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Multiprotocol I/O Modules Modbus User Manual


The MINI, MIX, and MAX series of multiprotocol I/O modules with RS485 and IP 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/Os in building automation. Depending on the version, the modules are equipped with a mix of different types of I/O in one unit:

  • MINI series: 4 or 8 inputs and outputs;
  • MIX series: 18 or 38 inputs and outputs;
  • MAX series: 24 or 12 inputs or outputs.

All I/O modules have BTL, and MINI/MIX series–UL, certificates. The modules with RS485 and IP are factory-equipped with the two most popular open communication protocols: Modbus (RTU, ASCII, 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 TCP/IP to Modbus ASCII/RTU gateway 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. These versatile devices will fit any BMS perfectly.

The MIX38-IP (MIX series), 4TO-H-IP (MINI series), and 24I-IP (MAX series) modules

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

Revision History

1.1010 Nov 2023
  • DHCP functionality added (MINI/MIX modules)
  • Modbus TCP free sockets counter functionality added (MINI/MIX modules)
1.915 Feb 2023
  • New title of the user manual for all series of modules (MINI/MIX/MAX) - Multiprotocol I/O Modules User Manual;
  • MAX series of I/O modules added
  • DHCP functionality added (MAX modules)
  • Modbus TCP free sockets counter functionality added (MAX modules)
1.825 May 2022Rebranded
1.713 Oct 2020
  • 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.
1.619 Feb 2020
  • New temperature sensors implemented in Celsius and Fahrenheit degrees
  • New Modbus function 0x17 Read/Write Multiple registers
  • New Modbus function 0x2B to read the VENDOR_NAME,MODEL_NAME, FW_VERSION, HOMEPAGE
  • Supporting Modbus address 0xFF for communication with the gateway (IP module)
  • Improved filtering on UI
  • Fixed one record in sensor 30k6A1 table –resistance 60713 to 80713 (5°C)
1.55 Oct 2018
  • Corrections of typing errors in the text
  • Added imperial unit of measure
1.47 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
1.316 May 2017
  • Hardware Version information on the main tab on the web page and in the Modbus register added
  • new action in Modbus register no 0 – enter the bootloader
  • RS485 biasing control added for MINI IP modules with hardware version >= 2.0
  • www page: RS485 Biasing Resistors activating option (appears only in MINI modules with hardware >= 2.0)
  • modules names on web page corrected (added -H for all modules with hand operation switches)
1.23 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 for 4I4O added: 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 added 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 detecting short circuit and disconnection, regardless of filter settings on universal inputs;
  • Fixed bug with Stop bits, it was always 1.
1.11 Feb 2016
  • Information about the capacitive load relay added to the technical specifications.
  • Information about load Triac Outputs added to the technical specifications.
  • Description of the new MINI module 4x Triac Outputs: 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 (it used to start counting from the rising edge).
  • New gateway functionality blocking Send Modbus Error.
  • Tables with PT1000 and NI1000 updated with more accurate data with new FW measuring resistance at these sensors with the accuracy of 0.1 Ω.
1.028 Aug 2015First edition
Revision history

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