Microcontroller-based modbus master design and implementation for multiple networks and platforms using object-based design technique

摘要

This research presents object-based design and implementation techniques to build a Microcontroller-based Multi-channel Modbus Master for industrial automation systems. The proposed Modbus Master is designed to support various kinds of slave devices. It can communicate to multiple types, vendors, protocols and communication properties of the target slave devices. The master device can choose and communicate to a target device by considering the slave information stored in object property fields. The object-based design technique is chosen to design proper objects of different slave devices. The system is designed to support multi-channel communication. Each channel (network) uses different communication port. Therefore, the master can independently communicate to slaves which are connected in different channel at the same time. The master is implemented in a 16-bit microcontroller having two UARTs communication ports. The communication ports are converted to RS-485 and used as Modbus networks. The master has its own storage memory (two MMC/SD cards), used as data storages. In addition, it can communicate to host computers and other devices through a USB port or LAN port. A special real-time event-driven kernel is design and used as an operating system to make the system operate appropriately. Also, some device drivers and utility functions are made. Because of the program is designed and implemented based on stand C language, so that it can be easily ported to other platforms of microcontrollers and computers. The proposed Modbus master is evaluated on real-time power monitoring system which has three different brands of digital power meters, Siemens, Panasonic and Iskra connected to the networks.