this barcode scanner will show
  KD-R411ED 105X0001 inside one
  textfield...i want it become KD-R411ED
  in first text field and 105X0001 in
  other textfield...all automatically
  separate into two textfield after scan
  the barcode... but for actually it
  appear in one textfield...this program
  is under progress...
you can do this...
var barCode = 'KD-R411ED 105X0001';
var data = barCode.split(" ");
you can access data this way...
var product = data[0]; // output KD-R411ED
var serial = data[1]; // output 105X0001
edit
your code:
<script type="text/javascript"> 
     function addtext() { 
       var barCode = this.(text); 
       $("#model").change(function() { 
           barCode = $this.val(); 
           var data = barCode.split(""); 
           $("#model").val(data[0]); 
           $("#serial").val(data[1]); 
       }); 
     }; 
</script>
try this:
 <script type="text/javascript"> 
    $(document).ready(function(){
       $("#model").change(function() {  
           var data = $(this).val().split(" "); // not the space in .split(" ")
           $("#model").val(data[0]); 
           $("#serial").val(data[1]); 
       });
     });
 </script>