Design and implementation of modbus slave based on ARM platform and FreeRTOS environment

The paper introduces the design of Modbus slave based on Modbus RTU over RS-485 and its implementation. By designing a new software architecture and embedded open stacks, development lifetime is shortened as well as the software is easy to port, maintain, and reuse. A new approach inspired from Modbus functionality makes it easier for developer to divide program into three tasks and synchronize them. An ARM based Modbus slave hardware is built and experiments have been carried out to validate that this Modbus slave is a reliable and stable communication system. It acquires many desired properties of an industrial embedded network software.