The reasons for the failure are as follows: First, check whether the controller is set up anti-stealth, interlock, emergency door and other advanced functions, please cancel those Settings, and then make a judgment:  ① The connection between the card reader and the controller is incorrect or exceeds the effective length (120 meters); The connection between the controller and the card reader is incorrect, and the data0 and data1 signal cables of the card reader and the data0 and data1 cables of the controller are not connected one by one. ④ The line is seriously interfered with, and the card reader data cannot be transmitted to the controller ⑤ the card reader is faulty; ⑥ The controller is faulty.