The Card Reader Interface Board or 2-Door Controller is connected via the encrypted OSDP bus to the S1000 Controller. Each of the 2 OSDP buses can connect up to 16 devices, making a total of 32 Card Reader Interface Boards that can be connected to the S1000. If each of the 32 Card Reader Interface Boards supports 2 doors, then a maximum of 64 doors can be accommodated - this can be 32 doors with read IN and read OUT or 64 doors with read IN and egress OUT