Aiphone - AX-320C 3Central Exchange Unit for 32 Door StationsAdd on exchange unit for 32 AX Series door or sub stations. Features Wiring hub for AX Series system using Cat 5e Two 24V DC power supply input terminals Rack mountable Specs Door Release Programmable dry contact, 24V AC DC 500mA (use RY 24L for larger contact rating) Mounting 19" EIA rack (2U) or wall mount Wire Type Between Door Sub Station and Add On Exchange Unit: Cat 5e Power Supply to Central Exchange Unit and Add On Central Exchange Unit: 2