Serial Communication stops working when loop is started - vb.net

I have problem with serial data communication if I started a loop it is not updating the data from my weighing scale. I can't figure out how to continue the communication as well as to run the loop. The logic of my code will be in the loop so I could check the value from my integer and compare it to the data from serial data (Weighing Scale)
Private Sub conWeight_DataReceived(sender As System.Object, e As System.IO.Ports.SerialDataReceivedEventArgs) Handles conWeight.DataReceived
receivedText(conWeight.ReadExisting())
End Sub
Private Sub receivedText(ByVal [text] As String)
If Me.lblWeight.InvokeRequired Then
Dim x As New SetTextCallback(AddressOf receivedText)
Me.Invoke(x, New Object() {(text)})
Else
Dim reverseString As String = [text]
Dim revString As String = StrReverse(reverseString)
Dim clean As String
clean = revString.Replace("=", "")
Me.lblWeight.Text = clean 'append text
End If
End Sub
'this is part with loop
If binWeight = 0 Then
targetweight = CInt(txtbSilo1.Text) + CInt(txtbSilo2.Text) + CInt(txtbSilo3.Text) + CInt(txtbSilo4.Text)
If CInt(txtbSilo1.Text) > 0 Then
currentWeight = CInt(txtbSilo1.Text)
frmAutomaticControl.conControl.Open()
frmAutomaticControl.conControl.Write("motr1")
frmAutomaticControl.conControl.Close()
MsgBox("check")
Do
If binWeight >= currentWeight Then
frmAutomaticControl.conControl.Open()
frmAutomaticControl.conControl.Write("moto1")
frmAutomaticControl.conControl.Close()
Exit Do
End If
Loop
Else
End If
BunifuFlatButton1.Enabled = True
Else
MsgBox("Empty The Bin")
End If

just a couple of ideas.
1. Throw that part of the code into a background worker.
2. Cheese it and throw in an application.doevents.
3. Create a global variable that'll capture the output of each iteration of your loop that'll then feed it where it needs to go.

Just one line of code is all you need. In your loop put this above everything else.
Application.DoEvents()

Related

Change label text in foreach loop

i want to update a label while a foreach-loop.
The problem is: the program waits until the loop is done and then updates the label.
Is it possible to update the label during the foreach-loop?
Code:
Dim count as Integer = 0
For Each sFile as String in Files
'ftp-code here, works well
count = count+1
progressbar1.value = count
label1.text = "File " & count & " of 10 uploaded."
next
Thanks in advance
Label is not updated because UI thread is blocked while executing your foreach loop.
You can use async-await approach
Private Async Sub Button_Click(sender As Object, e As EventArgs)
Dim count as Integer = 0
For Each sFile as String in Files
'ftp-code here, works well
count = count+1
progressbar1.value = count
label1.text = "File " & count & " of 10 uploaded."
Await Task.Delay(100)
Next
End Sub
Because you will work with Ftp connections, which is perfect candidate for using async-await.
The Await line will release UI thread which will update label with new value, and continue from that line after 100 milliseconds.
If you will use asynchronous code for ftp connection , then you don't need Task.Delay
You've already accepted an answer but just as an alternative a BackgroundWorker can also be used for something like this. In my case the FTP to get the original files happens very quickly so this snippet from the DoWork event is for downloading those files to a printer.
Dim cnt As Integer = docs.Count
Dim i As Integer = 1
For Each d As String In docs
bgwTest.ReportProgress(BGW_State.S2_UpdStat, "Downloading file " & i.ToString & " of " & cnt.ToString)
Dim fs As New IO.FileStream(My.Application.Info.DirectoryPath & "\labels\" & d, IO.FileMode.Open)
Dim br As New IO.BinaryReader(fs)
Dim bytes() As Byte = br.ReadBytes(CInt(br.BaseStream.Length))
br.Close()
fs.Close()
For x = 0 To numPorts - 1
If Port(x).IsOpen = True Then
Port(x).Write(bytes, 0, bytes.Length)
End If
Next
If bytes.Length > 2400 Then
'these sleeps are because it is only 1-way comm to printer so I have no idea when printer is ready for next file
System.Threading.Thread.Sleep(20000)
Else
System.Threading.Thread.Sleep(5000)
End If
i = i + 1
Next
In the ReportProgress event... (of course, you need to set WorkerReportsProgress property to True)
Private Sub bgwTest_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles bgwTest.ProgressChanged
Select Case e.ProgressPercentage
'BGW_State is just a simple enum for the state,
'which determines which UI controls I need to use.
'Clearly I copy/pasted from a program that had 15 "states" :)
Case BGW_State.S2_UpdStat
Dim s As String = CType(e.UserState, String)
lblStatus.Text = s
lblStatus.Refresh()
Case BGW_State.S15_ShowMessage
Dim s As String = CType(e.UserState, String)
MessageBox.Show(s)
End Select
End Sub
Is it not enough to use Application.DoEvents()? This clears the build up and you should be able to see the text fields being updated very quickly.

Does not receive data immediately by using readByte() in serial port

I try to send command to a device and read data back via serial port, however it gives me a weird behavior. I have to sendData() a couple of times(most twice) to get the data. I do not want to use writeLine and I do not write a loop in my code (I have figured out already). My schema works like this. I set ReceivedByteThreshold to 1, so that each time the it receives the data from the device, the ReceivedData event handler is fired. I read one byte at a time. When it read CR, whose ascii is 13, I display the data on the label, but I have to send data (*idn?) more than once(sometimes can be done in one time but not consistent). See the pic for reference. I am not sure why it happens. Thank you in advance
Private Sub DataReceived(sender As Object, e As IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort.DataReceived
Dim ret As Integer
ret = SerialPort.ReadByte()
If ((ret <> 13) And (ret <> 10)) Then
str &= System.Convert.ToChar(ret)
End If
If ret = 13 Then
ret = SerialPort.ReadByte()
If ret = 10 Then
Me.Label2.Text = str
str = ""
End If
End If
End Sub
Sub SendData(ByVal data As String)
Try
SerialPort.Write(data)
Catch ex As Exception
MsgBox("fail to send data")
End Try
End Sub
[update]
I changed my approach. I just used a Do loop but the result is still not consistent. I chose not to use timer any more but just use ReceiveData Event Handler.
Private Sub DataReceived(sender As Object, e As IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort.DataReceived
Dim ret As Integer
Do
ret = SerialPort.ReadByte()
str &= System.Convert.ToChar(ret)
If ret = 13 Then
ret = SerialPort.ReadByte()
If ret = 10 Then
Exit Do
End If
End If
Loop
Me.Label2.Text = str
str = ""
End Sub
I use Docklight to test my code, you can tell sometimes it sends twice in a row before get the data back. I am not if it has race condition issue involved, thank.

Why does Windows.Media.VisualTreeHelper.GetChild(...) exit the sub?

I have a vb application with a listview.
I was testing and ended up with this sub for my dragover event:
Private Sub ListView1_DragOver(sender As Object, e As DragEventArgs) Handles ListView1.DragOver
XToolStripLabel.Text = "X:" & e.X
YToolStripLabel.Text = "Y:" & e.Y
Dim Insertion As Integer = GetInsertion(MousePosition, ListView1)
SelectionTestTSlabel.Text = "SEL " & Insertion
If CurrentlyDragging Then
Dim gr As Graphics = ListView1.CreateGraphics
Windows.Media.VisualTreeHelper.GetChild(New Windows.DependencyObject(), 0) 'I know this seems like it doesn't do much
MsgBox("") 'I actually added this later because the rest of the code did not run normally.
Dim InsertionY As Integer = 24 + (Insertion * TestItemHeight)
If MyLastInsPoint = Insertion Then
Else
ListView1.Refresh()
gr.DrawLine(New Pen(Color.Gray, 3), New Point(0, InsertionY), New Point(ListView1.Width, InsertionY))
End If
MyLastInsPoint = Insertion
End If
End Sub
I realized that the MsgBox("") doesn't popup a message box then i spammed breakpoints on the whole sub.
The sub ran as normal but after this line,
Windows.Media.VisualTreeHelper.GetChild(New Windows.DependencyObject(), 0)
the program returned to the form and did not execute the MsgBox("") line.
What's wrong with the line? The program did not even stop at the End Sub breakpoint.
New Windows.DependencyObject() has no children, so index 0 is not available
See the remaks on MSDN
Call the GetChildrenCount method to determine the total number of
child elements of a parent visual.
The value of reference can
represent either a Visual or Visual3D object, which is why the common
base type DependencyObject is used here as a parameter type.

Collection was modified; enumeration operation may not execute. VB thearding

Here is my code,
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
For Each kthread As Thread In _threads
If kthread.Name = "123" Then
_threads.Remove(kthread)
kthread.Abort()
killedthreads += 1 'a integer
End If
Next
End Sub
I added the killedthreads integer at last as a check, vb executes the whole function good but at the last line it always throw the error said in title.
Not sure why, if killedthreads += 1 is not there then the error goes to kthread.Abort()
I had the same problem with C# with a different app earlier this year.
Edit,
Public Sub KillThread(kThread As Thread)
For i As Integer = (_threads.Count - 1) To 0 Step -1
If _threads.Item(i).Name = kThread.Name Then
_threads.Item(i).Abort()
_threads.RemoveAt(i)
End If
Next
End Sub
I did this code as Eminem said it. This gets in kThread from the running threads if something is not good or it has finished all its functions. But my problem is that, only the first thread that sends it gets abort and removed from list, others seem to get stuck once the first thread is aborted.
I create threads using,
Public Sub multiThreader(int As Integer, link As String)
Dim tCount As Integer = _threads.Count
If tCount >= Form1.ListView1.Items.Count Then
Else
Dim dy As Integer = DateTime.Now.Day
Dim mo As Integer = DateTime.Now.Month
Dim fileNum As String = dy.ToString() + "-" + mo.ToString() + "_" + int.ToString
botThread = New Thread(Sub() MainThread(fileNum, link, botThread, int.ToString()))
botThread.IsBackground = True
botThread.Name = String.Format("AutoBotThread{0}", fileNum)
_threads.Add(botThread)
botThread.Start()
End If
End Sub
and _threads is publicly, Public _threads As New List(Of Thread)
MainThread is a Public Sub which runs functions and gets return and send KillThread under certain conditions.
The problem is that you remove an item from an enumeration, before you finished iterating through it.
It's like trying to iterate from 0 to list.count, when the count changes from an iteration to another. As Bjørn-Roger Kringsjå said, you should do something like this:
For i As Integer = (_threads.count - 1) to 0 Step -1
If _threads.Item(i).Name = "123" Then
_threads.Item(i).Abort
_threads.RemoveAt(i)
killedthreads += 1 'a integer
End If
Next
By using Step -1 you make sure that an Index was out of range error will not occur, and make sure that your operations are fitted, and execute on the right order/item.

VB "Index was out of range, must be non-negative and less than the size of the collection." When trying to generate a random number more than once

So I'm trying to generate a random number on button click. Now this number needs to be between two numbers that are inside my text file with various other things all separated by the "|" symbol. The number is then put into the text of a textbox which is being created after i run the form. I can get everything to work perfectly once, but as soon as i try to generate a different random number it gives me the error: "Index was out of range, must be non-negative and less than the size of the collection." Here is the main code as well as the block that generates the textbox after loading the form. As well as the contents of my text file.
Private Sub generate()
Dim newrandom As New Random
Try
Using sr As New StreamReader(itemfile) 'Create a stream reader object for the file
'While we have lines to read in
Do Until sr.EndOfStream
Dim line As String
line = sr.ReadLine() 'Read a line out one at a time
Dim tmp()
tmp = Split(line, "|")
rows(lineNum).buybutton.Text = tmp(1)
rows(lineNum).buyprice.Text = newrandom.Next(tmp(2), tmp(3)) 'Generate the random number between two values
rows(lineNum).amount.Text = tmp(4)
rows(lineNum).sellprice.Text = tmp(5)
rows(lineNum).sellbutton.Text = tmp(1)
lineNum += 1
If sr.EndOfStream = True Then
sr.Close()
End If
Loop
End Using
Catch x As Exception ' Report any errors in reading the line of code
Dim errMsg As String = "Problems: " & x.Message
MsgBox(errMsg)
End Try
End Sub
Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
rows = New List(Of duplicate)
For dupnum = 0 To 11
'There are about 5 more of these above this one but they all have set values, this is the only troublesome one
Dim buyprice As System.Windows.Forms.TextBox
buyprice = New System.Windows.Forms.TextBox
buyprice.Width = textbox1.Width
buyprice.Height = textbox1.Height
buyprice.Left = textbox1.Left
buyprice.Top = textbox1.Top + 30 * dupnum
buyprice.Name = "buypricetxt" + Str(dupnum)
Me.Controls.Add(buyprice)
pair = New itemrow
pair.sellbutton = sellbutton
pair.amount = amounttxt
pair.sellprice = sellpricetxt
pair.buybutton = buybutton
pair.buyprice = buypricetxt
rows.Add(pair)
next
end sub
'textfile contents
0|Iron Sword|10|30|0|0
1|Steel Sword|20|40|0|0
2|Iron Shield|15|35|0|0
3|Steel Shield|30|50|0|0
4|Bread|5|10|0|0
5|Cloak|15|30|0|0
6|Tent|40|80|0|0
7|Leather Armour|50|70|0|0
8|Horse|100|200|0|0
9|Saddle|50|75|0|0
10|Opium|200|500|0|0
11|House|1000|5000|0|0
Not sure what else to add, if you know whats wrong please help :/ thanks
Add the following two lines to the start of generate():
Private Sub generate()
Dim lineNum
lineNum = 0
This ensures that you don't point to a value of lineNum outside of the collection.
I usually consider it a good idea to add
Option Explicit
to my code - it forces me to declare my variables, and then I think about their initialization more carefully. It helps me consider their scope, too.
Try this little modification.
I took your original Sub and changed a little bit take a try and let us know if it solve the issue
Private Sub generate()
Dim line As String
Dim lineNum As Integer = 0
Dim rn As New Random(Now.Millisecond)
Try
Using sr As New StreamReader(_path) 'Create a stream reader object for the file
'While we have lines to read in
While sr.Peek > 0
line = sr.ReadLine() 'Read a line out one at a time
If Not String.IsNullOrEmpty(line) And Not String.IsNullOrWhiteSpace(line) Then
Dim tmp()
tmp = Split(line, "|")
rows(lineNum).buybutton.Text = tmp(1)
rows(lineNum).buyprice.Text = rn.Next(CInt(tmp(2)), CInt(tmp(3))) 'Generate the random number between two values
rows(lineNum).amount.Text = tmp(4)
rows(lineNum).sellprice.Text = tmp(5)
rows(lineNum).sellbutton.Text = tmp(1)
lineNum += 1
End If
End While
End Using
Catch x As Exception ' Report any errors in reading the line of code
Dim errMsg As String = "Problems: " & x.Message
MsgBox(errMsg)
End Try
End Sub