Problem with COM1, errors....

[MotoMan_Yz400]

Hello I'm having an issue with a serial connection program. It connects a motor controller to a computer via RS232.

Here is the code:

Public Class Form1
    Dim COM1 As IO.Ports.SerialPort = My.Computer.Ports.OpenSerialPort("COM1", 38400, IO.Ports.Parity.Odd, 7, IO.Ports.StopBits.One)
    Dim Ring_Vel As Integer = 1
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        'First run setup
        COM1.WriteLine("1PW" & vbCr & vbCr)
        COM1.WriteLine("1RSF" & vbCr)
        COM1.WriteLine("1AC=100000" & vbCr)
        COM1.WriteLine("1VL=" & Ring_Vel & vbCr)
        VScrollBar1.Value = Ring_Vel
        Label3.Text = Ring_Vel
    End Sub
 
  
    Private Sub VScrollBar1_Scroll(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ScrollEventArgs) Handles VScrollBar1.Scroll
        'Speed Controller
        Ring_Vel = VScrollBar1.Value * 1000
        COM1.WriteLine("1VL=" & Ring_Vel & vbCr)
        If Button1.Enabled = False Then COM1.WriteLine("1RFN" & vbCr)
        Label3.Text = VScrollBar1.Value
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'Start Button
        Button1.Enabled = False
        Button2.Enabled = True
        COM1.WriteLine("1RFN" & vbCr)
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        'Stop Button
        Button1.Enabled = True
        Button2.Enabled = False
        COM1.WriteLine("1ST" & vbCr)
    End Sub
End Class

If I change the VScroll1 quickly and often I get this error:
The I/O operation has been aborted because of either a thread exit or an application request.


Why is it doing this? I tried to put the COM1.WriteLine on a timer (.5 sec) so it doesnt overload the buffers or something. And it will still do it.

I dont understand bc I have another program that has a loop, and every cycle of the loop it sends something to the unit. It was able to reach nearly 30 sends per second.