MODBUS GATEWAY DESIGN USING ARM MICROPROCESSOR

INTRODUCTION Improvement of technology in automation system, different device technology and communication protocols are introduced. Data transmission speed, compatibility between devices, setup cost and maintenance become crucial with enlarging automation systems. The first remarkable criteria when setup an automation system is communication protocol. There are lots of research and development in industrial communication technologies to improve technical characteristics. For example, the devices use wired connection to support serial communication RS232 and CAN supply only point-topoint communication, low speed and limited transmission distance besides RS485 has supporting up to 32-128 nodes, high transmission speed, over transmission distance, low cost and strong antiinterference. Another wired communication technology is Ethernet is most used communication protocols because of good compatibility and easily connective, data rates is up to reach 10 megabits per second to 100 gigabits per second, including CSMA/CD standard to prevent data-collision [Shuangye Chen et al., 2013], [Li Hui et al., 2013]. Accordingly, MODBUS protocol can support both Serial and Ethernet communication. Modbus RTU is based on serial communication with RS232, RS485 and RS422 psychical layer since Modbus TCP is based on Ethernet TCP/IP protocol [Mihai Postolache, 2017], [Modbus Foundation]. Another research area is connection capacity. Programmable Logic Controllers (PLCs) are capable multiple interfaces, but the main purpose of this devices is implementing data acquisition and processing of data, not for packet processing and protocol handling. The price of PLCs and the time for man-hour to program the PLC functionality is enormous costs to solve complexity in the heterogenous network topologies [ClaudiuChiculita and Mihai Lucian Cristea, 2013]. The research concludes the requirements of gateway.The aim of this study is design and developing a Modbus gateway which is low cost, real-time, more connection capacity, reliable, convenient Serial-Ethernet communication through RS485 serial bus and Ethernet TCP/IP. The main purpose of the design is to make installation and setup the system easier with user interface and messaging interface and the second aim is designing a low cost, reliable and real time system. Since ARM Embedded System, FreeRTOS real time system,Ethernet and Serial line devices are met the target system requirements. For Detailed Description Refer original paper , download from here : IJISRR-552