Question

Basically I’m simply trying to implement a timer control that will swap banners for me and then update in an update panel. However the timer only affects my page once, and appears to be firing twice(I put a label on the form and attempted to increment by one each time it would update, and it jumped to 2 then stopped).

                   <asp:ContentPlaceHolder ID="cphHead" runat="server">


                    <asp:ScriptManager ID="ScriptManager1" runat="server">
                    </asp:ScriptManager>
                    <asp:Timer ID="Timer1" runat="server" Interval="6000" OnTick="Timer1_Tick">
                    </asp:Timer>
                    <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
                        <Triggers>
                            <asp:AsyncPostBackTrigger ControlID="Timer1" />
                        </Triggers>
                        <ContentTemplate>
                            <asp:Image ID="Image1" runat="server" ImageUrl="~/images/banner_2.jpg" />

                            <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
                        </ContentTemplate>
                    </asp:UpdatePanel>


                </asp:ContentPlaceHolder>

and there is my code behind

Partial Class ASPTravel
    Inherits System.Web.UI.MasterPage

    Private intnum As Integer = 0
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load


    End Sub



    Protected Sub LoginStatus1_LoggingOut(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.LoginCancelEventArgs) Handles LoginStatus1.LoggingOut
        Session.Abandon()
    End Sub




    Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick

            intnum = intnum + 1
            Label1.Text = CStr(intnum)
            ' If intnum = 0 Then
            '  Image1.ImageUrl = "~/images/banner_1.jpg"
            '  intnum = 1
            ' Else
            '  Image1.ImageUrl = "~/images/banner_2.jpg"
            'End If
            Dim n As Integer = New Random().Next(1, 2)
            Image1.ImageUrl = "~/images/banner_" + n.ToString() + ".jpg"



    End Sub
End Class

Answer 1

Remove the Handles Timer1.Tick from your code behind and it will works fine.I have checked it.
like this.

 Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs)

Reference: http://forums.asp.net/t/1642896.aspx/1

also user viewstate instead of variables. Variables are initialized on every postback in asp.net. So instead of saving value in a variable Private intnum As Integer = 0 save it in a View state like this

ViewState["intnum"] = 0

and in your timer click event.

ViewState["intnum"]= (int) ViewState["intnum"] + 1
Label1.Text = CStr(ViewState["intnum"])