CODE --> C#

<asp:UpdatePanel ID="MachineUpdate" runat="server" UpdateMode="Conditional">
        <ContentTemplate>

            <div id="MachineName" style="">

                <uc1:MachineNameControl runat="server" ID="MachineNameControl" commandValue="" />

            </div>

        </ContentTemplate>
</asp:UpdatePanel>

My code in MachineNameControl (ascx file)
  public partial class MachineNameControl : System.Web.UI.UserControl
    {

        public String commandValue { get; set; }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!String.IsNullOrEmpty(commandValue))
            {

                this.MachineNameDataSource.WhereParameters.Clear();
                this.MachineNameDataSource.AutoGenerateWhereClause = false;
                this.MachineNameDataSource.Where = "it.Head_Id = " +  Convert.ToInt32(commandValue) + " ";
            }
            else
            {
                this.MachineNameDataSource.WhereParameters.Clear();
                this.MachineNameDataSource.AutoGenerateWhereClause = false;
                this.MachineNameDataSource.Where = "it.Head_Id > 0  ";
            }
        }
}
My Problem in client side (I've tried to change attribute value of usercontrol and refresh the updatepanel, result is still same and nothing happended)

            $(function () {

                $("#<%= MachineNameControl.ClientID %>").attr("commandValue", "2");

                __doPostBack('<%= MachineUpdate.ClientID %>');

           }