An RTOS-based design for inexpensive distributed embedded system

This paper presents a case study in which an inexpensive embedded control system has been designed and built on top of an open-source real-time operating system. A COTS protocol stack for the well-known MODBUS protocol has been selected and enhanced to provide network communications with a wider address space and a periodic election of the bus master. This design technique has proved very effective to reduce software development time and cost, without incurring in the overhead and footprint issues sometimes associated with COTS software modules. The whole system runs effectively even on low-cost microcontrollers and can be ported easily from one microcontroller family to another.