Modbus RTU to RS232 ASCII bridge – Cool4M

Cool4M is a universal gateway that translates Modbus RTU on RS485 to simple ASCII commands over RS232.

Product Description

Cool4M Modbus RTU to ASCII bridge provides and supports ASCII commands over RS232 interface and translates  them into ModBus RTU protocol over RS485, while eliminating the complexity of the Modbus interface.

modbus rtu

Main Features

  • Variable RS232 and RS485 baud rates
  • Configurable RS485 polarity
  • Compatible with Modbus specification
  • Fully compliant with EIA/TIA-485 standard
  • Customisable for specific user applications
  • Field Upgradable
  • Modbus RTU to RS232
  • Modbus RTU to ASCII


CooLink Compatible with


Cool4M is fully compatible with Modbus serial line protocol. Click here for MODBUS over serial line Specification and implementation guide.

CooLink Full Control

Comprehensive and self explanatory commands set

  • crd – Read Coils
  • drd – Read Discrete Inputs
  • hrd – Read Holding Registers
  • ird – Read Input Registers
  • cwr – Write Coils
  • hwr – Write Holding Registers
  • set – Cool4M Configuration
  • scan – Look for slave devices
CooLink - Plug and Play

Plug and Play device

The system is ready to work while no additional configuration setup will be required after connecting the wiring.

CooLink RS232

Seamless integration with Modbus driven Systems and PC applications

Interfacing with Cool4M is a simple and straightforward task requiring only common ASCII commands over RS232. Cool4M supports Unsigned/Signed Decimal and Hexadecimal presentation for values and addresses.

CooLink - Indoor Units Monitoring and Diagnostics

Error Detection & Reporting

Provides both Modbus native and Cool4M specific error codes and statuses.

SKU: CO4M Category:
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