Develop Reference

Appending strings received within a subscriber method?

In the code below, the strings received within myReceivedLines appear when connecting with my serial port (when connecttodevice is true). However they disapear when I launch another command (when homeall is true).
I added the field called myReceivedLines within the class so that I could use the method String.Add() to all the feedback received and commands sent (having like a console within the program).
Why does the feedback dispear when a command is sent and how can I make sure all the strings stay in the variable myReceivedLines? Is the string going to myReceivedLine disapearing because they happen within a subscriber method? How do I solve that?
NB: GH_DataAccess.SetDataList(Int32, IEnumerable) is a method from the Kernel a software called Grasshopper to assign values to an output (it has to be used within the GH_Component.SolveInstance() method which is also from this Kernel), I am using this to visualise myReceivedLines.
code:
public class SendToPrintComponent : GH_Component
{
//Fields
List<string> myReceivedLines = new List<string>();
SerialPort port;
//subscriber method for the port.DataReceived Event
private void DataReceivedHandler(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
while (sp.BytesToRead > 0)
{
try
{
myReceivedLines.Add(sp.ReadLine());
}
catch (TimeoutException)
{
break;
}
}
}
protected override void SolveInstance(IGH_DataAccess DA)
{
//Opening the port
if (port == null)
{
string selectedportname = default(string);
DA.GetData(1, ref selectedportname);
int selectedbaudrate = default(int);
DA.GetData(2, ref selectedbaudrate);
//Assigning an object to the field within the SolveInstance method()
port = new SerialPort(selectedportname, selectedbaudrate, Parity.None, 8, StopBits.One);
//Enables the data terminal ready (dtr) signal during serial communication (handshaking)
port.DtrEnable = true;
port.WriteTimeout = 500;
port.ReadTimeout = 500;
}
//Event Handling Method
bool connecttodevice = default(bool);
DA.GetData(3, ref connecttodevice);
**if (connecttodevice == true)**
{
if (!port.IsOpen)
{
port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
DA.SetDataList(0, myReceivedLines);
port.Open();
}
}
else
if (port.IsOpen)
{
port.DataReceived -= new SerialDataReceivedEventHandler(DataReceivedHandler);
port.Close();
}
if (port.IsOpen)
{
DA.SetData(1, "Port Open");
}
//If the port is open do all the rest
if (port.IsOpen)
{
bool homeall = default(bool);
DA.GetData(5, ref homeall);
//Home all sends all the axis to the origin
**if (homeall == true)**
{
port.Write("G28" + "\n");
myReceivedLines.Add("G28" + "\n");
DA.SetDataList(2, myReceivedLines);
}
}
else
{
DA.SetData(1, "Port Closed");
}
}
}

If you are trying to append to a string, I would reccomend a StringBuilder object.
Or the less cleaner resolution, use the += operator,
string s = "abcd";
s+="efgh";
Console.WriteLine(s); //s prints abcdefgh

First of all your variables (myReceivedLines and port) are not static. I'm not sure if you want them to be static because I can't see how your using SendToPrintComponent class.
And could you explain DA.SetDataList(0, myReceivedLines); or better yet include the code because the problem could be there...

NullReferenceException: Object reference not set to an instance of an object on a SerialPort.ReadLine() method

When running the code below, I get the following NullReferenceException. What am I missing?
System.NullReferenceException was unhandled
Message=Object reference not set to an instance of an object.
Source=Silkworm
StackTrace:
at UnhandledExceptionLogger.UnhandledDomainException(Object sender, UnhandledExceptionEventArgs args)
Code:
//Fields
List<string> myReceivedLines;
//subscriber method for the port.DataReceived Event
private void DataReceivedHandler(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
while (sp.BytesToRead > 0)
{
try
{
myReceivedLines.Add(sp.ReadLine());
}
catch (TimeoutException)
{
break;
}
}
}
protected override void SolveInstance(IGH_DataAccess DA)
{
string selectedportname = default(string);
DA.GetData(1, ref selectedportname);
int selectedbaudrate = default(int);
DA.GetData(2, ref selectedbaudrate);
bool connecttodevice = default(bool);
DA.GetData(3, ref connecttodevice);
SerialPort port = new SerialPort(selectedportname, selectedbaudrate, Parity.None, 8, StopBits.One); //Create the serial port
port.DtrEnable = true; //enables the Data Terminal Ready (DTR) signal during serial communication (Handshaking)
port.Open(); //Open the port
if ((port.IsOpen) && (connecttodevice == true))
{
port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
DA.SetDataList(0, myReceivedLines);
}

myReceivedLines = new List<string>()

myReceivedLines is declared, but never assigned a value, so it remains null. You probably want to initialise it, like:
List<string> myReceivedLines = new List<string>();
Then, you can proceed to use it.

Why is received data from the Serial Port Null?

The code below builds with no errors, the connection to the device seems to work too although I do not get any feedback from the device.
on V.S., I have placed a break point at the linemyReceivedLines = sp.ReadExisting(); and the variable myReceivedLines comes back null.
On another similar program connecting to the same device, couple lines of feedback appear (see below), why is this variable null in my case?
Lines that appear on other program:
Connecting...
start
Printer is now online.
echo:Marlin: 1.0.0 RC2
echo: Last Updated: 2012-05-22-1 | Author: eMAKER
...etc...
Code:
//Fields
string myReceivedLines;
//subscriber method for the port.DataReceived Event
private void DataReceivedHandler(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
myReceivedLines = sp.ReadExisting();
}
protected override void SolveInstance(IGH_DataAccess DA)
{
List<string> gcode = new List<string>();
DA.GetDataList(0, gcode);
string selectedportname = default(string);
DA.GetData(1, ref selectedportname);
int selectedbaudrate = default(int);
DA.GetData(2, ref selectedbaudrate);
bool connecttodevice=default(bool);
DA.GetData(3, ref connecttodevice);
bool sendtoprint= default(bool);
DA.GetData(4, ref sendtoprint);
if (!DA.GetDataList(0, gcode)) return;
if (!DA.GetData(1, ref selectedportname)) return;
if (!DA.GetData(2, ref selectedbaudrate)) return;
if (!DA.GetData(3, ref connecttodevice)) return;
if (!DA.GetData(4, ref sendtoprint)) return;
SerialPort port = new SerialPort(selectedportname, selectedbaudrate, Parity.None, 8, StopBits.One); //Create the serial port
port.DtrEnable = true; //enables the Data Terminal Ready (DTR) signal during serial communication (Handshaking)
port.Open(); //Open the port
port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
if (gcode == null)
{
AddRuntimeMessage(GH_RuntimeMessageLevel.Warning, "Specify a valid GCode");
return;
}
if (connecttodevice == true)
{
DA.SetDataList(0, myReceivedLines);
}
else
{
port.Close();
}
if (sendtoprint == true)
{
foreach (String s in gcode)
{
port.WriteLine(s);
}
}
}

if (connecttodevice == true)
{
DA.SetDataList(0, myReceivedLines);
}
SerialPort.ReadExisting() cannot return null, at worst you'll get an empty string. The simple explanation is that you are using myReceivedLines before any data was received. Which is very likely in this case, you are using it right after you open the port. The odds that DataReceived will fire before you use myReceivedLines are vanishing small. The code is pretty inscrutable, you'll need to substantially revise it. Just keep in mind that the serial port will receive data at an entirely unpredictable moment in time. You'll need to have your DataReceived event handler push progress.

serialport and dispatchertimer, how to make my thread pause when com port is open?

i have a serial port that will iterate through the ports with this method:
foreach (string s in SerialPort.GetPortNames())
{
var serialOneOfMany = new SerialPort(s, baudRate, Parity.None, 8, StopBits.One);
if (serialOneOfMany.IsOpen)
{
serialOneOfMany.Close();
}
else
{
try
{
serialOneOfMany.Open();
}
catch
{
var openSerial = new System.Timers.Timer(3100);
openSerial.Elapsed += (o, e) =>
{
serialOneOfMany.Open();
openSerial.Enabled = false;
openSerial.Dispose();
};
openSerial.Enabled = true;
}
}
if (serialOneOfMany.IsOpen)
{
string received;
try
{
lblPortNum.Content = s;
lblPortNum.Refresh();
serialOneOfMany.Write(testMessage);
serialOneOfMany.DataReceived += new SerialDataReceivedEventHandler(testSerialPort_DataReceived);
}
catch (TimeoutException e)
{
serialOneOfMany.Close();
continue;
}
}
}
so, i want to open the port, send it a message, listen for the response, then close it. as everyone knows, every comport found in GetPortNames isn't a valid serial port. so, what i've been doing is setting a timer with a dispatcher timer:
DispatcherTimer time = new DispatcherTimer();
time.Interval = TimeSpan.FromMilliseconds(3000);
time.Tick += new EventHandler(someEventHandler);
time.Start();
here's the other method handled here:
private void someEventHandler(Object sender, EventArgs args)
{
SerialPort serial = (SerialPort)sender;
if (serial.IsOpen)
serial.Close();
serial.Dispose();
//if you want this event handler executed for just once
DispatcherTimer thisTimer = (DispatcherTimer)sender;
thisTimer.Stop();
}
so, it'll open the com port, if it doesn't get a response within 3 seconds, it will close the port. the problem i'm having is that the foreach loop will just barrel through the code and open the comport several times, i'll get a message saying The COM Port is open already and can't be used. so basically it's not pausing in openSerial.
i want it to open a new serial port, and if it's not accessible, wait 3100 milliseconds and try again. how do i do that?
UPDATED CODE:
private void button1_Click(object sender, RoutedEventArgs e)
{
CheckPorts();
}
private void checkPorts()
{
SendMessage("messageToDevice1", 19200);
SendMessage("Message2", 9600);
}
private void SendMessage(string testMessage, int baudRate)
{
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.Write(testMessage);
newPort.DataReceived += new SerialDataReceivedEventHandler(serialOneOfMany_DataReceived);
}
else
{
newPort.Dispose();
}
}
txtPortName.Text = "Waiting for response";
tmrPortTest.Enabled = true;
}
my new problem is that it just blows through the com ports, i need it to stop for each one, take a second to listen, then close it. it just blows through the foreach loop.
now, the reason why i don't just open up the port and keep it open through all the messages is that my devices have different baud rates, and i can't adjust them to all match. so, i need to open the ports, then send messages, listen, if they don't respond to the first round of messages, then open them up at the new baudrate and send a new batch of messages. but the foreachloop doens't pause for me to listen.

I think this more or less agrees with rare's answer. The port where you receive a response (you would probably want to check the response as well) will remain open and all the others should close.
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.Write(testMessage);
newPort.DataReceived += new SerialDataReceivedEventHandler(serialOneOfMany_DataReceived);
}
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();
}
}
}

Here's how I would do this --
First, try to open all the serial ports. The ones that actually do open are put in a list.
Assign all serial ports in the list to the same DataReceived event handler. The event handler is where you will save the port name (it's in the args) and kill the timer if you rx'd the response
Send your testMessage out all the open ports
Set just one timer for 3.1 seconds
Close the ports once the timer fires or the event handler rx's the response.

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();
}
}

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();
};

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)

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();
}
}
}

Try setting your event handler before you write to the port, and then see if it doesn't catch your break point.

You can't use Thread.Sleep. It blocks the read from the device. You need to spawn a new thread.

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();

open the port in public form1
just after/below the InitializeComponent(); myport.open
and close the after data is received.
worked!