CoolGate M

Modbus gateway for VRV/VRF Air Conditioning Systems


CoolGate-M is a versatile gateway device connecting VRV/VRF air conditioning systems (Daikin, Sanyo, Toshiba, Fujitsu, LG, Mitsubishi Electric, Hitachi & Mitsubishi Heavy) to BMS or any other industrial controllers. Using MODBUS RTU protocol CoolGate-M enables full control and monitoring of the indoor units and provides access to VRV system parameters (CoolGate-M Pro). In other words CoolGate-M hides complexity of internal air conditioning communication line (including very unique physical layer) and instead provides standard MODBUS RTU interface over RS485 communication network.


CoolGate M/ML (LG)


Product Feature

Easy to integrate with BMS and other industrial control applications

CoolGate-M is very simple and straightforward. Implementation of software is very simple and straightforward since ModBus is a well known open communication protocol.

Modbus RTU Interface  RS458 - icon

ModBus RTU Interface

CoolGate-M impose unified interface for each VRV/VRF manufacturer. It means for example that industrial control application working on Daikin VRV system with CoolGate-M will work exactly the same way on Mitsubishi Electric VRF, Sanyo VRF, Toshiba VRF, LG VRF and other systems. No special interface adaptation will be required to migrate from one system to another.

Full Control over Indoor Units Operation

On/Off control, Cool, Heat, Fan, Dry mode selection, Set Temperature Control, Fan Speed Control, Swing Control (for wall mounted and cassette indoor units), Filter Reset Sign, Group Operations (All On, All Off)

Indoor Units Monitoring

Failure Alarms, Set point temperature, Operation status (on/off) Operation mode (cool/heat/fan/dry), Fan speed (high/low), Filter sign, Swing.

System Diagnostics (CoolGate-M Pro)

Outdoor Units internal parameters: Condensing, Evaporation, Ambient Temperatures, EV Opening, System Power Consumption (current), Inverter Revolutions and others Indoor Units internal parameters: Return air, Gas and Liquid Temperatures, EV Opening. Those features are currently available for Daikin VRV, Mitsubishi Electric and Hitachi VRF air conditioning systems.

Field Upgradable

New Firmware can be uploaded via RS232 port. No need to open unit to change it's functionality.


Block Diagram

CoolMaster-Block Diagram






CoolGate-M LCD FAQ

Below is an example of information that can be reflected on CoolGate LCD.

In this example VRV system has 3 indoor units with external addresses 1.01, 1.02
and 1.03. You can gather following information looking at the CoolGate LCD.

Unit ON/OFF Set Temperature Fan Speed Mode Failure Code
1.01 OFF (-) 18° High Cool U4
1.02 ON (+) 20° Low Fan No (OK)
1.03 OFF (-) 18° High

The strange string U03 G03 A3 U4 means that there are 3 indoor units - U03 and 3 indoor units with preset external address - G03. Failure codes A3 and U4 were detected in system.

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  • RMA form



  • Utilities

    Telnet programs:

    PuTTY is a small telnet program that can provide an easy access to the device from PC/Laptop by RS232/USB connection.

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