K8055 . time delay (input)

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1

We work with the interfaceboard K8055 under Windows XP (USB 2) and Visual Basic.net from Visual Studio 2005 . We need fast input answer (20 ms) ; the first routine with timer1 runs fast enough, but the second one with timer2 is too slow (250 ms). Could anybody explain the difference between these routines?
We need the second version for our applications.

This is our source-code:

[color=#0000FF]Public Class Form1

Private Declare Function OpenDevice Lib "k8055d.dll" (ByVal CardAddressChannel As Integer) As Integer
Private Declare Sub CloseDevice Lib "k8055d.dll" ()
Private Declare Sub WriteAllDigital Lib "k8055d.dll" (ByVal Data As Integer)
Private Declare Function ReadAllDigital Lib "k8055d.dll" () As Integer[/color]
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub

Private Sub Connector_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Connector.Click
    OpenDevice(0)
End Sub

Private Sub Disconnector_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Disconnector.Click
    CloseDevice()
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Timer1.Start() : Timer2.Stop()
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    WriteAllDigital(ReadAllDigital)
    Label1.Text = ReadAllDigital
End Sub

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
    Dim K As Integer
    K = ReadAllDigital
    WriteAllDigital(K)
    Label1.Text = K
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    Timer2.Start() : Timer1.Stop()
End Sub

End Class

2

It seems that there is only 20ms delay if the program is run with USB1.1.

This is the code I run:

Dim i As Integer Dim K As Integer For i = 1 To 2000 K = ReadAllDigital WriteAllDigital(K) Next
USB1.1
The blue trace indicates the digital input and the red one digital output.

USB2.0