CD-108 connects to eight (8) Emergency Call units.  This allows a maximum of 64 residents per rack and up to 16 racks per system, giving the system a maximum capacity of 1024 residents

All CD-108 cards are interchangeable however; the DIP switch must be set correctly in order for the card to work properly.  Each board is numbered 0 through 8 and both the board number and rack number must be set.  The CD-108 that is addressed as board zero (0) must be installed in the Master card slot located in the last slot furthest from the CDPS-3 power supply. 

CD-108 Switch settings: 

On each CD-108 card there is a DIP switch located on the rear of the board.  The switches are numbered 1 through 8.   Switches 1 through 3 are set to the card address and switches 4 through 7 set the Rack address.  Switch settings are all set in binary format.