Visual Basic .NET

The event message routine has the following format.

When Using WndProc

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

m.Msg
The message number is passed.

m.WParam
The ID is passed to the lower 2 bytes. The upper two bytes are not currently used.

m.LParam
Parameters specific to each event are passed.

Message Processing Example 1
If there is only one device that uses the event, the device's decision by ID is not particularly necessary. The following code shows an example of displaying a message box when an event occurs.

Select Case Message
Case AIOM_AOE_START
    MsgBox "Device ID: " & m.WParam & Chr$(13), , "Generating start"
Case AIOM_AOE_RPTEND
    MsgBox "Device ID: " & m.WParam & Chr$(13) & "Repeat Times : " & m.LParam, , "Repeat end"
Case AIOM_AOE_END
    MsgBox "Device ID: " & m.WParam & Chr$(13) & "Generating Times : " & m.LParam, , "Generating end"
Case AIOM_AOE_DATA_NUM
    MsgBox "Device ID: " & m.WParam & Chr$(13) & "Generating Times : " & m.LParam, , "Data stored"
Case AIOM_AOE_SCERR
    MsgBox "Device ID: " & m.WParam & Chr$(13) & "Generating Times : " & m.LParam, , "Generating clock period error"
Case AIOM_AOE_ADERR
    MsgBox "Device ID: " & m.WParam & Chr$(13) & "Generating Times : " & m.LParam, , "DA conversion error"
End Select

Message Processing Example 2
When using events on multiple devices, you need to decide which device generated event. The following code is an example of using events on two devices (ID1 and ID2).

If m.WParam = ID1 Then
    Select Case Message
    Case AIOM_AOE_START
        MsgBox "Device 1" & Chr$(13), , "Generating start"
    Case AIOM_AOE_RPTEND
        MsgBox "Device 1" & Chr$(13) & "Repeat Times : " & m.LParam, , "Repeat end"
    Case AIOM_AOE_END
        MsgBox "Device 1" & Chr$(13) & "Generating Times : " & m.LParam, , "Generating end"
    Case AIOM_AOE_DATA_NUM
        MsgBox "Device 1" & Chr$(13) & "Generating Times : " & m.LParam, , "Data stored"
    Case AIOM_AOE_SCERR
        MsgBox "Device 1" & Chr$(13) & "Generating Times : " & m.LParam, , "Generating clock period error"
    Case AIOM_AOE_ADERR
        MsgBox "Device 1" & Chr$(13) & "Generating Times : " & m.LParam, , "DA conversion error"
    End Select
Else
    Select Case Message
    Case AIOM_AOE_START
        MsgBox "Device 2" & Chr$(13), , "Generating start"
    Case AIOM_AOE_RPTEND
        MsgBox "Device 2" & Chr$(13) & "Repeat Times : " & m.LParam, , "Repeat end"
    Case AIOM_AOE_END
        MsgBox "Device 2" & Chr$(13) & "Generating Times : " & m.LParam, , "Generating end"
    Case AIOM_AOE_DATA_NUM
        MsgBox "Device 2" & Chr$(13) & "Generating Times : " & m.LParam, , "Data stored"
    Case AIOM_AOE_SCERR
        MsgBox "Device 2" & Chr$(13) & "Generating Times : " & m.LParam, , "Generating clock period error"
    Case AIOM_AOE_ADERR
        MsgBox "Device 2" & Chr$(13) & "Generating Times : " & m.LParam, , "DA conversion error"
    End Select
EndIf