Serial Port Data Received only working when breakpoint set - vb.net

Question

I have a program that starts an ultrasonic wind gauge and then requests the reading after 5 seconds. When I put a breakpoint in the Data Received handler the data being returned from the wind gauge is processed correctly, however if I do not have the breakpoint in place the data is ignored. The code is as follows (startWG is called when F2 is pressed on the keyboard)
Dim WGCom As New SerialPort
Private Function initWG() As Boolean
Dim WGPort = My.Settings.WGCom
If Not (WGCom.IsOpen) Then
Try
WGCom.PortName = "COM" & WGPort
WGCom.Parity = Parity.Even
WGCom.DataBits = 7
WGCom.StopBits = StopBits.One
WGCom.Handshake = Handshake.None
'WGCom.ReadTimeout = 3000
WGCom.WriteTimeout = 50000
WGCom.Open()
Catch ex As InvalidOperationException
MessageBox.Show(ex.Message)
Catch ex As UnauthorizedAccessException
MessageBox.Show(ex.Message)
Catch ex As System.IO.IOException
MessageBox.Show(ex.Message)
End Try
End If
If (WGCom.IsOpen) Then
Return True
Else
Return False
End If
End Function
#If (WGPort > 0) Then
#End If
'What to do with the wind gauge data when it is received.
Public Sub DataReceivedHandler(
sender As Object,
e As SerialDataReceivedEventArgs)
Dim sp As SerialPort = CType(sender, SerialPort)
Dim indata As String = sp.ReadExisting()
'MsgBox("Seen Data from WG " & indata)
If (indata.Length 0) Then
reading = indata.Substring(plus - 1, 5)
read = True
End If
Catch ex As Exception
End Try
Try
minus = InStr(indata, "-")
If (minus > 0) Then
reading = indata.Substring(minus - 1, 5)
read = True
End If
Catch ex As Exception
End Try
If (read) Then
WGReading = reading
' MsgBox(reading)
WGHasRead = True
read = False
plus = 0
minus = 0
Dim forClass As New WGReads
forClass.Reading = reading
SerialLog.WGReadings.Add(forClass)
RaiseEvent PropertyChanged("DataReceivedHandler", New PropertyChangedEventArgs("LastWG"))
WGFill(wgfield, hjevent)
End If
End Sub
Public Sub WGStart(wg() As String, hjevents As hjCompetition)
wgfield = wg
hjevent = hjevents
If (initWG()) Then
AddHandler WGCom.DataReceived, AddressOf DataReceivedHandler
Dim initBuffer(9) As Byte
initBuffer(0) = &H1
initBuffer(1) = &H13
initBuffer(2) = &H43
initBuffer(3) = &H57
initBuffer(4) = &H49
initBuffer(5) = &H2
initBuffer(6) = &H30
initBuffer(7) = &H35
initBuffer(8) = &H4
Try
WGCom.Write(initBuffer, 0, initBuffer.Length)
Catch ex As System.TimeoutException
End Try
'After init wait for the wind gauge to catch up
System.Threading.Thread.Sleep(100)
Dim outputBuffer1(9) As Byte
outputBuffer1(0) = &H1
outputBuffer1(1) = &H13
outputBuffer1(2) = &H43
outputBuffer1(3) = &H57
outputBuffer1(4) = &H53
outputBuffer1(5) = &H2
outputBuffer1(6) = &H30
outputBuffer1(7) = &H30
outputBuffer1(8) = &H4
Try
WGCom.Write(outputBuffer1, 0, outputBuffer1.Length)
Catch ex As System.TimeoutException
End Try
'Wait for the wind gauge to finish
wait(5500)
'Add a handler for when data is received from the Wind Gauge
AddHandler WGCom.DataReceived, AddressOf DataReceivedHandler
'Get the reading from the wind gauge
Dim getBuffer(9) As Byte
getBuffer(0) = &H1
getBuffer(1) = &H13
getBuffer(2) = &H43
getBuffer(3) = &H57
getBuffer(4) = &H4F
getBuffer(5) = &H2
getBuffer(6) = &H30
getBuffer(7) = &H30
getBuffer(8) = &H4
Try
WGCom.Write(getBuffer, 0, getBuffer.Length)
Catch ex As System.TimeoutException
End Try
'closeCom()
End If
End Sub
It doesn't matter where the breakpoint in the Data Received handler is but as long as there is one. If the breakpoint is in the WGStart Sub it doesn't work either.
Surely a breakpoint should not change the way the program executes?
Thanks in advance for your help.

Answer 1

Adding in a wait(100) has fixed the issue. The code for the wait sub is as follows for others looking for a solution to similar issues
Private Sub wait(ByVal interval As Integer)
Dim sw As New Stopwatch
sw.Start()
Do While sw.ElapsedMilliseconds < interval
' Allows UI to remain responsive
Application.DoEvents()
Loop
sw.Stop()
End Sub