AOPU specializes in providing professional multi door access control systems. AOPU products are geared to all needs, from the office buildings, housing estates to multiple-site high tech corporations, universities, banks, police stations and prisions etc. Our products include: RS485 network single-door access controller, RS485 network multi-door (2 doors and 4 doors) access controller; TCP/IP network single-door access controller, TCP/IP network multi-door (2 doors and 4 doors) access controller; Access control software; Access control and time attendance administration system; RS485/232 access control converter; RF IC and ID card reader etc.