The iSMA-B-AAC20 comes equipped with a built-in RS485, which can be used to expand the number of I/O by connecting iSMA MINI or MIX series I/O modules using Modbus ASCII/RTU. Additionally, the controller is extremely versatile, it has the ability to support numerous open communication protocols such as: BACnet, Modbus, SOX, DALI, M-Bus, 1-wire or oBIX (optional).
The AAC20 is mounted in a housing adapted for DIN rail mounting or directly on a panel, with separate, easy to remove connectors to allow for quick wiring without removing the entire module.


All universal inputs are equipped with 16-bit converters, which support the following types of inputs:

  • Temperature input support the following types of sensors: 10K3A1, 10K4A1, Carel 10K, 20K6A1, 2.2K3A1, 3K3A1, 30K6A1, SIE1, TAC1, SAT1, Pt1000, Ni1000

For sensor Pt1000 and Ni1000 use only 16-bit resolution

  • Voltage input 0-10 V DC | Input resistance 100 kΩ accuracy ±0,1% measurement resolution 3 mV @ 12-bit and 1 mV @ 16-bit
  • Current input 0-20 mA (external resistor 499 Ω required)
  • Resistive input 0-1000 kΩ: measurement resolution for 20 kΩ load 20 Ω @ 12-bit and 1 Ω @ 16-bit
  • Dry contact input

  • Inputs potential-free (dry contact)
  • Fast pulse counter up to 100 Hz writing to the EEPROM

All analog outputs feature 12-bit ADC which provides a resolution of 10 mV and error of ± 0.5%. Supports the following types of outputs:

    • Output Voltage 0-10 V DC max. 20 mA (AO6- max. 5 mA)
    • PWM output | 0.01 Hz, 0.1 Hz, 1 Hz, 10 Hz, 100 Hz

AO5 and AO6 can only be use if 1-Wire port is not in use, please notice for AO6 maximum current load is up to 5 mA

  • The relay outputs (NO) max. 3A, 230 V AC / 30 V DC


  • ARM Cortex-M4 204MHz
  • ARM Cortex-M0 204MHz

  • RS485 half duplex
  • Baud rate 2400 to 115200 bps
  • 2xEthernet with built-in switch
  • 1-Wire interface
  • Micro SD card slot
  • USB Host
  • protocols: Modbus, BACnet, 1-wire, oBIX (optional)

    • 24 V AC / DC

  • Dimensions: 106x110x62 mm.
  • Construction: plastic, self-extinguishing (PC / ABS)
  • Mounting DIN (DIN EN 50022 standard)
  • Cooling: internal air circulation

  • Operating temperature: -10 ° C to 50 ° C
  • Storage temperature: -40 ° C to 85 ° C
  • Relative humidity: 5 to 95%, non-condensing
  • Degree of protection: IP40 – for indoor installation