The access control expansion module communicates with the access control terminal or door station through the RS-485 BUS and connects with the door detector, exit button, card reader and lock. It can transmit card information, door opening information and alarms to the access control terminal or door station, improving the security of access control. - Used to expand access control functions by cooperating with the access control terminal and door station. - Supports RS-485 communication. - Can be connected to electronic or magnetic locks to enhance security. - Provides 3 indicators to show whether the device is on or off, function and the status of the door.