Each GPIO-16 interface provides 16 opto-isolated inputs and 16 relay outputs. The GPI inputs can be set up to remotely controlled keypanel keys to activate intercom ports, party lines, relay outputs, etc. within the intercom system. The relay outputs are typically assigned for activation from keypanel keys. They can be used to control lighting or to key remote transmitters, paging systems, etc. Relays can be assigned to keys via the AZedit intercom configuration software. The GPIO-16 supports two communication modes: RS-485 serial and Ethernet. The UPL logic in AZedit enables custom functionality that automates or schedules certain actions to occur.