i've run into this pretty tricky problem recently and i hoped somebody could help me.
i have a program that uses trackbars as to display sound volume and it's controlled with an Arduino via serial.
When i try to modify the value (programmaticaly) of the trackar (moving the slider) in any method, it works perfectly with the following code :
trackbar1.Value = ...;
However, when i put this in my serial data handler, it doesn't works :/
I declare the serial data handler this way :
//declaring arduinoCom
public SerialPort arduinoCOM;
//In form1
arduinoCOM.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
my handler looks like this :
public void DataReceivedHandler(
object sender,
SerialDataReceivedEventArgs e)
{
trackBar2.Value = 50;
}
The serial communication works flawlessly, and the handler does it's job no problem.
I've tried for 2 days now and i was able to identify that the only difference between the working trackbar and the not-working one is where the "trackbar1.value" is located. So i've remove the rest of the (i hope) unessecary code for clarity reasons.
So my Question is why does the Trackbar slider doesn't move when i try to modify it's value outside of the "standards method"
additional informations : I've tried runnning the program and then pausing it with visual stuio and the trackbar.Value has been changed successfully, the only thing that isn't working is the graphics side.
I've tested with multiple trackbars, and tried using
trackbar1.Refresh();
it didn't work
Picture of the value of trackbar 1 and 2 as well as picture of all 5 :
Values of trackbars
trackbars not moving
The DataReceived event for SerialPort is raised on a secundary thread (not the UI thread) from which you cannot change UI elements.
Using 'Invoke', you can make the change in the UI thread
Instead of
public void DataReceivedHandler(
object sender,
SerialDataReceivedEventArgs e)
{
trackBar2.Value = 50;
}
use:
public void DataReceivedHandler(
object sender,
SerialDataReceivedEventArgs e)
{
if (trackbBar2.IsHandlecreated) trackBar2.Invoke(new Action(() => trackbar.Value = 50));
}
I found the problem, when i was declaring my serial communication i was using `
Form1 form1 = new Mixer.Form1();
initialiseSerialEventHandler(arduinoCOM);
and instead i should only use
initialiseSerialEventHandler(arduinoCOM);
Related
I downloaded the Vlc.DotNet project from Github and have been adding more functionalities to its Sample Forms application. Everything goes fine, except on thing: I noticed that every time I start the application and play an audio, the audio sounds like its volume is 100% (or something around that) - even after I set it to a lower value.
I tried setting the volume before playing the audio, but it didn't work.
If I debug the code, I see that the volume is always set to -1.
For instance, if I execute the following lines of code, after setting the volume to 40, when I debug it, the volume is still -1:
myVlcControl.Play(new FileInfo(FileName));
myVlcControl.Audio.Volume = 40;
Change the order of the lines above also doesn't work.
The funny thing is, when the audio is already playing and I change the volume,it is successfully changed to the select value on the NumericUpDown. The code below is the event where this happens:
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
myVlcControl.Audio.Volume = (int)numericUpDown1.Value;
}
I've been trying to solve this problem for two days now. Unfortunately, my coding skills are not even close the people behind this project. I have already posted this problem on their Issues page on Github, but since there are questions since November without replies, I decided to try the StackOverflow. Hopefully someone here uses Vlc.DotNet and have a solution for my problem.
That being said:
Does anyone have the same problem?
Does anyone know how to solve it?
Any suggestions?
Thanks!
[EDIT on Jan 8, 2016, 11:50 AM GMT-2]
The user higankanshi on Github answered me the following:
I have found the problem.
You should use LibVlc 2.2.0(or later).
Vlc.DotNet is using LibVlc 2.1.5
Then, I executed some tests and came to the following conclusions:
You're right. Using the LibVlc 2.2.0 I'm able to set the Volume before playing.
Unfortunately, for some reason, setting the volume before playing the audio only works on the first time the application is opened. After stopping the audio, changing the volume, and playing it again, the volume doesn't change anymore - only changes while playing.
Here are the steps with results:
Execute the application;
Change the volume at run time before playing an audio file;
Play the audio file;
RESULT: the audio plays at the specified volume, successfully! =)
Press Stop;
Change the volume again;
Press Play again (at this point, the implementation inside the play method should get the new volume information);
RESULT: the audio plays again at the same volume it played before. Setting the volume doesn't work anymore.
I'm doing my tests on the Vlc.DotNet.Forms.Samples - CLR 4 - .Net 4.5 project. The changes I've made to the project were:
Added a NumericUpDown control, so that I could change the volume at run time;
Associated the ValueChanged event to the NumericUpDown control, so that every time it changes the value, the new value is passed to the VlcControl;
Created a Play() function that always gets the last volume value before playing the audio;
My code is below:
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
myVlcControl.Audio.Volume = (int)numericUpDown1.Value;
}
private void Play()
{
myVlcControl.Audio.Volume = (int)numericUpDown1.Value;
myVlcControl.Play(new FileInfo(FileName));
}
private void OnButtonPlayClicked(object sender, EventArgs e)
{
Play();
}
private void OnButtonStopClicked(object sender, EventArgs e)
{
myVlcControl.Stop();
}
private void OnButtonPauseClicked(object sender, EventArgs e)
{
myVlcControl.Pause();
}
Any ideas?
I have found working solution:
int volume { get; set; }
public Constructor(){
InitializeComponent();
myVlcControl.VideoOutChanged += myVlcControl_VideoOutChanged;
}
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
this.volume = (int)numericUpDown1.Value;
myVlcControl.Audio.Volume = volume;
}
void vlcPlayer_VideoOutChanged(object sender, VlcMediaPlayerVideoOutChangedEventArgs e)
{
myVlcControl.Audio.Volume = volume;
}
This seems to work for both file and stream.
How would this work. Default 40, if you need volume changed at start of playback:
myVlcControl.Audio.Volume = volume;
and add basic function to MediaChanged event to verify that volume is always correct. Also, might be good idea to add slider from 0-200 and default is to 40 -> ValueChanged event -> volume = volumeSlider.Value;
private static int volume = 40;
private void volume_changer(int vol)
{
volume = vol;
}
private void preview_Player_MediaChanged(object sender, Vlc.DotNet.Core.VlcMediaPlayerMediaChangedEventArgs e)
{
preview_Player.Audio.Volume = volume;
}
My working solution is same as Marcin Bigorge explained above.
vlcControl.TimeChanged += vlcControl_VideoOutChanged;
private void vlcControl_VideoOutChanged(object sender, VlcMediaPlayerTimeChangedEventArgs e)
{
vlcControl.Audio.Volume = volume;
}
All these comes from the idea that i want to use the SerialPort class in .Net , but the only way is by calling dll . Because i can only get interfaces from the program calling this dll. mycode is below.
i wrote a class about serialport,
public class CommClass
{
public SerialPort _port;
private string _receivedText;
public string receivedText
{
get { return _receivedText; }
set
{
_receivedText = value;
}
}
public CommClass(string _pname)
{
portList = SerialPort.GetPortNames();
_port = new SerialPort(portList[0]);
if (portList.Length < 1)
_port= null;
else
{
if(portList.Contains(_pname.ToUpper()))
{
_port = new SerialPort(_pname);
_port.DataReceived += new SerialDataReceivedEventHandler(com_DataReceived);
}
}
}
private void com_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
string indata = _port.ReadExisting();
receivedText = indata;
}
}
from Bytestoread i can see there r data coming in and i can get data from port.ReadExisting(), but receivedText did not change ,it did not hit the SerialDataReceived event . Is my way wrong?any suggestion?thanks
i created a dll from CommClass ,then i call it in my winform program which has a button and a textbox . Clicking the button , then i initialize the port
public Form1()
{
InitializeComponent();
}
public CommClass mycom;
private void button1_Click(object sender, EventArgs e)
{
mycom = new CommClass("com3");
mycom._port.Open();
textbox.Text=mycom.receivedText;//i add a breakpoint at this line ,
}
when hitting it , i check mycom._port.PortName is "com3", its IsOpen() is "Open" , i use virtual port to send data . i send "1111",then check the mycom._port.BytestoRead is 4, and mycom._port.ReadExisting() is "1111", but mycom.receivedText is null. My puzzle is that i have no idea when the data is coming . How to use the DataReceived event in my winform without code "using System.Io.Ports",just with reference CommClass.dll. Did i make it clear? Thanks for help.
mycom._port.Open();
textbox.Text=mycom.receivedText;//i add a breakpoint at this line ,
That code cannot work, it is a threading race bug. The DataReceived event does not fire instantly after you open the port. It will take a microsecond or so, give or take. A threadpool thread has to get started to fire the event. And of course the device actually has to send something, they usually only do so when you transmit something first.
Which clearly did not happen, your DataReceived event handler has a bug as well. It is not allowed to update the Text property of a control in that event since it runs on a worker thread. Your program will bomb with an InvalidOperationException.
You'll have to write something like this instead:
private void com_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
string indata = _port.ReadExisting();
this.BeginInvoke(new Action(() => {
textbox.AppendText(indata);
}));
}
With the additional stipulation that you must not leave it this way, updating the Text property of a TextBox and making it visible on the screen is an expensive operation that's going to turn your user interface catatonic when the device starts transmitting data at a high rate.
So, I'm trying to develop a simple application in visual C# which gets data from serial port and displays it in a textbox (to monitor temperature). I'm acquiring and displaying the data successfully, using the DataReceived event to update a global string variable and a timer to update the text field on my text box, as shown:
private void port_DataReceived_1(object sender, SerialDataReceivedEventArgs e)
{
try
{
globalVar.updateTemp = port.ReadLine(); //This is my global string
}
catch (IOException)
{
}
catch (InvalidOperationException)
{
}
catch (TimeoutException)
{
}
}
private void timer1_Tick(object sender, EventArgs e)
{
tempDisplayBox.Text = globalVar.updateTemp; //This is my textbox updating
}
The only issue I have is that the value shown in the textbox keeps flashing, making it hard to read. My timer is set to trigger every 10 ms (which should be fast enough, right?). Is there any way to make it more stable? I realize this may be a newb question, but to be fair I am a newb :) Any help is appreciated! Thanks!
Do you really need it updating every 10ms? What about every 500 ms or if not that then 100ms. 100ms will require your update method run 10 times less and therefore update 10 times less. The flickering you are expiriencing is due to the refresh speed. You could create custom method which will only update the temp only when target Label or textBox value is different than source port. But that will only sort the flickering when temp is steady, when temp will start vary it will bring back the flickering. Good luck ;-)
UPDATE
Hi I tried to reproduce the conditions and could not make my textbox nor Label flash. The way I tested it was by assigning int ntick = 0; and then increment the ++ntick; inside of the timer_tick method. The results didn't make any of the controls flash and were updated even every milisecond at some point. I also tried string.Format to put some load on the method. Is your app responsive?
The trick is to use double buffering. This way the operating system will redraw the Control off-screen, and only show the control when it is fully redrawn.
I have had the same problem, and solved it by extending the TextBox control like this:
public FastLogBox()
{
InitializeComponent();
_logBoxText = new StringBuilder(150000);
timer1.Interval = 20;
timer1.Tick += timer1_Tick;
timer1.Start();
SetStyle(ControlStyles.DoubleBuffer, true);
}
void timer1_Tick(object sender, EventArgs e)
{
if (_timeToClear)
{
_logBoxText.Clear();
_timeToClear = false;
}
if (_logQueue.Count <= 0) return;
while (!_logQueue.IsEmpty)
{
string element;
if (!_logQueue.TryDequeue(out element)) continue;
{
_logBoxText.Insert(0, element + "\r\n");
}
}
if (_logBoxText.Length > 150000)
{
_logBoxText.Remove(150000, _logBoxText.Length - 150001);
}
Text = _logBoxText.ToString();
}
public new void Clear()
{
_timeToClear = true;
while (!_logQueue.IsEmpty)
{
string element;
_logQueue.TryDequeue(out element);
}
}
public void AddToQueue(string message)
{
_logQueue.Enqueue(message);
}
}
I also use a timer and a concurrentQueue to avoid using Invoke to update the control from another thread. I also use a StringBuilder to prepare the string before putting it into the TextBox. StringBuilder is faster when building larger strings.
You can use ReadExisting() to read the whole data at a time.
You need to handle DataReceived Event of SerialPort
serialPort1.ReadExisting();
Sample:
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
String myData=serialPort1.ReadExisting();
}
Example Code: Here i would like to show you the code to Read Data(RFID Tag Code which is basically of length 12)
String macid = "";
private void DoWork()
{
Invoke(
new SetTextDeleg(machineExe ),
new object[] { macid });
macid = "";
}
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
string str1;
macid += serialPort1.ReadExisting();
if (macid.Length == 12)
{
macid = macid.Substring(0, 10);
Thread t = new Thread(new ThreadStart(DoWork));
t.Start();
}
}
public void machineExe(string text)
{
TextBox1.Text=text;
}
Thank you so much for the answers! I found a way to work around this issue:
Instead of replacing the contents of my textbox by rewriting the TextBox.Text property - which, as HenningNT implied, refreshes the control and causes the flickering - I'm now using the TextBox.AppendText method. Though, as I want to display only one line of data at a time, I use the textbox in multiline mode and the Environment.NewLine to jump to a new line before appending the text. As for the method of updating, I've gone back to using the timer because with the invoke method was crashing my application when I close the form, for some reason. Also, enabling double buffering didn't do me much good, although I guess I was doing it wrong... It still flickers a bit, but it's much better now :) I know this is not really a perfect solution (much more of a workaround), so I'll keep looking for it. If I find it, I'll be sure to update it here ;) My code:
private void timer1_Tick(object sender, EventArgs e) //Timer to update textbox
{
if (tempDisplayBox.Text != globalVar.updateTemp) //Only update if temperature is different
{
try
{
tempDisplayBox.AppendText(Environment.NewLine);
tempDisplayBox.AppendText(globalVar.updateTemp);
}
catch (NullReferenceException)
{
}
}
}
Life status of device connected via serial port.
Hello everyone.
How can I check if the device responds to the request? I'm googling this for couple days and tried lot of solutions also from SO, but nothing gave me results that I've expected. After lot of tries I'm in point described below. I think I'm very close but now I need little help, so thanks for every answer in advance.
The current situation
What am I doing right now is very simple. First of all I'm opening serial port serialPort.Open() at very beggining of app (data is receiving almost all the application running time).
As this is just an example in my form is only one label called labelStatus and labelStatus.Text = "Not connected"
Next I'm adding a timer and it's tick method, that contains execute of serialPort.Write(). Timer Interval is set to 100 if that matters.
private void timer_Tick(object sender, EventArgs e)
{
if (serialPort.IsOpen)
{
serialPort.WriteLine("r"); //I'm sending "r" message and device send data back
}
}
Next step is create DataReceived event like below (very simplified version, in my app received data is parsing to floats and storing in array, but it's just to show the problem)
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
string someVariable = serialPort.ReadLine();
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Connected"));
//If i received something that means the device is plugged in and connection is correct (still very simplified)
}
One last thing is create ErrorReceived method.
private void serialPort_ErrorReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Not connected"));
}
Untill now everything works brilliant. Sending data works. DataReceived event is executig each 100 miliseconds when data is send. My data is received properly with no problems. When I start application labelStatus text is "Not connected" (device cable is not plugged in). When I plugged in device labelStatus text changing to "Connected". But now when I plugged of cable ErrorReceived event is not executing and labelStatus text is still "Connected". So as I've asked before: How can I check is device still connected to computer? (Or maybe: how to execute ErrorReceived event, when data is not receiving?).
Note: Serial port ReadTimeout is set to 300 miliseconds.
What have I tried
I've tried lot of things but this one in my head seems to should work but doesn't.
I've modified DataReceived event and I've put serialPort.ReadLine() into try/catch block with TimeoutException where I've tried to manually execute ErrorReceived method like below
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
try
{
string someVariable = serialPort.ReadLine();
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Connected"));
//If i received something that means the device is plugged in and connection is correct (still very simplified)
}
catch (TimeoutException)
{
serialPort_ErrorReceived(null, null);
}
}
I was hoping that will work like I want.
BTW. Sorry for my English. It's not perfect, but I do my best. Cheers!
Listen to the WM_DEVICECHANGE event that will be fired when a device is removed or inserted.
Here is an example of a implementation and some more information:
Detect serial port insertion/removal
http://www.codemiles.com/download/file.php?id=719 (USB Sample)
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363480(v=vs.85).aspx
This is solution in my case
Regarding to Martjin's answer i need to further explain my situation. First of all I want to say that I'm not installing any hardware into my computer, so in my opinion WM_DEVICECHANGE event was not what i need (but of course thanks for information, I've learned something new). Application is reading data from scale. Scale after plug into com port is not sending any data and actually there's no communication between it and computer at all. The only way to read data is to send request to scale, so I have to rely on that.
First try
The plan:
Add two static int fields (flags) checkOld and checkNew,
increment checkNew in DataReceived, check in timer Tick method
is checkOld is equal to checkNew. If true that means checkNew
was not increment, and that means DataReceived was not executed.
`
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
checkNew++;
string someVariable = serialPort.ReadLine();
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Connected"));
//If i received something that means the device is plugged in and connection is correct (still very simplified)
}
private void timer_Tick(object sender, EventArgs e)
{
if (serialPort.IsOpen)
{
serialPort.WriteLine("r"); //I'm sending "r" message and device send data back
}
if (checkOld == checkNew)
{
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Not connected"));
}
}
`
The plan was good but when I've tested it result was not even good. What happened? Actually device status was blinking connected-not connected-connected-not connected etc. I've wrote some data to output and get answer. The timer was looping so fast that DataReceived event could not always increment checkNew value.
Final solution
Based on what I had at the moment I've decided to add some little changes. Instead of comparing two integers values try to collect couple last values ad check if all were the sem or not.
The plan:
Add three static fields: first six elements array of integers
statusArray, second integer index with value equals to 6 (last
element of array + 1), third integer checkNew,
increment checkNew in
DataReceived event,
in timer Tick event fill array to index,
decrement index value untill whole array is filled, and if index == 0 reset index value to
6,
and last check if last six values of checkNew, stored in
statusArray are the same. If true that means DataReceived did not
executed six times in a row, and now I can be sure that connection is
lost.
`
static int index = 6;
static int checkNew = 0;
static int[] statusArray = {0,0,0,0,0,0};
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
checkNew++;
string someVariable = serialPort.ReadLine();
labelStatus.Invoke((MethodInvoker)(() => labelStatus.Text = "Connected"));
//If i received something that means the device is plugged in and connection is correct (still very simplified)
}
private void timer_Tick(object sender, EventArgs e)
{
if (serialPort.IsOpen)
{
serialPort.WriteLine("r"); //I'm sending "r" message and device send data back
}
if (index == 0)
index = 6;
index--;
int value = statusArray[index] = checkNew;
}
`
I have an API (dll) that collects stock ticks via an event mechanism. Such as below:
...
using MT4API;
public partial class Blue : Form
{
...
public Blue()
{
...
string symbol = "GBPUSD";
MT4DDE dde = new MT4DDE("");
dde.OnQuote += new System.EventHandler<QuoteEventArgs>(MT_OnQuote);
dde.Connect();
dde.Subscribe(symbol);
....
The idea is that on each chart tick I get an event. here is the event handler code:
private static void MT_OnQuote(object sender, QuoteEventArgs args)
{
GlobalClass.Ask = args.Ask;
GlobalClass.Bid = args.Bid;
// I have back ground worker code that updatestables from the global class
}
This all works fine. So long as I do not touch any other buttons on the form UI. As soon as I click a button on the form of the UI... I no longer receive events from my API, the UI application functions normally, but with no data from the API.
Why do events from the UI stop any further events coming from the API event?
Any idea whats going on here? Or suggestions how to design this?
Does the same problem occur if you comment out your code that updates the tables from the global object? and if you comment out the background worker?
It would be a good idea to distinguish if the event stops being fired just after you press some button on the UI, or if it stops being fired only after some line of code you wrote is being executed.
In order to be able to help you, we would need to know how the event on the MT4DDE class is triggered.
If you have the code for this class, posting it would help.
If you don't you may want to use a tool such as Reflector to decompile the assembly into C# and see what the MT4DDE class is doing that might cause it to stop invoking the event.
In addition, if you are doing anything related to background threads, or if you're doing anything unusual with your application's main message loop, it would be a good idea to mention it here.
I have tried to use the invoke command, it works, but after a few events it stops...here is the code isolated:
using MT4API;
namespace WindowsFormsApplication1
{
public delegate void UpdateTextCallback(double ask, double bid);
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
string symbol = "GBPUSD";
MT4DDE dde = new MT4DDE("");
dde.OnQuote += new EventHandler<QuoteEventArgs>(MT_OnQuote);
dde.Connect();
dde.Subscribe(symbol);
}
private void updateTickDisplay(double ask, double bid)
{
textBox1.Text = ask.ToString();
textBox2.Text = bid.ToString();
}
private void button1_Click(object sender, EventArgs e)
{
this.Close();
}
private void MT_OnQuote(object sender, QuoteEventArgs args)
{
BeginInvoke(new UpdateTextCallback(this.updateTickDisplay),
new object[] { args.Ask, args.Bid });
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
textBox3.Text = textBox1.Text;
}
}
}
The only difference from the real code is that I am using a data grid....as opposed to a text field. But it is clear that the UI blocks somehow the new events. It is strange that I get about 5 to 10 events and then it just stops. Strange. Any ideas on a differnet design?