How to change attributes value of user control in div

 ID="MachineUpdate" runat="server" UpdateMode="Conditional"> 
       
          id="MachineName" style=""> 
              runat="server" ID="MachineNameControl" commandValue="" /> 
         

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 %>');            
      }
Based on the coding in above, I've tried to change attributes value of '<%= MachineNameControl.ClientID %>' and refresh the content in updatepanel by calling __doPostBack('<%= MachineUpdate.ClientID %>'). Result is same and nothing change to filter record? Can anyone give me a guide, please.Thank!!