Trouble automating scanning using WIA and VB.NET

**vince8290** · November 28th, 2012, 05:35 PM

I just tried to add a for loop to make it scan from both scanners several times :

Code:

       
Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager
 For k = 1 To 3
            Dim j As String = 1
            For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
[...]
          Next i
        Next k
        DeviceManager1 = Nothing

That showed that the first occurence of the loop works (scans once from each scanner) but that's it, the scanners never scan the second time and start blinking, so basically exactly the same problem.
I also tried to include the Devicemanager declaration in the new loop :

Code:

      
 For k = 1 To 3 
Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager
            Dim j As String = 1
            For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
[...]
          Next i
        DeviceManager1 = Nothing
        Next k

but it did not change anything.

The next thing I did wat to log the events within the loop so that I can know where exactly things stop :

Code:

        Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager
        Dim j As String = 1


        For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
            If DeviceManager1.DeviceInfos(i).Type = 1 Then  'Select only scanners, not webcams etc...

                'startpoint to calculate how long it is to scan
                Dim ScanStart = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)


                'Directory + file
                Dim targetdir = Me.ProjectFolderBox.Text & "\scans\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
                Form2.CurrentActionLabel.Text = "Scanning from scanner #" & j


                Dim Scanner As WIA.Device = DeviceManager1.DeviceInfos(i).connect


                If IsNothing(Scanner) Then
                    Log(Me.logfilename, Now & " | Scanner #" & j & " not found")
                Else
                    Try
                        Dim Img As WIA.ImageFile

                        'log
                        Log(Me.logfilename, Now & " | Scanner #" & j & " | Img initialized")

                        With Scanner.Items(1)
                            .Properties("6146").Value = colorcode '4 is Black-white,gray is 2, color 1 (Color Intent)
                            .Properties("6147").Value = dpi  'dots per inch/horizontal
                            .Properties("6148").Value = dpi 'dots per inch/vertical
                            .Properties("6149").Value = 0 'x point where to start scan
                            .Properties("6150").Value = 0 'y-point where to start scan

                            'Following is A4 paper size. (Not 100% accurate because real A4 Ht errors)
                            .Properties("6151").Value = horizextent 'horizontal exent DPI x inches wide
                            .Properties("6152").Value = vertextent 'vertical extent DPI x inches tall
                            '  .Properties("4104").Value = 8 'bits per pixel

                        End With

                        'log
                        Log(Me.logfilename, Now & " | Scanner #" & j & " | properties initialized")

                        'transfer image
                        Img = Scanner.Items(1).Transfer(fileformat) 'scans the image.

                        'log
                        Log(Me.logfilename, Now & " | Scanner #" & j & " |Transfer done")

                        'kill previous file if exists to avoid errors
                        If System.IO.File.Exists(targetdir) = True Then
                            Kill(targetdir)
                            'log
                            Log(Me.logfilename, Now & " | Scanner #" & j & " | deleted existing " & targetdir)

                        End If

                        Img.SaveFile(targetdir)
                        'log
                        Log(Me.logfilename, Now & " | Scanner #" & j & " | saved " & targetdir)

                        'last scan
                        Form2.LastFileLabel.Text = "\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
                        Form2.LastScanLabel.Text = Now

                    Catch ex As Exception
                        MsgBox(ex.Message)
                    Finally

                        Scanner = Nothing
                    End Try
                End If

                'End time for the scan
                Dim ScanEnd = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)

                'log
                Log(Me.logfilename, Now & " | Scanner #" & j & " | Scanned " & targetdir & " | duration: " & (ScanEnd - ScanStart))

                j = j + 1

            End If

        Next i

Code:

Img = Scanner.Items(1).Transfer(fileformat) 'scans the image.

It looks like WIA is happy to switch from scanner 1 to 2 but refuses to come back to scanner 1 for the next round. also, I should precise, when the second scan is supposed to occur, scanner #2 blinks (and not 1 which surprises me).
Is it possible that scanner#2 is selected as "default scanner" or something like that and if so, is there a way to revert that ?

thanks for your help

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