AC20
The freely programmable micro DCS
To develop complex controls (multiloop, cascate, override,   ...) with flexibility and 
simplicity in programming
   - Up to 8 analog input and 8 analog output
   - Up to 32 digital input and 32 digital output (with expansion units)
   - Serial communication RS485 Modbus RTU
   - Arcnet LAN for high speed communications among AC Stations
   - Several control strategies and wide library of function blocks available for   
     programming

AC30
Controller/Programmer for continuous and discontinuous processes
The programmable multiloop with Real Time Clock and   Programmer to manage 
synchronized controls and sequences 
   - Up to 8 analog input and 8 analog output
   - Up to 32 digital input and 32 digital output (with expansion units)
   - Up to 64 fully configurable and selectable programs, 400 segments maximum
   - Real time clock for weekly event
   - Serial communication RS485 Modbus RTU
   - Arcnet LAN for high speed communications among AC Stations
   - Several control strategies and wide library of function blocks available for   
programming