Model RTI16 RTO16 RTAD Points / Module 16 Points Digital Input 16 Points Digital Output 4 Point Analog Input, 2 Point Analog Output Digital Input Signal Dc. Voltage Source , active Low -- -- Digital Output Signal -- Transistor, Open Collector NPN Type -- Analog Input & Output Signal -- -- 0 to 10 Vdc. OR 4 to 20 mA. 8 Bit resolution Isolated Circuit Opto isolators Opto isolators Opto isolators Relay Output -- Option (RLY16) -- Communication RS232c/RS485 RS232c/RS485 RS232c/RS485 Maximum Module in the system 16 Module 16 Module 16 Module Fac-talk Protocol Yes Yes Yes Installation Rail rack Rail rack Rail rack Dimension (W*L*H) mm. 125*136*29 125*136*29 125*136*29 Power Supply 24 Vcd. , 1A. 24 Vdc. , 1A. 24 Vdc. , 1A.