Methods to use the serial port in multiple forms - vb.net

Question

I'm designing a windows userform to interact with a microcontroller through the serial port.
The GUI includes multiple userforms which will use the same serialport. I researched how to do that and I found different ideas. Some I don't know if it works the others I'm not sure how to implement it in code. Let's say I have
Form1: Start.vb
Form2: Shield1.vb
1) Can I declare the serial port in the start userform as:
Public Shared SerialPort1 As New System.IO.Ports.SerialPort
And use it in the other forms ?
2) First alternative: Use a Module to declare a new Serialport
Module Module1
Public WithEvents mySerialPort1 As New IO.Ports.SerialPort
Private Sub mySerialPort1_DataReceived(sender As Object, _
e As System.IO.Ports.SerialDataReceivedEventArgs) _
Handles mySerialPort1.DataReceived
End Sub
End Module
Is this method right? If yes How do I use it in the code of my forms ? How to include the DataReceived Event in the code of the forms ?
3) Second alternative: Constructor of the Serialport in the start form and then pass the data to the other forms as mentionned in this post: Alternate Solution 1
private void OnSetup(object sender, EventArgs e)
{
this.port = new SerialPort(...);
// TODO: initialize port
Form2 f2 = new Form2(this.port);
f2.Show();
Form3 f3 = new Form3(this.port);
f3.Show();
Form4 f4 = new Form4(this.port);
f4.Show();
}
Are then the Events also included ? How do I use them?
4) Third alternative: Use a static class like done in this solution:
Alternate Solution 2
Is the code written in C# here right ? I'm writing my programm in VB.net but I could take this as a reference.
Which is the recommended solution for a beginner ? Could you please write it in a small code if you have another suggestion or a correction ?
I apologize in advance for any ambiguity or falsly used terms.
Thanks you!

Answer 1

I would follow the "Singleton" design pattern, which ensures that only one instance of a class is created. Here is a well-accepted template for such a class:
Public NotInheritable Class MySerial
Private Shared ReadOnly _instance As New Lazy(Of MySerial)(Function() New
MySerial(), System.Threading.LazyThreadSafetyMode.ExecutionAndPublication)
Private Sub New()
End Sub
Public Shared ReadOnly Property Instance() As MySerial
Get
Return _instance.Value
End Get
End Property
End Class
In the New() method you should set up your serial port as you need to. Then no matter where you need to use the port, you make your references to the Instance:
Dim singletonSerial As MySerial = MySerial.Instance
This is the canonical pattern to ensure that you have only one copy of an object without resorting to static classes. It's a design pattern that dates back more than 20 years and still works great when you need exactly one copy of an object.

Answer 2

I found this very helpful example of a sigleton C# class for serial port:
C# Singleton Example
As a beginner I used a Code converter to have it in VB.Net. Can you guys let me know if the resulting code is correct and I can use it ? Thanks a lot!!
Imports System
Imports System.IO
Imports System.IO.Ports
Imports System.Threading
Namespace HeiswayiNrird.Singleton
Public NotInheritable Class SerialPortManager
Private Shared lazy As Lazy(Of SerialPortManager) = New Lazy(Of SerialPortManager)(() => { }, New SerialPortManager)
Public Shared ReadOnly Property Instance As SerialPortManager
Get
Return lazy.Value
End Get
End Property
Private _serialPort As SerialPort
Private _readThread As Thread
Private _keepReading As Boolean
Private Sub New()
MyBase.New
Me._serialPort = New SerialPort
Me._readThread = Nothing
Me._keepReading = false
End Sub
''' <summary>
''' Update the serial port status to the event subscriber
''' </summary>
Public Event OnStatusChanged As EventHandler(Of String)
''' <summary>
''' Update received data from the serial port to the event subscriber
''' </summary>
Public Event OnDataReceived As EventHandler(Of String)
''' <summary>
''' Update TRUE/FALSE for the serial port connection to the event subscriber
''' </summary>
Public Event OnSerialPortOpened As EventHandler(Of Boolean)
''' <summary>
''' Return TRUE if the serial port is currently connected
''' </summary>
Public ReadOnly Property IsOpen As Boolean
Get
Return Me._serialPort.IsOpen
End Get
End Property
''' <summary>
''' Open the serial port connection using basic serial port settings
''' </summary>
''' <param name="portname">COM1 / COM3 / COM4 / etc.</param>
''' <param name="baudrate">0 / 100 / 300 / 600 / 1200 / 2400 / 4800 / 9600 / 14400 / 19200 / 38400 / 56000 / 57600 / 115200 / 128000 / 256000</param>
''' <param name="parity">None / Odd / Even / Mark / Space</param>
''' <param name="databits">5 / 6 / 7 / 8</param>
''' <param name="stopbits">None / One / Two / OnePointFive</param>
''' <param name="handshake">None / XOnXOff / RequestToSend / RequestToSendXOnXOff</param>
Public Sub Open(Optional ByVal portname As String = "COM1", Optional ByVal baudrate As Integer = 9600, Optional ByVal parity As Parity = Parity.None, Optional ByVal databits As Integer = 8, Optional ByVal stopbits As StopBits = StopBits.One, Optional ByVal handshake As Handshake = Handshake.None)
Me.Close
Try
Me._serialPort.PortName = portname
Me._serialPort.BaudRate = baudrate
Me._serialPort.Parity = parity
Me._serialPort.DataBits = databits
Me._serialPort.StopBits = stopbits
Me._serialPort.Handshake = handshake
Me._serialPort.ReadTimeout = 50
Me._serialPort.WriteTimeout = 50
Me._serialPort.Open
Me.StartReading
Catch As IOException
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("{0} does not exist.", portname))
End If
Catch As UnauthorizedAccessException
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("{0} already in use.", portname))
End If
Catch ex As Exception
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, ("Error: " + ex.Message))
End If
End Try
If Me._serialPort.IsOpen Then
Dim sb As String = StopBits.None.ToString.Substring(0, 1)
Select Case (Me._serialPort.StopBits)
Case StopBits.One
sb = "1"
Case StopBits.OnePointFive
sb = "1.5"
Case StopBits.Two
sb = "2"
End Select
Dim p As String = Me._serialPort.Parity.ToString.Substring(0, 1)
Dim hs As String = "No Handshake"
'TODO: Warning!!!, inline IF is not supported ?
(Me._serialPort.Handshake = Handshake.None)
Me._serialPort.Handshake.ToString
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("Connected to {0}: {1} bps, {2}{3}{4}, {5}.", Me._serialPort.PortName, Me._serialPort.BaudRate, Me._serialPort.DataBits, p, sb, hs))
End If
If (Not (OnSerialPortOpened) Is Nothing) Then
OnSerialPortOpened(Me, true)
End If
Else
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("{0} already in use.", portname))
End If
If (Not (OnSerialPortOpened) Is Nothing) Then
OnSerialPortOpened(Me, false)
End If
End If
End Sub
''' <summary>
''' Close the serial port connection
''' </summary>
Public Sub Close()
Me.StopReading
Me._serialPort.Close
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, "Connection closed.")
End If
If (Not (OnSerialPortOpened) Is Nothing) Then
OnSerialPortOpened(Me, false)
End If
End Sub
''' <summary>
''' Send/write string to the serial port
''' </summary>
''' <param name="message"></param>
Public Sub SendString(ByVal message As String)
If Me._serialPort.IsOpen Then
Try
Me._serialPort.Write(message)
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("Message sent: {0}", message))
End If
Catch ex As Exception
If (Not (OnStatusChanged) Is Nothing) Then
OnStatusChanged(Me, String.Format("Failed to send string: {0}", ex.Message))
End If
End Try
End If
End Sub
Private Sub StartReading()
If Not Me._keepReading Then
Me._keepReading = true
Me._readThread = New Thread(ReadPort)
Me._readThread.Start
End If
End Sub
Private Sub StopReading()
If Me._keepReading Then
Me._keepReading = false
Me._readThread.Join
Me._readThread = Nothing
End If
End Sub
Private Sub ReadPort()
While Me._keepReading
If Me._serialPort.IsOpen Then
'byte[] readBuffer = new byte[_serialPort.ReadBufferSize + 1];
Try
'int count = _serialPort.Read(readBuffer, 0, _serialPort.ReadBufferSize);
'string data = Encoding.ASCII.GetString(readBuffer, 0, count);
Dim data As String = Me._serialPort.ReadLine
If (Not (OnDataReceived) Is Nothing) Then
OnDataReceived(Me, data)
End If
Catch As TimeoutException
End Try
Else
Dim waitTime As TimeSpan = New TimeSpan(0, 0, 0, 0, 50)
Thread.Sleep(waitTime)
End If
End While
End Sub
End Class
End Namespace