VintaSoft Twain .NET SDK v10.2
In This Topic
    How to detect that paper is jammed?
    In This Topic

    Kodak scanner can send asynchronous event when paper is jammed, scanner is switched off, etc.
    TWAIN Advanced Demo shows how to work with asynchronous events of device.


    Example: Here is an example that shows how to detect when paper is jammed.

    ''' <summary>
    ''' Detects the paper jamm.
    ''' </summary>
    Public Sub DetectPaperJam(ByVal device As Device)
        ' disable device UI
        device.ShowUI = False
        ' disable device when images are acquired
        device.DisableAfterAcquire = True
    
        ' open the device
        device.Open()
    
        ' set device settings
        device.PixelType = PixelType.RGB
        device.UnitOfMeasure = UnitOfMeasure.Inches
        device.Resolution = New Resolution(300.0F, 300.0F)
    
        Try
            ' get events supported by device
            Dim supportedDeviceEvents As DeviceEventId() = device.GetSupportedAsyncEvents()
            ' for each supported event
            For i As Integer = 0 To supportedDeviceEvents.Length - 1
                ' if device can report when paper is jammed
                If supportedDeviceEvents(i) = DeviceEventId.PaperJam Then
                    ' specify that device must report when paper is jammed
                    device.AsyncEvents = New DeviceEventId() {DeviceEventId.PaperJam}
    
                    ' subscribe to the device event
                    AddHandler device.AsyncEvent, New EventHandler(Of DeviceAsyncEventArgs)(AddressOf device_DeviceEvent)
    
                    Exit For
                End If
            Next
        Catch ex As Exception
            Console.WriteLine(ex.ToString())
        End Try
    
        ' subscribe to the Device.ImageAcquired, Device.ScanCompleted, ... events
        '...
    
        ' acquire images from device
        device.Acquire()
    End Sub
    
    ''' <summary>
    ''' Occurred the device event.
    ''' </summary>
    Private Sub device_DeviceEvent(ByVal sender As Object, ByVal e As DeviceAsyncEventArgs)
        Console.WriteLine("Paper is jammed.")
    End Sub
                  
    
    /// <summary>
    /// Detects the paper jamm.
    /// </summary>
    public void DetectPaperJam(Device device)
    {
        // disable device UI
        device.ShowUI = false;
        // disable device when images are acquired
        device.DisableAfterAcquire = true;
    
        // open the device
        device.Open();
    
        // set device settings
        device.PixelType = PixelType.RGB;
        device.UnitOfMeasure = UnitOfMeasure.Inches;
        device.Resolution = new Resolution(300f, 300f);
    
        try
        {
            // get events supported by device
            DeviceEventId[] supportedDeviceEvents = device.GetSupportedAsyncEvents();
            // for each supported event
            for (int i = 0; i < supportedDeviceEvents.Length; i++)
            {
                // if device can report when paper is jammed
                if (supportedDeviceEvents[i] == DeviceEventId.PaperJam)
                {
                    // specify that device must report when paper is jammed
                    device.AsyncEvents = new DeviceEventId[] { DeviceEventId.PaperJam };
    
                    // subscribe to the device event
                    device.AsyncEvent += new EventHandler(device_DeviceEvent);
    
                    break;
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
    
        // subscribe to the Device.ImageAcquired, Device.ScanCompleted, ... events
        //...
    
        // acquire images from device
        device.Acquire();
    }
    
    /// <summary>
    /// Occurred the device event.
    /// </summary>
    private void device_DeviceEvent(object sender, DeviceAsyncEventArgs e)
    {
        Console.WriteLine("Paper is jammed.");
    }