Private _receivenow As AutoResetEvent
Private port As SerialPort
Private Event _formeventhandler As SerialDataReceivedEventHandler

Public Custom Event FormEventHandler As SerialDataReceivedEventHandler
AddHandler(value As SerialDataReceivedEventHandler)
AddHandler _formeventhandler, value
AddHandler port.DataReceived, AddressOf _formeventhandler
End AddHandler

RemoveHandler(value As SerialDataReceivedEventHandler)
RemoveHandler _formeventhandler, value
RemoveHandler port.DataReceived, AddressOf _formeventhandler
End RemoveHandler

RaiseEvent()

End RaiseEvent

End Event

Public Function ExecuteCommand(command As String, timeout As Integer) As String

RemoveHandler port.DataReceived, AddressOf _formeventhandler
AddHandler port.DataReceived, AddressOf port_DataReceived

port.DiscardOutBuffer()
port.DiscardInBuffer()
_receivenow.Reset()
port.Write(command & vbCr)

Dim input As String = ReadResponse(timeout)
If (input.Length = 0) OrElse ((Not input.EndsWith(vbCr & vbLf & "> ")) AndAlso (Not input.EndsWith(vbCr & vbLf & "OK" & vbCr & vbLf))) Then
Throw New ApplicationException("No success message was received.")
End If

RemoveHandler port.DataReceived, AddressOf port_DataReceived
AddHandler port.DataReceived, AddressOf _formeventhandler

Return input
End Function

Private Sub port_DataReceived(sender As Object, e As System.IO.Ports.SerialDataReceivedEventArgs) Handles port.DataReceived
Dim buffer As String = String.Empty
Dim read As String = port.ReadExisting()
buffer += read
Me.Invoke(New RetrieveDataInvoker(AddressOf RetrieveData), buffer)
End Sub

saya rada bingung menjelaskannya tapi saya dapat soruce ini menggunakan c# dan mau di convert ke vb.net tapi gak bisa bisa soruce asli seperti ini

AutoResetEvent _receivenow;
SerialPort port;

private event SerialDataReceivedEventHandler _formeventhandler;
public event SerialDataReceivedEventHandler FormEventHandler
{
add
{
_formeventhandler += value ;
port.DataReceived += _formeventhandler;
}
remove
{
_formeventhandler -= value;
port.DataReceived -= _formeventhandler;
}
}

public string ExecuteCommand(string command, int timeout)
{

port.DataReceived -= _formeventhandler;
port.DataReceived += port_DataReceived;

port.DiscardOutBuffer();
port.DiscardInBuffer();
_receivenow.Reset();
port.Write(command + "\r");

string input = ReadResponse(timeout);
if ((input.Length == 0) || ((!input.EndsWith("\r\n> ")) && (!input.EndsWith("\r\nOK\r\n"))))
throw new ApplicationException("No success message was received.");

port.DataReceived -= port_DataReceived;
port.DataReceived += _formeventhandler;

return input;
}

public void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
if (e.EventType == SerialData.Chars)
_receivenow.Set();
}

ada yg bisa bantu klo mau ketemu saya ato ym bisa hub saya di
HP : 08158899672 (lokasi Bogor)
YM : martin_martono
ini libary untuk pembuatan sms gateway dengan .net
mungkin nantinya libry ini juga bisa di gunakan untuk membaca data dari serial port tampa menggunakan fifo buffer.
thx sebelumnya