Databases
StackOverflow2013
Postsdbo
POserial port threading hang
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POserial port threading hang
    primarykey
    data
    text
    <p>I got the code below from a website,and this way of serial port reading is my only option because DataReceived event often doesn't work.but this code has a problem,if I close the application while transfering the application hangs forever,but I can't see why?neither freezing nor aborting the thread work.actually aborting the thread causes the program to crash.</p> <pre><code>public class CommPort { SerialPort _serialPort; Thread _readThread; bool _keepReading; //begin Singleton pattern static readonly CommPort instance = new CommPort(); // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static CommPort() { } CommPort() { _serialPort = new SerialPort(); _readThread = null; _keepReading = false; } public static CommPort Instance { get { return instance; } } //end Singleton pattern //begin Observer pattern public delegate void EventHandler(string param); public EventHandler StatusChanged; public EventHandler DataReceived; private void StartReading() { if (!_keepReading) { _keepReading = true; _readThread = new Thread(new ThreadStart(ReadPort)); _readThread.Start(); } } private void StopReading() { if (_keepReading) { _keepReading = false; _serialPort.Close(); //_readThread.Join(); //block until exits _readThread.Abort(); //_readThread = null; } } private void ReadPort() { while (_keepReading) { if (_serialPort.IsOpen) { byte[] readBuffer = new byte[_serialPort.ReadBufferSize + 1]; try { // If there are bytes available on the serial port, // Read returns up to "count" bytes, but will not block (wait) // for the remaining bytes. If there are no bytes available // on the serial port, Read will block until at least one byte // is available on the port, up until the ReadTimeout milliseconds // have elapsed, at which time a TimeoutException will be thrown. int count = _serialPort.Read(readBuffer, 0, _serialPort.ReadBufferSize); String SerialIn = System.Text.Encoding.ASCII.GetString(readBuffer, 0, count); DataReceived(SerialIn); } catch (TimeoutException) { } } else { TimeSpan waitTime = new TimeSpan(0, 0, 0, 0, 50); Thread.Sleep(waitTime); } } } /// &lt;summary&gt; Open the serial port with current settings. &lt;/summary&gt; public void Open() { Close(); try { _serialPort.PortName = Properties.Settings.Default.COMPort; _serialPort.BaudRate = Properties.Settings.Default.BPS; _serialPort.Parity = Properties.Settings.Default.Parity; _serialPort.DataBits = Properties.Settings.Default.DataBit; _serialPort.StopBits = Properties.Settings.Default.StopBit; _serialPort.Handshake = Properties.Settings.Default.HandShake; // Set the read/write timeouts _serialPort.ReadTimeout = 50; _serialPort.WriteTimeout = 50; _serialPort.Open(); StartReading(); } catch (IOException) { StatusChanged(String.Format("{0} does not exist", Properties.Settings.Default.COMPort)); } catch (UnauthorizedAccessException) { StatusChanged(String.Format("{0} already in use", Properties.Settings.Default.COMPort)); } catch (Exception ex) { StatusChanged(String.Format("{0}", ex.ToString())); } // Update the status if (_serialPort.IsOpen) { string p = _serialPort.Parity.ToString().Substring(0, 1); //First char string h = _serialPort.Handshake.ToString(); if (_serialPort.Handshake == Handshake.None) h = "no handshake"; // more descriptive than "None" StatusChanged(String.Format("{0}: {1} bps, {2}{3}{4}, {5}", _serialPort.PortName, _serialPort.BaudRate, _serialPort.DataBits, p, (int)_serialPort.StopBits, h)); } else { StatusChanged(String.Format("{0} already in use", Properties.Settings.Default.COMPort)); } } /// &lt;summary&gt; Close the serial port. &lt;/summary&gt; public void Close() { StopReading(); StatusChanged("connection closed"); } public bool IsOpen { get { return _serialPort.IsOpen; } } } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USMPelletier
    1. USarmin
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POserial port threading hang
      1. This table or related slice is empty.
      1. VTUpMod
    1. COWhen you call StopReading in one thread, _keepReading is modified, but it's value is checked in the ReadPort while loop in a different thread (the _readThread). But _keepReading is not marked volatile, nor is its access locked or fenced. This is generally asking for trouble.
      singulars
      1. POserial port threading hang
      1. UShatchet
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload