public function __construct()
 {
     if (!self::$PDOInstance) {
         try {
             $parametros = array();
             if (DB_MANAGER == "mysql") {
                 $parametros = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES ' . DB_CHAR);
             } else {
                 $parametros = array();
             }
             if (DB_MANAGER == "sqlsrv") {
                 self::$PDOInstance = new PDO(DB_MANAGER . ":Server=" . DB_HOST . ";", DB_USER, DB_PASS, $parametros);
             } else {
                 self::$PDOInstance = new PDO(DB_MANAGER . ":host=" . DB_HOST . ";dbname=" . DB_NAME, DB_USER, DB_PASS, $parametros);
             }
         } catch (PDOException $e) {
             Logs::procesa($e);
         }
     }
     return self::$PDOInstance;
 }