CODEWITHSUNDEEP
vb.netserial-portbyte
Redder
Redder

Reputation: 146

Working with bytes in VB.NET

I'm developing a project in VB.NET that reads from a SERIAL PORT some info. This info comes in in a pack of 4 bytes. Im able to read the data from the serial port, but what I get is just a pack of 4 numbers.

For example, my readings are:

134 0 0 4
140 0 0 6
141 0 0 5
133 0 0 8
...

The manual explains how to convert this numbers into usable data. Im able to do it over a paper but i dont know how to code this in VB.NET. I dont know how to work at a byte-level.

I attach a picture about the byte's meaning. enter image description here

Upvotes: 0

Views: 2188

Answers (1)

Redder
Redder

Reputation: 146

I got the answer, thanks to user x4rf41

Maybe need some fixes but its what I was looking for.

This is the code:

Private Sub thread_lectura_tarjeta1()

        Dim RXByte As Byte 'byte recived
        Dim RXPacket As List(Of Byte) = New List(Of Byte) 'each reading has 4 bytes
        Dim lectura As Long = 0 'is the FINAL data
        Dim COMPort As SerialPort = ensayo.get_digitalizadores(0).get_puerto_com
        Dim chk_signo As Byte = 0

        While (True)

            lectura = 0

            Do 'each package starts with a byte > 127, because is the only byte that its first bit is 0

                RXByte = COMPort.ReadByte

            Loop Until (RXByte > 127)

            RXByte = RXByte And 127
            RXPacket.Insert(0, RXByte)

            RXByte = COMPort.ReadByte            
            RXPacket.Insert(1, RXByte)

            RXByte = COMPort.ReadByte
            chk_signo = RXByte And 8
            RXPacket.Insert(2, RXByte And 7)

            RXByte = COMPort.ReadByte
            RXPacket.Insert(3, RXByte)

            lectura = RXPacket.Item(0) + RXPacket.Item(1) * 128 + RXPacket.Item(2) * 16384

            'checking sign


            If chk_signo = 8 Then ' negative number

                lectura = (lectura Xor 131071) * -1
            End If



            Sleep(1) 'wait 1 milisecond and read again

        End While
    End Sub

Upvotes: 2

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