Frequently asked questions and deal with access control systems Symptom 1: access control device after a good connection with the software testing can not communicate with the computer. When using RS422 communication possible reasons: (1) the wiring between the controller and the network expansion is incorrect. (2) on the controller jumper is closed (communication for RS232); distance (3) controller to the network expansion over the effective length (1200M); Serial (4) computer is normal, with or without normal join or occupied by other programs installed monitoring system, and then test to exclude these reasons; (5) the software settings, the device address number actually set, coupling does not correspond; (6) cell line interference monitoring system installed, you can not communicate normally. Frequently asked questions and deal with access control systems Symptom 5: The effective card near the reader, the buzzer sounds, LED light turns green, but the door did not open. Possible causes: (1) the connection between the controller and electric control lock is incorrect; (2) to the power locks power supply is normal (power locks require a separate power supply); (3) electric lock failure; (4 ) bolt and locking occurs mechanically stuck; Symptom 6: A valid card near the reader, the buzzer sounds for companies to install monitoring systems, door open, but the reader light off. Possible causes: (1) controller and electric locks share a power supply, reverse power locks work when potential interference, causing the controller to reset; (2) Power is not enough, resulting in the controller, the reader does not work. Install monitoring systems _ source maintenance (certified) _ install monitoring systems provided by Zhengzhou source maintenance Electronic Technology Co., Zhengzhou source maintenance Electronic Technology Co., Ltd. (www.hnxywb.com) is a leader in Zhengzhou, integrated monitoring system, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. In leading source maintenance staff warmly welcome all inquiries negotiations to create a better source of future maintenance.