Reputation: 819
serialport responding to EventHandler, but not ReadExisting or ReadLine?
i have a program that's reading from serial port in c#. i need to quickly write to a port, read from it, then close it. i cannot leave it open. i understand that serial ports read and write slowly, I've tried to set the ReadTimeout and WriteTimeout properties high, and added a thread.Sleep to try to drag the read and write times out for the devices. here's a little bit of code:
my method to write to port:
private void CheckPorts(string testMessage)
{
foreach (string s in SerialPort.GetPortNames())
{
portNumber = Int32.Parse(s.Remove(0, 3));
testSerial = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
if (testSerial.IsOpen)
{
testSerial.Close();
}
testSerial.ReadTimeout = 2000;
testSerial.WriteTimeout = 1000;
testSerial.Open();
if (testSerial.IsOpen)
{
string received;
testSerial.DiscardInBuffer();
try
{
//testSerial.DataReceived += new SerialDataReceivedEventHandler(testSerialPort_DataReceived);
testSerial.Write(testMessage);
System.Threading.Thread.Sleep(2000);
received = testSerial.ReadExisting(); //EITHER I USE THIS OR EVENT HANDLER, NOT BOTH
}
catch (TimeoutException e)
{
testSerial.Close();
continue;
}
if (received.Length > 0)
{
MessageReceived(received);
}
testSerial.Close();
}
}
}
private void testSerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
string received = testSerial.ReadExisting();
int y = received.IndexOf("\r");
while (y == -1)
{
received = received + testSerial.ReadExisting();
y = received.IndexOf("\r");
}
if (testSerial.IsOpen)
{
testSerial.Close();
}
}
i'm wondering, if i absolutely have to use datahandler, how do i keep the serial port open long enough to read from it, but close the serialport before the next port needs to be opened?
see, the first method gets called a few times, and it iterates through a foreach loop, trying a message on a few ports, then trying to read a response. so, at some point i have to close the ports, or else the next time it goes through it, it doesn't work properly because the port is still open
HERE'S MY UPDATED CODE (still not working):
private void CheckPorts(string testMessage, int baudRate)
{
foreach (string s in SerialPort.GetPortNames())
{
var interval = 3000; // ms
var timer = new System.Timers.Timer(interval);
timer.Elapsed += (o, e) =>
{
timer.Enabled = false;
if (testSerial.IsOpen)
testSerial.Close(); // may not be necessary with Dispose?
testSerial.Dispose();
timer.Dispose();
};
portNumber = Int32.Parse(s.Remove(0, 3));
testSerial = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
testSerial.ReadTimeout = 2000;
testSerial.WriteTimeout = 2000;
if (testSerial.IsOpen)
{
testSerial.Close();
}
testSerial.Open();
timer.Enabled = true;
if (testSerial.IsOpen)
{
string received;
//testSerial.DiscardInBuffer();
//autoEvent = new AutoResetEvent(false);
try
{
// testSerial.DataReceived += new SerialDataReceivedEventHandler(testSerialPort_DataReceived);
// autoEvent.Reset();
lblPortNum.Content = s;
lblPortNum.Refresh();
testSerial.Write(testMessage);
//System.Threading.Thread.Sleep(2000);
//testSerial.NewLine = "\r\n";
byte[] rBuff = new byte[2];
int rCnt = testSerial.Read(rBuff, 0, 2);
System.Text.Encoding enc = System.Text.Encoding.ASCII;
received = enc.GetString(rBuff);
//received = testSerial.ReadLine();
}
catch (TimeoutException e)
{
testSerial.Close();
continue;
}
if (received.Length > 0)
{
MessageReceived(received, Int16.Parse(s.Remove(0, 3)));
}
/*
if (autoEvent.WaitOne(2000))
{
// the port responded
// testSerial.Close();
autoEvent.Dispose();
lblPortNum.Content = "HEY I RESPONDED";
}
else
{
testSerial.Close();
autoEvent.Dispose();
continue;
// port did not respond within 2 seconds
}*/
//testSerial.Close();
}
}
}
UPDATED AGAIN (still not working properly)
private void CheckPorts(string testMessage, int baudRate)
{
foreach (string s in SerialPort.GetPortNames())
{
portNumber = Int32.Parse(s.Remove(0, 3));
// MUST BE LOCAL
var serialOneOfMany = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
serialOneOfMany.ReadTimeout = 2000;
serialOneOfMany.WriteTimeout = 2000;
if (serialOneOfMany.IsOpen)
{
serialOneOfMany.Close();
}
// timer must be defined _after_ serialOneOfMany
var interval = 3000; // ms
var timer = new System.Timers.Timer(interval);
timer.Elapsed += (o, e) =>
{
timer.Enabled = false;
if (serialOneOfMany.IsOpen)
serialOneOfMany.Close(); // may not be necessary with Dispose?
serialOneOfMany.Dispose();
timer.Dispose();
};
if (serialOneOfMany.IsOpen)
{
string received;
try
{
lblPortNum.Content = s;
lblPortNum.Refresh();
serialOneOfMany.Write(testMessage);
byte[] rBuff = new byte[2];
int rCnt = serialOneOfMany.Read(rBuff, 0, 2);
System.Text.Encoding enc = System.Text.Encoding.ASCII;
received = enc.GetString(rBuff);
}
catch (TimeoutException e)
{
serialOneOfMany.Close();
continue;
}
if (received.Length > 0)
{
CheckIfTheMessageMatches(received, Int16.Parse(s.Remove(0, 3)));
}
}
}
}
so with this update, it just blows through the code, i can step through the code line by line, but it doesn't stop for 3 seconds at all. if i run it without any debugging breaks, it just goes through it i a fraction of a second
UPDATE 10-25-11
private void CheckPorts(string testMessage, int baudRate)
{
foreach (string s in SerialPort.GetPortNames())
{
string received = "";
testSerial = new SerialPort(s,baudRate, Parity.None, 8, StopBits.One);
lblStatus.Content = "Scanning...";
lblStatus.Refresh();
if (testSerial.IsOpen)
{
testSerial.Close();
}
else
{
testSerial.Open();
}
if (testSerial.IsOpen)
{
try
{
testSerial.NewLine = "\r";
lblPortNum.Content = s;
lblPortNum.Refresh();
testSerial.WriteTimeout= 500;
testSerial.ReadTimeout = 1000;
testSerial.WriteLine(testMessage);
System.Threading.Thread.Sleep(500);
/*THIS DOESN'T WORK
byte[] buffer = new byte[testSerial.BytesToRead];
int rCnt = testSerial.Read(buffer, 0, buffer.Length);
received = enc.GetString(buffer);*/
//received = Convert.ToString(testSerial.BaseStream.Read(buffer, 0, (int)buffer.Length));
received = testSerial.ReadLine();
int y = received.IndexOf("\r");
while (y == -1)
{
received = received + testSerial.ReadExisting();
y = received.Length;
}
if (lblInfo.Dispatcher.Thread == Thread.CurrentThread)
{
CheckIfTheMessageMatches(received, s);
received = received + lblInfo.Content;
lblInfo.Content = received;
}
else
{
lblInfo.Dispatcher.Invoke(DispatcherPriority.Normal, new ThreadCheck(threadCheck), received);
}
if (testSerial.IsOpen)
{
testSerial.Close();
}
/*I USE THIS WITH THE sPort.Read() METHOD
while (rCnt > 0)
{
if (lblInfo.Dispatcher.Thread == Thread.CurrentThread)
{
CheckIfTheMessageMatches(received, s);
rCnt = 0;
received = received + lblInfo.Content;
lblInfo.Content = received;
}
else
{
lblInfo.Dispatcher.Invoke(DispatcherPriority.Normal, new ThreadCheck(threadCheck), received);
}
}
*/
if (testSerial.IsOpen)
{
testSerial.Close();
}
}
catch (TimeoutException e)
{
testSerial.Close();
continue;
}
received = null;
}
}
lblStatus.Content = "Finished Scanning.";
lblPortNum.Content = "";
}
UPDATED CODE here's some new code, still not working, dataeventhandler not even called once. i know it's getting messages because i have another program that works with the serial devices
private void CheckPorts(string testMessage, int baudRate)
{
foreach (string s in SerialPort.GetPortNames())
{
var serialOneOfMany = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
serialOneOfMany.ReadTimeout = 700;
serialOneOfMany.WriteTimeout = 100;
var interval = 500; // ms
var timer = new System.Timers.Timer(interval);
timer.Elapsed += (o, e) =>
{
timer.Enabled = false;
if (serialOneOfMany.IsOpen)
serialOneOfMany.Close(); // may not be necessary with Dispose?
serialOneOfMany.Dispose();
timer.Dispose();
};
timer.Enabled = true;
lblStatus.Content = "Scanning...";
lblStatus.Refresh();
if (serialOneOfMany.IsOpen)
{
serialOneOfMany.Close();
}
else
{
serialOneOfMany.Open();
}
if (serialOneOfMany.IsOpen)
{
string received;
try
{
lblPortNum.Content = s;
lblPortNum.Refresh();
serialOneOfMany.WriteLine(testMessage);
System.Threading.Thread.Sleep(400);
serialOneOfMany.DataReceived += new SerialDataReceivedEventHandler(testSerialPort_DataReceived);
}
catch (TimeoutException e)
{
serialOneOfMany.Close();
continue;
}
}
}
lblStatus.Content = "Finished Scanning.";
lblPortNum.Content = "";
}
private void testSerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort receivingSerial = sender as SerialPort;
string received = receivingSerial.ReadExisting();
int y = received.IndexOf("\r");
while (y == -1)
{
received = received + receivingSerial.ReadExisting();
y = received.IndexOf("\r");
}
if (lblInfo.Dispatcher.Thread == Thread.CurrentThread)
{
string name = receivingSerial.PortName;
received = received + lblInfo.Content;
lblInfo.Content = received;
CheckIfTheMessageMatches(received, name);
}
else
{
lblInfo.Dispatcher.Invoke(DispatcherPriority.Normal, new ThreadCheck(threadCheck), received);
}
if (receivingSerial.IsOpen)
{
receivingSerial.Close();
}
}
Upvotes: 5
Views: 9024
Answers (7)
Reputation: 10244
You may be best with BackgroundWorker. Eg:
BackgroundWorker worker=new BackgroundWorker();
worker.DoWork += (s, dwe) =>
{
// do your serial IO here
worker.RunWorkerCompleted += (s, rwe) =>
{
// check for rwe.Error and respond
};
worker.RunWorkerAsync();
Upvotes: 0
Reputation: 819
You can't use Thread.Sleep. It blocks the read from the device. You need to spawn a new thread.
Upvotes: 0
Reputation: 1
open the port in public form1 just after/below the InitializeComponent(); myport.open and close the after data is received. worked!
Upvotes: -1
Reputation: 4838
Please have a look at this (I also used in an answer to a serial port related question asked by darthwillard). All the ports are opened one after another, the DataReceived events are bound (all you need to do there is to test the incoming message), but no waiting is required. The timer event handler can close all the ports or keep the one you want to use etc. I hope it helps!
private List<SerialPort> openPorts = new List<SerialPort>();
private void button3_Click(object sender, EventArgs e)
{
int baudRate = 9600;
string testMessage = "test";
txtPortName.Text = "Testing all serial ports";
foreach (string s in SerialPort.GetPortNames())
{
SerialPort newPort = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
if (!newPort.IsOpen)
{
try
{
newPort.Open();
}
catch { }
}
if (newPort.IsOpen)
{
openPorts.Add(newPort);
newPort.DataReceived += new SerialDataReceivedEventHandler(serialOneOfMany_DataReceived);
newPort.Write(testMessage);
}
else
{
newPort.Dispose();
}
}
txtPortName.Text = "Waiting for response";
tmrPortTest.Enabled = true;
}
private void serialOneOfMany_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
txtPortName.Text = ((SerialPort)sender).PortName;
}
private void tmrPortTest_Tick(object sender, EventArgs e)
{
tmrPortTest.Enabled = false;
foreach (SerialPort port in openPorts)
{
if (port.PortName != txtPortName.Text)
{
port.Close();
port.Dispose();
}
}
}
Upvotes: 1
Reputation: 1459
Try setting your event handler before you write to the port, and then see if it doesn't catch your break point.
Upvotes: 0
Reputation: 50215
You should be able to do these simultaneously (assuming that's ok). You would then close them as the DataReceived event is raised (extraneous code removed). Just don't close the port in CheckPorts.
private void testSerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort localSerialPort = sender as SerialPort;
... // use localSerialPort instead of global/class variable
if (localSerialPort.IsOpen)
{
localSerialPort.Close();
}
}
EDIT: Responding to comment.
You can always add a timer on the fly. If you put this in the foreach loop, you'll get a timer for every serial port that will dispose its given serial port after 3 seconds. It's important here that the timer is declared within the foreach loop.
var interval = 3000; // ms
var timer = new System.Timers.Timer(interval);
timer.Elapsed += (o,e) =>
{
timer.Enabled = false;
if (testSerial.IsOpen)
testSerial.Close(); // may not be necessary with Dispose?
testSerial.Dispose();
timer.Dispose();
}
timer.Enabled = true;
EDIT: Code updated so I'll update
Scope is very important with the code I provided. You should get rid of the non-local testSerial or use an entirely different name here.
portNumber = Int32.Parse(s.Remove(0, 3));
// MUST BE LOCAL
var serialOneOfMany = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
serialOneOfMany.ReadTimeout = 2000;
serialOneOfMany.WriteTimeout = 2000;
if (serialOneOfMany.IsOpen)
{
serialOneOfMany.Close();
}
// timer must be defined _after_ serialOneOfMany
var interval = 3000; // ms
var timer = new System.Timers.Timer(interval);
timer.Elapsed += (o, e) =>
{
timer.Enabled = false;
if (serialOneOfMany.IsOpen)
serialOneOfMany.Close(); // may not be necessary with Dispose?
serialOneOfMany.Dispose();
timer.Dispose();
};
Upvotes: 4
Reputation: 21855
Check this info from Microsoft:
This method returns the contents of the stream and internal buffer of the SerialPort object as a string. This method does not use a time-out. Note that this method can leave trailing lead bytes in the internal buffer, which makes the BytesToRead value greater than zero.
Why don't use the usual Read method SerialPort.Read (Byte[], Int32, Int32)
Upvotes: 1
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