Skip to main content
Skip table of contents

iSMA-B-MINI/MIX BACnet User Manual


The MINI and MIX series of I/O modules with RS485 and IP (2 Ethernet) have been designed for building distributed control systems using MAC36, AAC20, or another controller. Each module is equipped with the most commonly used types of I/O in building automation. Depending on the version, the device has 18 or 38 inputs and outputs, a mix of all types of I/O in one unit. All I/O modules have BTL and UL certificates.
The modules with RS485 and IP (2 Ethernet) are factory-equipped with the two most popular open communication protocols: Modbus (ASCII, RTU, TCP/IP) and BACnet (MS/TP, IP), which are selected using DIP switches. Rotary switches are used to set the module address, which facilitates and accelerates the process of commissioning the system. Built-in mini USB allows for the initial configuration of the unit without external power supply.
Built-in Modbus gateway TCP/IP to Modbus ASCII/RTU enables to connect additional modules/devices that communicate via Modbus RS485.
Thanks to supporting open communication standards I/O modules can be installed in both new and completed installations, as part of existing BMS. This versatile device will fit any BMS perfectly.

The MINI and MIX IO modules

This user manual outlines all information specific to using I/O modules in the BACnet protocol.

Revision History





28 Aug 2015

First edition


1 Feb 2016

  • Information about the capacitive load relay added to the technical specifications.

  • Information about load triac outputs added to the technical specifications.

  • Information about COV added.

  • New BACnet objects UP_TIME and WATCHDOG. 

  • Universal Inputs: COV support and new feature of flag OUT_OF_SERVICE added.

  • Universal Inputs: new objects added: UI_CONFIGRATION, UI_RESOLUTION, UI_FILTER and UI_DRY CONTACT.

  • Digital Inputs: COV support and new feature of flag OUT_OF_SERVICE added.

  • Digital Inputs: new objects added: BIA_COUNTER, and BI_COUNTER.

  • Analog Outputs: COV support and new feature of flags OUT_OF_SERVICE and STATUS_FLAG added.

  • Analog Outputs: new objects added: AO_CONFIGURATION, AO_HAND_STATUS, and AO_HAND_VALUE.

  • Digital Outputs: COV support and new feature of flag OUT_OF_SERVICE and STATUS_FLAG added.

  • Digital Outputs: new object added:HAND_STATUS. 

  • Description of the new MINI module 4x Triac Outputs added: 4TO-H and 4TO-H-IP. 

  • MINI - 4I40-H and 4I40-H-IP module built-in application: Change of logic in the Time relay mode. Now the timer counts from the falling edge (is used to do it from the rising edge).

  • MINI - 4I40-H and 4I40-H-IP Module built-in application: new objects added MODE_TIME, COMMAND, and BLOCKING.

  • Shortlist of BACnet objects added.

  • Tables with PT1000 and NI1000 updated with more accurate data, due to new FW measuring the temperature at these sensors with 0.1°C accuracy.


4 Jan 2017

  • New HVAC functions Heating and Cooling in 4U4O based on output thermostatic control with a setpoint and differential value setting;

  • New input mode added for 4I4O: Time Relay NC [ms], Time Relay NO and NC in seconds, Input Forwarding;

  • New input mode added for 4U4O: Ordinary IO, Monostable Relay, Bistable Relay, Time Relay NO and NC [ms], Time Relay NO and NC in seconds, Input Forwarding, Heating, Cooling with corresponding BACnet objects and Modbus registers;

  • Output for resetting to default after input mode change in 4U4O and 4I4O;

  • Improved BACnet COV Increment now can have values with the resolution of 0.1;

  • BACnet COV Increment access (read/write) through USB added;

  • Power Led added, flashing when the I/O watchdog is triggered;

  • I/O watchdog reset after read/write registers through USB modified;

  • Sensors added for the immediate detection of short circuit and disconnection, regardless of filter settings on universal inputs;

  • Fixed bug with Stop bits, it was always 1.


16 May 2017

  • Hardware Version info added on the main tab on the web page and in the Modbus register

  • new action in the Modbus register no 0 – enter the bootloader

  • RS485 biasing control added for MINI IP modules with hardware version >= 2.0

  • new Device Object properties added: Version type, Baud rate, User Baud rate, IP address, Subnet mask, Default Gateway, HTTP port, and UDP port

  • www page: RS485 Biasing Resistors activating option (appears only in MINI modules with hardware >= 2.0)

  • www page fixed: COV increment always in a format with one decimal place

  • module names on the web page the corrected (added -H for all modules with hand operation switches)


7 Dec 2017

  • Firmware Version 6.0 released with BACnet certification

  • fixed out of service flags in AO, BO and TO

  • fixed overridden flags in AO, BO and TO

  • fixed bug with number of counters for Binary input object (now variable is 32 bit)

  • changed AO-1, BO-1, TO-1 HAND_STATUS Access to read-only

  • changed resistance table for 2.2K3A1 sensor


5 Oct 2018

  • Corrections of typing errors in the text

  • Added imperial unit of measure

  • MINI and MIX modules earned UL recognized component mark


19 Feb 2020

  • New temperature sensors implemented in Celsius and Fahrenheit degrees

  • Improved filtering on UI

  • Device Name (Object Name) in BACnet is saved in EEPROM memory

  • Fixed one record in sensor 30k6A1 table –resistance 60713 to 80713 (5°C)

  • “Send I Am” message is not sent if BACnet is turned off


13 Oct 2020

  • Improved functionality of the BBMD: new default IP address, registering to the BBMD server is disabled if the BBMD IP address is left default;

  • Introduced an option to disable web server access by changing the HTTP port to 0;

  • Corrected summary table for all modules;

  • Updated information about biasing resistors in MIX modules;

  • General improvements and bugfixes.


25 May 2022


Revision history

JavaScript errors detected

Please note, these errors can depend on your browser setup.

If this problem persists, please contact our support.