Qbus QMI/Pro20 interface for HVAC integration

Up to 20 devices, ideal for commercial and project-based installations.
Preconfigured Modbus structure for smooth integration.
Fast configuration in System Manager III, without complex programming.
Compatible with Daikin, Mitsubishi, Fujitsu, among others, and many more.
Combination of Modbus RTU with TCP/IP devices.
Ability to create custom conversion tables and logic at the device level.
BACS compliant, future-proof for professional BMS systems.

Technical info

QMI/Pro20 is the smart solution for connecting HVAC devices and energy meters to your Qbus installation. Designed for commercial and project-based installations, with fast Modbus RTU and TCP/IP integration for up to 20 devices, clear, reliable, and without unnecessary complexity. Without replacement, we connect your existing HVAC assets and meters via QMI/Pro20 to an open, vendor-independent platform that makes your building BACS-ready today for data-driven monitoring and optimization.

Available from 01/06/2026.

Typical Use Cases

Intelligent Climate Control
Air conditioning that automatically adjusts based on temperature settings, occupancy, and schedules — always the right comfort without waste.

Smart Ventilation
Healthy air quality through demand-driven ventilation based on CO₂ levels and occupancy.

Efficient Heat Pump Control
Heating only when necessary, with optimal alignment to the heating demand and chosen operating regime.

Insights into Energy Consumption
Real-time monitoring via energy meters provides you with immediate control and valuable data for further optimization.

Integration with Existing BMS
Connection with third-party building management systems (BMS), where HVAC values and statuses are automatically forwarded to a central platform.

Technical info for installers

Functional Description
Module for integrating HVAC devices and energy meters with a Modbus RTU or Modbus TCP/IP interface into a Qbus installation for medium and larger projects.
The QMI/Pro20 acts as a Modbus master and allows up to 20 slave devices to be connected, with a total of up to 140 registers. This enables multiple air handling units and heat pumps to be centrally controlled and monitored within a single Qbus environment.
Through System Manager III, the correct Modbus parameters and registers for each device can be conveniently selected and configured. The QMI/Pro20 offers extensive settings options for:
Data format (16, 32, 64 bit and Float32/64)
Word order (Big endian, Little endian, Word swap)
Signed/unsigned configuration
Dynamic conversion tables
Custom conversion formulas
Default settings are automatically filled in when adding registers, enabling rapid and low-error integration, even in larger installations.
The communication settings (RTU or TCP/IP) are configurable depending on the application. With TCP/IP connection, each slave, IP address, and port can be individually set, with monitoring for duplicate IP addresses within the installation.
The QMI/Pro20 features additional reliability and diagnostic functions, including:
Communication status per slave device
Configurable write-retry mechanisms
Possibility for periodic re-sending of write values
Exclusion option per register
Additional Modbus commands are regularly integrated into the Qbus QMI Interface Module upon customers' request. Each QMI/Pro20 module has a unique serial number, enabling programming and identification at all times. All configured data is stored internally in permanent memory. Firmware updates are done via the Qbus bus.
Technical specifications
General Specifications
Power Supply: Qbus bus
Ambient Temperature: Operating Temperature: 10°C to 50°C Storage Temperature: -10°C to 60°C
Maximum Humidity: 93%, no moisture condensation
Bus Current:
no-load: 45 mA at nominal 18 V
RTU loaded: 50mA at nominal 18V
TCP loaded: 50mA at nominal 18V
RTU & TCP loaded: 80mA at nominal 18V
Max. Installation Height: 2,000 meters.
QMI/Pro20 Connections
The QMI/Basic acts as a Modbus master and supports both Modbus RTU (RS485) and Modbus TCP/IP
Up to 140 Modbus registers can be configured per module.
Up to 20 Modbus slave devices can be linked per module.
The number of registers required per external device (usually 5–8) determines the maximum number of effectively controllable devices within the limit of 140 registers.
The module supports extensive register configuration:
Data Format: 16-bit, 32-bit, 64-bit, Float32, Float64
Word Order: Big endian, Little endian, Word swap
Signed / Unsigned
Dynamic Conversion Tables
Custom Conversion Formulas
RS485 (RTU)
Maximum distance between QMI/Pro20 and external device: 1000 m
Cabling possible in bus (line) or star topology, according to RS485 guidelines
Configurable baud rate, parity, and stop bits via System Manager III
Ethernet (TCP/IP)
10/100 Mbps
DHCP for QMI, static IP to slave device
Individual IP configuration per slave device
Check for duplicate IP addresses within the same module
Standard Modbus TCP port 502 (customizable)
Diagnostic Functions
Communication status per slave device
Option for periodic re-transmission of write values
Option to exclude specific registers in re-transmission
Physical Specifications:
Housing: plastic, self-extinguishing according to UL94-V0
Protection Rating: IP20 in accordance with EN60529
Installation: quick installation on DIN-rail, width 2 modules
Dimensions (H x W x D): 62 mm x 90 mm x 36 mm
Weight: approximately 0.072 kg
Compliance:
CE conformity
Bus: 18 VDC low voltage
Non-toxic, compliant with WEEE/RoHS
Conforms to EN 60730-1:2000 +A11:2002
Sizing
Explanation of Symbols

Equipment where protection against the risk of electric contact is not only based on basic insulation but also on additional protection such as double insulation or reinforced insulation. There is no possibility for grounding.

Before connecting the device, it is mandatory to read the manual of the respective product. ISO7000-0434

Power supply connection (230V) to the power supply connector. IEC 60417-5036

CE conformity. All declarations of conformity are available upon request.
Warranty Provision

2 years from the date of delivery. The warranty becomes void if the module has been opened! The warranty period is extended by 2 years if it was installed by a certified Qbus installer.
In case of defects, Qbus support should be contacted by a certified installer. After registration with Qbus support, the defective module can be sent, unsealed and with a description of the defect, to our Qbus support.
QBUS N.V. Joseph Cardijnstraat 19, 9420 Erpe-Mere, Belgium
T +32 53 60 72 10 - F +32 53 60 72 19
Email: [email protected]

General

Safety regulations
Read the complete manual before installing and activating the module.
WARNING
Assembly, commissioning, and maintenance of the devices must be carried out by a certified electrician in accordance with the applicable legal requirements.
This device is intended solely for DIN rail mounting in accordance with EN50022. It must be mounted in a fire-resistant distribution board with ventilation openings.
Do not open the device. The warranty is void if the module is opened.
Risk of electric shock upon contact with live parts.

Install and wire

Installation

Click the module onto a DIN rail DIN EN50022.
Power Supply

The QMI/Pro20 is powered by the bus
Modbus cabling

RS485
The wiring between the Modbus port on the external device and the RS485 connector on the Qbus QMI interface must be done with solid conductors up to 0.8 mm². Use a CAT5 cable for this purpose. The green EIB cable can also be used for this (use the conductors individually).
TCP/IP
Connect a network cable to the modbus TCP port that connects with the slave device through the network.
BUS connection

It is recommended to use the Qbus cable or any other cable with a minimum of 2 conductors of 1mm² as the bus cable. The green shielded EIB cable can also be used if the conductors are paired to achieve a minimum cross-section of 2 x 1mm².
LED indicator on the module
PWR LED (green)
OFF: QMI module has no power via the bus
ON: QMI module has power via de bus
STATUS LED (red)
3 flashes, once: QMI module is starting up
1 flash + 3 flashes, once: when sending configuration from SMIII
RX LED (green)
ON: The QMI module receives Modbus data
TX LED (green)
ON: QMI module sends modbus data

Wiring diagram

Wiring diagram

General Cabling Example

Specific Example Cabling with Daikin RTD Modules

Through the SMIII, each module can be configured via the bus. This is clarified through our knowledge center.

When you have entered the serial number of a QMI/Pro20 in the window of the modules, the following window appears.

The QMI/Pro20 module facilitates the communication between the Qbus system and external HVAC devices via Modbus RTU or Modbus TCP/IP. The module acts as a Modbus master and enables the exchange of signals and statuses between a maximum of 20 slave devices and the connected Qbus I/O, with a total of 140 Modbus registers.

General Settings - Setup

Via the "Setup" button, you can determine the general settings of the QMI
- Communication settings: baud rate, parity, number of stop bits (RTU), polling delay (determines the waiting time between Modbus commands)
- Main Error Address: Here you can optionally assign an I/O that activates in case of a communication problem with one of the connected devices.
- Conversions: Here you have the option to add custom conversions, which will then be available for conversion selection in the register table.

Preconfigured Devices

Preconfigured types of devices are automatically loaded via “Wizard new device…”. This simplifies configuration and reduces errors in larger installations.
Upon selecting a type, the registers, function codes, and conversions are automatically configured. If you leave the '- New I/O -' option selected, a new Qbus I/O of the correct type will be created. If you wish to use an existing Qbus I/O, you need to select it from the 'Current data' list. If '- Same as row x -' is selected, the same I/O will be used as in the selected row.
Add selected lines to slave” button, you add the registers to the slave device.

Register Settings

Default settings for data format (16, 32, 64 bit, Float32/64), word order (Big endian, Little endian, Word swap), and signed/unsigned are automatically populated when adding registers.
Custom conversion formulas are available for each register.
Dynamic conversion tables adapt based on the choice of I/O type.

Slave Device Management

The name of the slave address can be changed at the top of the tab.
Settings of an existing slave address can be easily copied to a new slave address via the "Copy from..." button.

Control and Exclusion

Click on "Read Status" to view both the Modbus register (column "Modbus St.") and the Qbus I/O status of an IP or RTU device.
Certain lines can be temporarily disabled in the last column of the register table. Disabled lines are not sent upon uploading to the module but remain stored in the configuration on the PC.

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