
                try
                {
                    Variables.dataQueue.Enqueue(message);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message + "     " + message.ToString());
                }
                _dataqueuepp.Set();
                //Console.Write(String.Format("{0:X2}", message) + " ");
            }
            catch (TimeoutException) { Log.write("read timeout"); }
            catch (IOException) { Log.write("read IOException"); }
            catch (ThreadAbortException) { Log.write("read thread aborted"); }
            catch (Exception ex) { MessageBox.Show(ex.ToString()); }
            finally { }
        }
    }

我现在将重写代码以从同一线程读取和写入串行端口,以查看是否有任何区别.

编辑

根据Jim的评论,我在IOException Catch语句中添加了以下内容:

        catch (IOException ex)
        {
            MessageBox.Show(ex.ToString());
            Log.write("IOexception");
            _readBGW.CancelAsync();
            Thread.Sleep(100);
            _serialPort.Close();
            Thread.Sleep(100);
            _serialPort.Open();
            Thread.Sleep(100);
            _readBGW.RunWorkerAsync();
            _serialPort.Write(packet, 0, packet.Length);
        }

希望通过停止后台工作者的_serialPort.Read,关闭端口,重新打开端口,再次运行后台工作程序并尝试再次写入相同的命令将足以成功从此错误中恢复.MessageBox仍然阻止代码,以便我可以看到错误发生的时间并可以监视它是如何恢复的.

我不喜欢修补这样的软件,但如果它有效,那么它的工作原理.

编辑2

添加上面的代码后,我的软件再次崩溃,但现在当我调用_serialPort.Close()时,它会抛出"UnauthorizedAccessException - 拒绝访问端口";

System.UnauthorizedAccessException was unhandled
Message=Access to the port is denied.
Source=System
StackTrace:
at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
at System.IO.Ports.InternalResources.WinIOError()
at System.IO.Ports.SerialStream.Dispose(Boolean disposing)
at System.IO.Stream.Close()
at System.IO.Ports.SerialPort.Dispose(Boolean disposing)
at System.IO.Ports.SerialPort.Close()
at BatteryCharger.CommunicationClass.ApiTransmission(TXpacket transmission) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\CommunicationClass.cs:line 436
at BatteryCharger.CommunicationClass.tx1(TXpacket packet, String callingMethod) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\CommunicationClass.cs:line 356
at BatteryCharger.XBee.setPin(String pinID, Byte status, XBee slave) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\XBee.cs:line 215
at BatteryCharger.XBee.setPins(Int32 pins, XBee slave) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\XBee.cs:line 177
at BatteryCharger.BatteryCharger.requestVoltage(Int32 block) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\BatteryCharger.cs:line 595
at BatteryCharger.BatteryCharger.requestVoltages() in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\BatteryCharger.cs:line 612
at BatteryCharger.Form1.RunCommandOn(List`1 battList, Int32 command, Double lowerLimit, Double upperLimit) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\Form1.cs:line 522
at BatteryCharger.Form1.chargeBlock(Int32 blockNr, Double lowerLimit, Double upperLimit) in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\Form1.cs:line 689
at BatteryCharger.Form1.<btnCheckCapacities_Click>b__13() in E:\Mijn Documenten\Research\Copy of BatteryCharger_V12\BatteryCharger\Form1.cs:line 619
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: 

这里发生了什么？

Answer 1

我大量使用 SerialPort 类通过 USB 适配器与 PLC 连续通信数月而没有任何中断。所以我不同意谁说 SerialPort .NET 类不起作用。尝试将类的创建插入到线程中，这里是使用BackgroundWorker 的代码示例。

    void ThreadEngine_DoWork(object sender, DoWorkEventArgs e)
    {
        // Do not access the form's BackgroundWorker reference directly.
        // Instead, use the reference provided by the sender parameter.
        BackgroundWorker objBackgroundWorker = sender as BackgroundWorker;

        try
        {
            mSerialPort = new SerialPort(GetPortName(mPortName), DefaultBaudRate, Parity.Even, 7, StopBits.Two);
            mSerialPort.Open();
            objBackgroundWorker.ReportProgress(0);

            while (objBackgroundWorker.CancellationPending == false)
            {
                if (IOScanner(objBackgroundWorker, false) == true)
                {
                    ScannerStationData();
                    IsReady = true;
                    IsError = false;
                }
                else
                {
                    IsReady = false;
                    IsError = true;
                }
                Thread.Sleep(1);
            }

            // Performs last scan before thread closing
            if (objBackgroundWorker.CancellationPending == true)
            {
                IOScanner(objBackgroundWorker, true);
            }

            mSerialPort.Close();
            mSerialPort = null;
            e.Result = null;
        }
        catch (Exception objErr)
        {
            string sMessage = string.Format("PlcService.ThreadEngine_DoWork Err={0}", objErr.Message);
            mLogSysService.AddItem(sMessage);
            IsError = true;
        }
    }

IOScanner 方法调用其他方法进行通信，如下所示。

    protected bool WriteDMWord(int iAddress, int[] aryValues)
    {
        bool bRetValue = true;
        try
        {
            mSerialPort.NewLine = "\r";
            mSerialPort.ReadTimeout = DefaultTimeout;
            string sTxData = HostLinkProtocol.BuildWriteDMWord(iAddress, aryValues);
            mSerialPort.WriteLine(sTxData);

            string sRxData = string.Empty;
            sRxData = mSerialPort.ReadLine();
            if (HostLinkProtocol.ParseWriteDMWord(sRxData) == true)
            {
                bRetValue = true;
            }
        }
        catch (Exception objErr)
        {
            Console.WriteLine("WriteDMWord [{0}]", objErr.Message);
            bRetValue = false;
        }
        return bRetValue;
    }