Automate scanning from multiple scanners on the same computer using WIA and VB

Question

Hello Stack overflow !

I'm the ultimate beginner in programming. I have some experience in php and vba, doing my own scripts as I need them, especially in excel.

Recently, for a project at works, I need to be able to scan AUTOMATICALLY (say every 2 minutes) from multiple scanners (say 2 for starters) both connected to the same computer. I decided to use this project as a start point for me to get a feeling of Visual Basic. So here we go, I installed visual studio express 2010 and started writing my script trying to find here and there bits of codes that could help me. I found that WIA could help with that (Twain could as well but it seems much more obscure to the newbie I am)

Anyway, I finally came up with an app that is able to automatically scan at the set interval when only one scanner is connected. The trouble arrives when I connect more than one scanner. then, the first scan occurs correctly (Scanner 1 scans, then scanner 2 scans), but when the second scan is supposed to start, nothing happens and the scanners become inaccessible (busy). I though maybe I forgot to "release" or "disconnect" the last scanner used. Or maybe, something remains in the scanner's buffer memory ?

I have been stuck on this issue for the last 3 days and don't know how to make it work.

here is the function that scans : (i don't past the rest as it is the UI and folder management)

 Public Sub scannerloop()

    'format constants
    Const wiaFormatBMP = "{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatPNG = "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatGIF = "{B96B3CB0-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatJPEG = "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatTIFF = "{B96B3CB1-0728-11D3-9D7B-0000F81EF32E}"


    'file format
    Dim fileformat As String
    If Me.FileExt.SelectedItem = "TIF" Then fileformat = wiaFormatTIFF
    If Me.FileExt.SelectedItem = "JPEG" Then fileformat = wiaFormatJPEG
    If Me.FileExt.SelectedItem = "BMP" Then fileformat = wiaFormatBMP
    If Me.FileExt.SelectedItem = "PNG" Then fileformat = wiaFormatPNG
    If Me.FileExt.SelectedItem = "GIF" Then fileformat = wiaFormatGIF

    'colors
    Dim colorcode As Integer
    If Me.Colorbox.SelectedItem = "Black and white" Then colorcode = 4
    If Me.Colorbox.SelectedItem = "Greyscale" Then colorcode = 2
    If Me.Colorbox.SelectedItem = "Colour" Then colorcode = 1

    'Resolution
    Dim dpi As Integer
    dpi = Me.dpiBox.SelectedItem
    Dim horizextent = dpi * 8.2
    Dim vertextent = dpi * 11.6


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

    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

                    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

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

                    'kill previous file if exists to avoid errors
                    If System.IO.File.Exists(targetdir) = True Then
                        Kill(targetdir)
                    End If

                    Img.SaveFile(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



    Next
    DeviceManager1 = Nothing


    Me.CurrFileIndex = Me.CurrFileIndex + 1

    Me.ScanCount = Me.ScanCount + 1
    Me.NextScan = DateAdd("n", Me.IntervalBox.Value, Now)

    Form2.ScanCountLabel.Text = Me.ScanCount
    Form2.NextScanLabel.Text = Me.NextScan
    Form2.CurrentActionLabel.Text = "Waiting..."

    'Increment next file index and update in config file
    Me.FileIndexBox.Value = Me.CurrFileIndex
    SaveCfg()

End Sub

Please be indulgent with me, I am aware that the code is probably a nightmare for programming pros with lots of bad stuff, but it is literally my first VB program, and I am eager to learn.

So basically, the rest of the program is a form where I enter the target directory for the scan, the filenames, resolution etc, and when I click on 'start scanning', it - runs scannerloop one first time - starts a 'scantimer' which launches scannerloop each time it ticks.

As I said, it works perfectly with 1 scanner (files created as expected, logfile updated, etc) but as soon as I have 2 scanners, only the first scan works and then, when scanner#1 is supposed to start scanning, it doesn't and the led of scanner#2 starts blinking (as if it was scanning, but it's not scanning)

I hope someone will be able to help me.

Thanks in advance.

Vince

UPDATE - thing that I tried which may be of interest : I just tried to add a for loop to make it scan from both scanners several times (so, independantly from the timer and the rest of the program basically) :

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 :

 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 :

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

and here is the logfile generated :

Scan starts 29/11/2012 9:24:31 AM | Interval :Start scanning with 5 min | Res:100 DPI | 
29/11/2012 9:24:31 AM | Scanner #1 | Img initialized
29/11/2012 9:24:31 AM | Scanner #1 | properties initialized
29/11/2012 9:24:49 AM | Scanner #1 |Transfer done
29/11/2012 9:24:49 AM | Scanner #1 | saved C:\__2\scans\Scanner1\S1_img_1.TIF
29/11/2012 9:24:49 AM | Scanner #1 | Scanned C:\__2\scans\Scanner1\S1_img_1.TIF | duration: 18
29/11/2012 9:24:49 AM | Scanner #2 | Img initialized
29/11/2012 9:24:49 AM | Scanner #2 | properties initialized
29/11/2012 9:25:08 AM | Scanner #2 |Transfer done
29/11/2012 9:25:08 AM | Scanner #2 | saved C:\__2\scans\Scanner2\S2_img_1.TIF
29/11/2012 9:25:08 AM | Scanner #2 | Scanned C:\__2\scans\Scanner2\S2_img_1.TIF | duration: 19
29/11/2012 9:25:08 AM | Scanner #1 | Img initialized
29/11/2012 9:25:08 AM | Scanner #1 | properties initialized

it appears that things go wrong at this line :

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

I am not sure but maybe is better to post your code in codereview.stackexchange.com — Nianios

muhannad muhannad · Accepted Answer · 2014-02-05T22:37:37

this code for scanning image :"dont forget adding wiaaut.DLL from windows\sys32 to solution ref." first check if scanner device is attached

Dim tempfile As String
Dim mydevice As WIA.Device
Dim item As WIA.Item
Dim imfile As WIA.ImageFile
Dim Commondialog1 As WIA.CommonDialog
sub check()
  On Error Resume Next
    Commondialog1 = New WIA.CommonDialog
    mydevice = Commondialog1.ShowSelectDevice
    MsgBox(mydevice.Type)

  On Error GoTo Err_btnTakePicture_click

end sub
'then connect to scanner

sub scan()
    'put the path and name for the location of your temp file here.
    tempfile = ("d:\filename.jpg")

    'the next 4 lines deletes the old temp file if it exists
    Dim filesystemobject = CreateObject("Scripting.FileSystemObject")
    If filesystemobject.fileExists(tempfile) Then
        Kill(tempfile)
    End If

    'the next two lines set up the configuration
    Dim Commondialog1 As New WIA.CommonDialog
    mydevice = Commondialog1.ShowSelectDevice

    Dim wiaFormatJPEG As String = "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}"

    item = mydevice.Items(1)


    imfile = DirectCast(Commondialog1.ShowTransfer(item, wiaFormatJPEG, False), WIA.ImageFile)

    'this line saves the picture to a specified file
    imfile.SaveFile(tempfile)


    MsgBox("Picture taken")
    PictureBox1.ImageLocation = tempfile

  Exit_btnTakePicture_click:
    mydevice = Nothing
    item = Nothing
    Exit Sub

  Err_btnTakePicture_click:
    MsgBox(Err.Description, vbOKOnly + vbCritical, "Error Taking Picture")
    Resume Exit_btnTakePicture_click
   end sub

Automate scanning from multiple scanners on the same computer using WIA and VB

1 Answers