English | 日本語


Modbus RTU (Remote Terminal Unit) is an open, serial (RS-232 or RS-485) protocol derived from the Master/Slave architecture. It is a widely accepted protocol due to its ease of use and reliability. Modbus RTU is widely used within Building Management Systems (BMS) and Industrial Automation Systems (IAS).

The SoftDEL Solution

SoftDEL offers a ready Modbus RTU Master and Slave Stack on royalty free basis. The stack enables faster firmware development of Modbus-enabled field devices. The stack is useful for OEMs who wish to add Modbus RTU support for their field devices.

We also offer services such as porting of Modbus stack to device platform, integration with device application and complete product testing.


  • Stack is developed in ‘C’ language and can be ported to any Microcontroller platform
  • Ideal for Non-RTOS & can be ported to any RTOS platforms
  • Supports all the major Modbus functions, Diagnostic functions & Exception functions
  • Tested with various Modbus testing tools such as Wingpath, Modbus Poll, and Modbus Slave
  • Tested with all the major Baud rate (9600, 19200, 38400, 57600 & 115200) and with all the parity settings
  • Implementation as per Modbus Specification documents -Modbus_Application_Protocol_V1_1b3, Modbus_over_serial_line_V1_02
  • Memory footprint –
    • Master stack – RAM (3.64 KB), ROM (6.052 KB)
    • Slave stack – RAM (3.5 KB), ROM (11.85 KB)

Download – Functions supported by SoftDEL’s Modbus-RTU Stack