I want to create an accounting program with c# language.
I want to use a barcode reader for searching products in shop (this is optional for my program)
Now, in main form if seller uses a barcode reader get barcode value for handle method or event;
How can I get barcode value in background of Form (without text box) for handle method or event ?
Note: My barcode reader is HID (USB interface)
The barcode device behaves like a keyboard. When you have focus in a textbox, it sends characters to the textbox as if you typed them from the keyboard.
If you dont want to use a textbox, you'll need to subscribe to a keyboard event handler to capture the barcode stream.
Form1.InitializeComponent():
this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.Form1_KeyPress);
Handler & supporting items:
DateTime _lastKeystroke = new DateTime(0);
List<char> _barcode = new List<char>(10);
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
// check timing (keystrokes within 100 ms)
TimeSpan elapsed = (DateTime.Now - _lastKeystroke);
if (elapsed.TotalMilliseconds > 100)
_barcode.Clear();
// record keystroke & timestamp
_barcode.Add(e.KeyChar);
_lastKeystroke = DateTime.Now;
// process barcode
if (e.KeyChar == 13 && _barcode.Count > 0) {
string msg = new String(_barcode.ToArray());
MessageBox.Show(msg);
_barcode.Clear();
}
}
You'll have to do keep track of the "keystrokes" and look out for the "carriage return" that is sent w/ the barcode stream. That can easily be done in an array. To differentiate between user keystrokes and barcode keystrokes, one dirty trick you can do is keep track of the timing of the keystrokes.
For example, if you get a stream of keystrokes less than 100ms apart ending w/ a carriage return, you can assume it is a barcode and process accordingly.
Alternatively, if your barcode scanner is programmable, you can also send special characters or sequences.
Related
I'm trying to create a Serial Communication tool on MSVS using C#. it communicates with the Photon MCU and a bluetooth dongle.
When the "start" button is pressed, the UI sends a "1" to the Photon which it first sends the current time stamp and starts streaming data from the function generator. When the "stop" button is pressed, It first sends 10 "2"s (due to the timer issue on the photon's end) which the when the Photon receives, it stops transmitting the function generator's data. Then it sleeps for a second and sends a "3" which it sends another current time stamp. Then the UI discards data in the InBuffer and stops reading data.
connectBT is connected with the start button and the disconnectBT is connected with the stop button.
This is the code that I have right now:
SerialPort serial = new SerialPort();
string recieved_data;
int startBuffer = 0;
private void connectBT(object sender, RoutedEventArgs e)
{
startBuffer++; // keep track of BT open counter
if (serial.IsOpen) Debug.WriteLine("BT Open");
// first time BT is open and BT is not open
if (!serial.IsOpen)
{
if (startBuffer == 1)
{
// COM port properties
serial.PortName = "COM7";
serial.BaudRate = 38400;
serial.Handshake = Handshake.None;
serial.Parity = Parity.None;
serial.DataBits = 8;
serial.StopBits = StopBits.One;
serial.ReadTimeout = 200;
serial.WriteTimeout = 50;
serial.Open();
}
startButton.Content = "Recording";
Send_Data("1"); // tell Photon to start sending data
serial.DiscardInBuffer(); // discard whatever is in inbuffer
serial.DataReceived += new SerialDataReceivedEventHandler(Recieve); // start receiving data
}
// after BT has been opened and start button has been pressed again
else if (serial.IsOpen && startBuffer > 1)
{
startButton.Content = "Recording";
Send_Data("1");
serial.DiscardInBuffer();
serial.DataReceived += new SerialDataReceivedEventHandler(Recieve);
}
}
// stop button is pressed
private void disconnectBT(object sender, RoutedEventArgs e)
{
// send "2" ten times to tell photon to stop transmitting function generator data
int i = 0;
while (i < 10)
{
Send_Data("2");
Thread.Sleep(1);
i++;
}
Thread.Sleep(1000);
Send_Data("3"); // send a 3 to tell photon to send the last time stamp
Thread.Sleep(1000);
serial.DiscardInBuffer(); // discard in buffer
serial.DataReceived -= Recieve; // stop receiving data
//serial.Close(); // close BT
startButton.Content = "Start";
}
private void Recieve(object sender, SerialDataReceivedEventArgs e)
{
recieved_data = serial.ReadLine();
Debug.WriteLine(recieved_data);
}
I'm running into an issue where when I press the "stop" button, the last chunk of data that was sent from the bluetooth is lost. I never receive the last time stamp that I'm supposed to have received when the stop button is pressed. According to our math, we're supposed to be receiving 500 points per second (500Hz) but I only receive about 100 of them.
My theory is that the UI is receiving data at a slower (or a delayed) rate and the serial.DiscardInBuffer discard the received data even before that the data can be printed to the Debug output. I know for a fact that all the data between the first and last I receive are all there because of counter values associated with the data packets. Basically if I were to receive 1~500 data points, I only receive 1~100. I've also tried it with just termite with sending 1,2, and 3 as the UI is supposed to be and I get all the data as I need them. I don't close BT on purpose.
What can I do to prevent this data loss? What am I doing wrong in my code that I shouldn't be doing or be doing for the correct bluetooth protocol? This is my first time writing bluetooth code so I'm fairly unfamiliar with it.
Not sure if that's the cause of your problem, but your Receive has a very big pitfall.
You only read one line per Receive event, and on one event there can be more than one line to read, then they are being accumulated and discarded at the end.
ReadLine is meant to be used in a synchronous way like an stream where you read one line, process it then you write, not to be used with the DataReceived event.
You have two options: spin a new thread in a continuous loop reading with serial.ReadLine() (it will block until a new line is available) or the better approach, read the serial buffer on each Receive event.
To do it like that you can do smething like this:
List<byte> tmpBuffer = new List<byte>();
static byte newLineB = Encoding.ASCII.GetBytes("\n")[0];
void Receive(object sender, SerialDataReceivedEventArgs e)
{
lock (tmpBuffer)
{
while (serial.BytesToRead > 0)
{
byte[] segment = new byte[serial.BytesToRead];
serial.Read(segment, 0, segment.Length);
tmpBuffer.AddRange(segment);
ProcessBuffer();
}
}
}
private void ProcessBuffer()
{
int index = 0;
while ((index = tmpBuffer.IndexOf(newLineB)) > -1)
{
string line = Encoding.ASCII.GetString(tmpBuffer.Take(index + 1).ToArray());
//Do whatever you need to do with the line data
Debug.WriteLine(line);
tmpBuffer.RemoveRange(0, index + 1);
}
}
As you can see, the received data is being stored on a temporal list used as a buffer (yes, an array and using Buffer functions would be faster, but for small messages and for simplicity a list is enough for most cases), then the received data is added to the buffer and when there are no more bytes left the list is processed in search of string lines.
Also note the read is in a loop, I have run in cases where there were data received while the function was being executed and no receive event was fired, so the better for this is to create a loop to read while there is still data.
Thank you all for your response, they all helped me reaching the solution for my issue, but in the end what fixed it was delaying the time between sending the "3" and discarding my inBuffer and closing the Receive connection.
async Task DelayBT()
{
await Task.Delay(100);
}
Thread.Sleep() didn't work because of its nature disabling all action within the thread (which I still needed) so this method worked like a charm. I just called await DelayBT where I needed the delay.
Hope this helps anyone running into the same issue as me.
What I am doing:
I am receiving a string of data every second constantly from a serial port. I am processing it and also displaying this string on the rich text box.
Problem:
I want the user to go through the old strings and copy any, but user can't do it because data is coming every second and auto-scrolling occurs.
My desired solution:
I am thinking to have a check-box 'pause'. when user checks it updating of rich text box stops. and user can go in history and copy a string. but in the mean while I don't want to stop the incoming strings from the serial port as I am doing other things as well with the incoming strings.
So when user uncheck 'pause' checkbox, all the strings which had arrived earlier while user had checked' pause' checkbox also appear on rich text box along with new ones.
is there a way to do it ?
Suppose that when you check the Pause button then every incoming text is appended to a StringBuilder instead of the RichTextBox. When the user uncheck the Pause button you copy everything from the StringBuilder to the RichTextBox
// Assume that these are somewhere globals of your forms
RichTextBox rtb = new RichTextBox();
CheckBox chkPause = new CheckBox();
StringBuilder sb = new StringBuilder();
protected void chkPause_CheckedChanged(object sender, EventArgs e)
{
if(!chkPause.Checked)
{
rtb.AppendText = sb.ToString();
// Do not forget to clear the buffer to avoid errors
// if the user repeats the stop/go cycle.
sb.Clear();
}
else
{
// Start a timer to resume normal flow after a timer elapses.
System.Windows.Forms.Timer t = new System.Windows.Forms.Timer();
t.Interval = GetSuspensionMilliseconds();
t.Tick += onTick;
t.Start();
}
}
protected void onTick(object sender, EventArgs e)
{
if (chkPause.Checked)
{
// Set to false when the timing elapses thus triggering the CheckedChanged event
chkPause.Checked = false;
System.Windows.Forms.Timer t = sender as System.Windows.Forms.Timer;
t.Stop();
}
}
now in the point where the incoming data is passed to the RichTextBox you could add
....
string incomingData = ReceiveDataFromSerialPort();
if(chkPause.Checked)
sb.AppendLine(incomingData);
else
rtb.AppendText = incomingData;
I know this is answered question however I want to know hardware required and how to setup.
I am trying to build a take-out's delivery system wherein users call and their phone number gets captured on a WINFORM.
I googled and it says I need to use TAPI API. That's fine but do I need to connect anything to the PC or will just using TAPI work?
This Link explains it in VB.net. I am looking for it in c#.net.
I have also gone through the links provided here.
But nowhere does it explain the setup. So please help.
First thing
See if your hardware supports caller ID
Add the serial port control, set it to whatever comm port your modem is on and watch for the CALLER ID number, then react
To see if your modem supports Caller ID open a serial port terminal (I like putty) and set it to the com port of your modem then call the phone number attached to that that modem, you should see something like RING 5555555555 (where 5555555555 is the phone number of the person calling you)
You may have to turn caller id on for that modem (if so)
1) Open the "Phone And Modem Options" control panel
2) Click the "Modems" tab
3) Select your modem in the list (if it is not already selected)
4) Click the "Properties" button
5) Click the "Advanced" tab
6) Type "#CID=1" into the "Extra initialization commands" edit box
Note: replace "#CID=1" with the command to enable caller id on your modem
Do not include the "AT" part of the command
Do not include the quotes
7) Click OK
8) Click OK
9) restart the computer
Here is some code for interacting with a serial port in c# (incase you need that)
public SerialPort sp;
string dataReceived = string.Empty;
private delegate void SetTextDeleg(string text);
private void FormLoad()
{
sp = new SerialPort("COM1", 9600, Parity.None, 8, StopBits.One);
this.sp.DataReceived += new SerialDataReceivedEventHandler(sp_DataReceived);
sp.Open();
}
void sp_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
try
{
Thread.Sleep(500);
string x = sp.ReadLine(); // will read to the first carriage return
this.BeginInvoke(new SetTextDeleg(si_DataReceived), new object[] { x });
}
catch
{ }
}
private void si_DataReceived(string data)
{
dataReceived = data.Trim();
// Do whatever with the data that is coming in.
}
Also I just searched amazon for "Caller ID Modem" and there seem to be alot for between 10 and 20 dollars (US) that support this exact use. I would recommend the Trendnet TFM-561U
If you are using a phone and fax modem, just plug-in your telephone line into the modem.
Next on your windows form drag-n-drop a SerialPort control and initialize it.
this.serialPort1.PortName = "COM3";
this.serialPort1.BaudRate = 9600;
this.serialPort1.DataBits = 8;
this.serialPort1.RtsEnable = true;
this.serialPort1.DataReceived += serialPort1_DataReceived;
this.serialPort1.Open();
Pass the following command to modem in order to activate Caller-ID
this.serialPort1.WriteLine("AT#cid=1" + System.Environment.NewLine);
Handle its DataReceived event and display the received data
void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
richTextBox1.Text += this.serialPort1.ReadLine();
}
Output:
RING //On 1st Ring
DATE = xxxxx //On 2nd Ring
TIME = xxxx
NMBR = xxxxxxxxx
RING //On 3rd Ring
RING //On 4th Ring
P.S. If the telephone line sends DTMF tones as Caller-ID then you need DTMF to FSK converter to detect the number, or else you will receive the rings but not the number.
How can i read barcode text in background in my C# app? I googled but its of no use. And other resources on stackoverflow are not close to what i need. I want to read barcode in background. And i want to know if the data is coming from barcode or key board. If the data comes from the barcode then it mustnot be displayed on textbox even though the textbox is highlighted. I got similar code for stackoverflow but if there is presence of textbox in the window then the textbox will contain barcode data; which i dont want.
Link : get barcode reader value form background monitoring
DateTime _lastKeystroke = new DateTime(0);
List<char> _barcode = new List<char>(10);
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
// check timing (keystrokes within 100 ms)
TimeSpan elapsed = (DateTime.Now - _lastKeystroke);
if (elapsed.TotalMilliseconds > 100)
_barcode.Clear();
// record keystroke & timestamp
_barcode.Add(e.KeyChar);
_lastKeystroke = DateTime.Now;
// process barcode
if (e.KeyChar == 13 && _barcode.Count > 0) {
string msg = new String(_barcode.ToArray());
MessageBox.Show(msg);
_barcode.Clear();
}
}
Most barcode scanners simply act as keyboard inputs and a quick / easy work around is to place a textbox "Out of sight". An example would be something like this:
// Pseudo code (could be Web, Windows etc)
public void Form1_Load()
{
txtBarcodeScanner.Top = -10000;
txtBarcodeScanner.Left = -10000;
txtBarcodeScanner.Width = 10;
txtBarcodeScanner.Height = 10;
txtBarcodeScanner.Focus();
}
That way the input can be captured by txtBarcodeScanner but will not be visible and the barcode will not seen being captured but will fire KeyDown etc.
Barcode device like keyboard.
1 When entering the barcode, press f12
2 The enter was pressed after inserting the barcode
private void textbox_Keydown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.F12){
Textbox.Focus();
}
if(e.KeyCode == Keys.Enter){
/// after enter barcode
/// save
}
}
check user manual that came with the scanner box.!!
does your barcode scanner supports interfaceType: "usb virtual com port" ?
if yes:
you can do it using serialport() class
1) put your scanner into "usb virtual com port" by scanning that barcode.
it will popup in the device manager.
2) get your baudrate info from device manager
device manager ->
com lpt ports ->
usb serial ch341a (com6)
-> (dobule click) -> "goto tab connection point settings"
there is your baudrate parity etc. info ( write that info to connect port)
3) use this example to do the c# coding. serialport to read data
done!.
I currently have an application I'm writing in c# (using .NET) that requires me to start a timer as soon as a user sees an image on screen up until they respond with a key press.
Now I realise that practically this is very difficult given the monitor input lag and response time, the time the keyboard takes to physically send the message, the OS to process it, etc.
But I'm trying my best to reduce it down to mostly a constant error (the response time results will be used to compare one user to the next so a constant error isn't really an issue). However annoying hurdle is the variable caused by the monitor refresh rate, as I gather when my onPaint message is called and done with, it doesn't mean the image has actually been processed and sent from the graphics buffer?
Unfortunately time restrictions and other commitments would realistically restrict me to continuing this task in c# for windows.
So what I was wondering was if either handling all the drawing in OpenGL or DirectX or better still for me if it is possible to just using either OpenGL or DirectX to create an event when the screen is updated?
Another suggestion given to me previously was regarding V-Sync, if I switch this off is the image sent as soon as it is drawn? as opposed to sending images at a set rate synchronised to the monitor refresh rate?
You must render your graphic in a separate thread in order to:
Use vertical synchronisation to have a precise timing of the effective display of your image.
Get the precise timing of your user input (since user interface is not on the same thread than the render loop.
Initialise Direct3D to enable the VSync during render :
// DirectX example
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.BackBufferCount = 1;
presentParams.PresentationInterval = PresentInterval.One;
device = new Device(...
Perform the render in a separate thread:
Thread renderThread = new Thread(RenderLoop);
renderThread.Start();
shouldDisplayImageEvent = new AutoResetEvent();
Then use the following render loop:
void RenderLoop()
{
while(applicationActive)
{
device.BeginScene();
// Other rendering task
if (shouldDisplayImageEvent.WaitOne(0))
{
// Render image
// ...
userResponseStopwatch = new Stopwatch();
userResponseStopwatch.Start();
}
device.EndScene();
device.Present();
}
}
Then handle the user input :
void OnUserInput(object sender, EventArgs e)
{
if (userResponseStopwatch != null)
{
userResponseStopwatch.Stop();
float userResponseDuration = userResponseStopwatch.ElapsedMillisecond - 1000 / device.DisplayMode.RefreshRate - displayDeviceDelayConstant;
userResponseStopwatch = null;
}
}
You now use the shouldDisplayImageEvent.Set() event trigger to display the image as needed and start the stop watch.
First enable the VSync on your application idle loop :
// DirectX example
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.BackBufferCount = 1;
presentParams.PresentationInterval = PresentInterval.One;
device = new Device(...
Application.Idle += new EventHandler(OnApplicationIdle);
// More on this here : http://blogs.msdn.com/tmiller/archive/2005/05/05/415008.aspx
internal void OnApplicationIdle(object sender, EventArgs e)
{
Msg msg = new Msg();
while (true)
{
if (PeekMessage(out msg, IntPtr.Zero, 0, 0, 0))
break;
}
// Clearing render
// ...
if (displayImage)
{
// Render image
// ...
renderTime = DateTime.now();
}
device.Present();
}
With the vsync enabled, the device.Present function block until the next frame synchronisation, so if you compute the time between renderTime and the user input time and remove the display device delay + 16.67ms you should get your user response delay.