Option Explicit
'**********************************************************************
'* S4L2 - (Section 4, Lesson 2) USING THE FLUSH ROUTINE
'*        This is the RTDX Host Client for Section 4, Lesson 2
'*
'* This example sends 4 bytes to the target and then flushes the
'* channel.
'**********************************************************************

Const Success = &H0                     ' Method call is valid
Const Failure = &H80004005              ' Method call failed
Const ENoDataAvailable = &H8003001E     ' No data was available.
                                        ' However, more data may be
                                        ' available in the future.
Const EEndOfLogFile = &H80030002        ' No data was available
                                        ' The end of the log file has
                                        ' been reached.

Const VALUE_TO_SEND = 5

Sub main()
    
    Dim rtdx As Object
    Dim data As Long
    Dim bufferstate As Long
    Dim status As Long

    On Error GoTo Error_Handler

    ' Create an instance of the RTDX COM object
    Set rtdx = CreateObject("RTDX")

    ' Open channel ichan for writing
    status = rtdx.Open("ichan", "W")

    If status <> Success Then
        Debug.Print "Opening of channel ichan failed"
        GoTo Error_Handler
    End If

    data = VALUE_TO_SEND
    ' send a 32-bit integer to the target
    status = rtdx.WriteI4(data, bufferstate)

    '******************************************************************
    ' Insert code from Step #3 here - to find out if the target has
    '                                 requested data from the host
    '******************************************************************


    If status <> Success Then
        Debug.Print "Error in call to StatusOfWrite"
        GoTo Error_Handler
    End If

    If bufferstate <= 0 Then

        '**************************************************************
        ' Insert code from Step #4 here - to flush the channel
        '**************************************************************


        If status <> Success Then
            Debug.Print "Error in call to Flush"
            GoTo Error_Handler
        End If
    End If

    If status = Success Then
        Debug.Print "Value " & data & " was sent to the target"
    Else
        Debug.Print "WriteI4 failed"
    End If

    ' Close the channel
    status = rtdx.Close()

    ' Release the reference to the RTDX COM object
    Set rtdx = Nothing
    
    Exit Sub

Error_Handler:
Debug.Print "Error in COM method call"
Set rtdx = Nothing

End Sub