Option Explicit
'**********************************************************************
'* S2L6.bas - (Section 2, Lesson 6) RECEIVING DATA FROM MULTIPLE
'*            CHANNELS
'*            This is the RTDX Host Client for Section 2, Lesson 6
'*
'* This example receives integer values:
'* 3 from channel ochan1
'* 2 from channel ochan2
'* 1 from channel ochan3
'**********************************************************************

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.


'**********************************************************************
' Insert code from Step #3 here - to create a structure to hold the
'                                 attributes
'**********************************************************************
Public Type RTDX_Channel
    obj As Object
    name As String
    type As String
    opened As Boolean
End Type


Sub main()
    '******************************************************************
    ' Insert code here to create an array instance of the type
    ' RTDX_Channel
    '******************************************************************
    Dim rtdx(1 To 3) As RTDX_Channel
    
    Dim data As Integer
    Dim status As Long
    Dim i As Long

    On Error GoTo Error_Handler
    '******************************************************************
    ' Insert code from Step #4 here - to initialize the channel name
    '******************************************************************
    rtdx(1).name = "ochan1"
    rtdx(2).name = "ochan2"
    rtdx(3).name = "ochan3"

 
    '******************************************************************
    ' Insert code from Step #5 here - to create an instance of the RTDX
    '                                 COM Object and open the channels
    '******************************************************************
    For i = LBound(rtdx) To UBound(rtdx)
        rtdx(i).type = "R"
        rtdx(i).opened = False
        Set rtdx(i).obj = CreateObject("RTDX")
        status = rtdx(i).obj.Open(rtdx(i).name, _
            rtdx(i).type)
        If status <> Success Then
            Debug.Print "Opening of channel " & _
                        rtdx(i).name & _
                        " failed"
        Else
            rtdx(i).opened = True
        End If
    Next i


    For i = LBound(rtdx) To UBound(rtdx)
        If rtdx(i).opened Then

            '**********************************************************
            ' Insert code from Step #6 here - to read a 16-bit integer
            '                                 from the target
            '**********************************************************
            status = rtdx(i).obj.ReadI2(data)
            
            Select Case (status)
            
                Case Success
                    Debug.Print "Value " & _
                                data & _
                                " was received from target via channel " & _
                                rtdx(i).name
                Case ENoDataAvailable
                    Debug.Print "No data is currently available"
                Case EEndOfLogFile
                    Debug.Print "End of log file has been detected"
                    rtdx(i).opened = False
                Case Failure
                    Debug.Print "ReadI2 returned failure"
                    rtdx(i).opened = False
                Case Else
                    Debug.Print "Unknown return code"
                    Exit For
            End Select
        End If
    Next i
    
    '******************************************************************
    ' Insert code from Step #7 here - to close the channel and release
    '                                 the reference to the RTDX COM
    '                                 object
    '******************************************************************
    For i = LBound(rtdx) To UBound(rtdx)
        status = rtdx(i).obj.Close()
        Set rtdx(i).obj = Nothing
    Next i
    
    Exit Sub

Error_Handler:
Debug.Print "Error in COM method call"

' Release the reference to the RTDX COM object
For i = LBound(rtdx) To UBound(rtdx)
    Set rtdx(i).obj = Nothing
Next i

End Sub