使用USB条形码扫描仪读取条形码,同时忽略键盘数据输入,而扫描仪产品ID和供应商ID未知

Question

有没有办法从USB条形码阅读器读取而忽略键盘而不知道USB扫描仪的PID或VID？我知道有一种方法可以通过使用USB扫描仪的VID和/或PID来区分USB扫描仪输入和键盘输入; 这是使用http://nicholas.piasecki.name/blog/2009/02/distinguishing-barcode-scanners-from-the-keyboard-in-winforms/中的代码完成的. 但是有另一种解决方案来区分键盘和USB扫描仪不将扫描仪的VID或PID放在配置文件(或源代码)中？不想在配置文件中放置各种VID或PID的原因是,正在开发的应用程序将部署在多台笔记本电脑上,并且附加了任意类型的扫描仪.

此外,我不想配置扫描仪的输出开始和结束序列,因为扫描仪也被同一台机器上的其他软件使用,我不想更改代码在其他软件上.出于与前面提到的相同的原因,我不想将条形码阅读器编程为串行模式.

Answer 1

有一种方法可以区分键盘和USB条形码阅读器

你可以依赖这些事实:

1. 条形码阅读器以最少4个字符扫描的代码
2. 条形码阅读器扫描的代码以RETURN"ENTER"结束
3. 扫描孔条形码需要不到50毫秒

这是一个使用VS2005 VB的简单表格包含:

1. TextBox1的
2. TextBox2中
3. textbox3
4. Button1的
5. Timer1"时间间隔设置为50"ms"

Public Class Form1

Dim BarcodeStr As String = ""
Dim IsBarcodeTaken As Boolean = False
Dim Str As String = ""
Dim str3 As String = ""


Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

    If Timer1.Enabled = False Then
        Str = TextBox1.Text
        str3 = TextBox3.Text
    End If

End Sub

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
    If Timer1.Enabled = False Then
        Timer1.Enabled = True
    End If


    BarcodeStr = BarcodeStr & e.KeyChar
    If Asc(e.KeyChar) = 13 And Len(BarcodeStr) >= 4 Then
        IsBarcodeTaken = True
        TextBox2.Text = BarcodeStr


    End If

End Sub
Private Sub Form1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyUp
    If IsBarcodeTaken = True Then
        TextBox1.Text = Str
        TextBox1.Select(Len(TextBox1.Text), 0)
        Str = ""

        TextBox3.Text = str3
        TextBox3.Select(Len(TextBox3.Text), 0)
        str3 = ""
    End If

End Sub


Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    BarcodeStr = ""
    IsBarcodeTaken = False
    Timer1.Enabled = False
End Sub


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    TextBox2.Text = ""

End Sub

End Class