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November 28th, 2012, 12:51 AM
#1
Trouble automating scanning using WIA and VB.NET
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 paste the rest as it is the UI and folder management)
Code:
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.
I do not want any dialog to appear to as me which scanner to select or which parameters to use as this program is supposed to run over several weeks in order to scan hundreds of images without anyone to attend it.
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
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