门禁故障现象（Access control failure phenomenon）.doc

门禁故障现象（Access control failure phenomenon） Common faults and elimination of access control system Malfunction 1 One machine is out of communication Possible causes: For the specific number of access control, first disconnect the communication line and measure the voltage of the entrance guard communication line A and B, the value is about 2.3V, otherwise the communication chip may be a problem; Check the communication bus A, B terminal voltage, there is no 5V or so, if not, then the other access control on the bus access problems, you need to check one by one. Malfunction 2 Access control light does not flash or buzzer interrupted alarm Possible causes: Check the power supply voltage below 9V, the voltage may be too low Check whether a short circuit or circuit board components. Malfunction 3 No response to reading card Possible causes: May be the work of the microcontroller is not normal, need to restart The card is incorrect Malfunction 4 Close the card to the reader, the buzzer doesnt turn off, the indicator doesnt respond. Possible causes: Check the card for damage Check whether the supply voltage is normal Change the card reader again Malfunction 5 485, network controller can not communicate with the computer properly Possible causes: Check the power converter is connected to the 485 signal; Xian Zheng, check whether the reverse negative converter; check the serial port of the computer is normal, there is no normal connection or by other program, close other programs or replace the serial port or host; Check that the software settings are correct; Is the serial number of the controller added correctly: check whether the product serial number in the controller settings of the controller is labeled with the silver on the controller board S/N: On the two five digit. The distance from the controller to the 485 converter exceeds the effective length 1200M; The communications line is for UTP or communication lines, whether the structure mode: hand in hand or line inter