Win Forms UDP application

latika singh

Hi All,

I am trying to establish a connection through UDP to a hardware device I want to talk to. Following is my implementation on the win forms:
I catches exception and gives the error message when I try to send the data. It says: "Cannot send packets to an arbitrary host while connected."

Pl advise.

Try
            Dim dataSend() As Byte = New Byte() {}

            myEP = New IPEndPoint(IPAddress.Parse("192.168.2.50"), 20000)
            myUDP.Connect(myEP)

            If myUDP.Client.Connected Then
                lblStatus.Text = "Connection successful"
            End If

            lblStatus.Text = "Converting Data"
            dataSend = Encoding.ASCII.GetBytes(txtDatatoSend.Text)
            If dataSend.Length = 0 Then
                lblStatus.Text = "Send textbox cannot be left blank"
            Else
                lblStatus.Text = ""
            End If
            If myUDP.Client.Connected Then
                myUDP.Send(dataSend, dataSend.Length, myEP)
            End If
        Catch ex As System.Exception
            MsgBox(ex.ToString)
        End Try

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
As you've already connected to the endpoint, try replacing this line:

myUDP.Send(dataSend, dataSend.Length, myEP)

with this:

myUDP.Send(dataSend, dataSend.Length)
Vulpes14y ago
A Double is represented by 8 bytes in floating point binary notation.

So, if the first (or only) 8 bytes in the Byte array, dataRecv, represent a Double, you can get its value and display it in a textbox as follows:

dataRecv = myUDP.Receive(myEP)
Dim d As Double = BitConverter.ToDouble(dataRecv, 0)
txtReceive.Text = d.ToString()
latika singh14y ago
Hi,

Thanks for the reply! I have another concern. Is there a method to convert the bytes received from UDP into Double and display them in a textbox?

If myUDP.Client.Connected Then
                Dim dataRecv() As Byte = New Byte() {}
                dataRecv = myUDP.Receive(myEP)
                txtReceive.Text = Encoding.ASCII.GetString(dataRecv)
End if

I want to convert this dataRecv into Double and put in a label or textbox.