jQuery Grid Plugin - jqGrid

Hello, I used Grid for edditing database record. All features working properly. I would ask anyone does is able sent in post parameter  additional column value not editable in grid.?

I tried set post parameter in onSelectRow function. Alert show coorect value from column device. But post parameter not set after enter. Only id and edit_value columns (edit_value has editable:true)

var ret,device;

            onSelectRow: function(id){
                if(id && id!==lastsel){
                    jQuery('#list1').restoreRow(lastsel);
                    jQuery('#list1').editRow(id,true);
                    lastsel=id;
                }
                ret = jQuery("#list1").getRowData(id);
                device = ret.device;
                jQuery("#list1").setPostData({q:1,param1:device});

        }

thank you for any idea

Anton