Design And Implementation Of The Module Of Uart To Modbus-TCP Client

With the development of information technology, a lot of equipment in the field of industrial control requires internetworking, and along with Ethernet technology developing into the trend of low memory and low capacity, the embedded Ethernet technology emerges according to the need. In the field of industrial control, the physical interface layer of much equipment uses a serial port connection. The serial port equipment has defects of short transmission belt width, short transmission distance and high cost of wiring, weak anti-interference ability, but Ethernet technology overcomes the shortcomings mentioned above, so converting serial device into Ethernet device is more conducive to form a network. Modbus protocol is one of the popular fieldbus, and it has advantages of simplicity, efficiency and stability, so it is our first choice in the application layer design. Under this background, we put forward in this paper, the research subject of turning Uart to Modbus TCP client design and implementation.After full investigation and research, to choose cost-effective stmicroelectronics production Cotex-M3STM32F107series single chip processor as the hardware carrier of kernel, to use Keil, Modbus Salve, SecureCRT development and debugging tools to form the development environment, and to choose domestic RT-operating system Thread, the Swiss academy of sciences of the LwIP TCP/IP protocol stack, open-source Lib-Modbus Modbus protocol as the basic of software. Putting the software together, and writing various peripheral driver and application software, including read and write Flash drives, TCP applications, serial port application, Modbus client applications on the basis of the software. According to the system requirements for instructions,I have designed the command protocol and specification carefully.Through designing and debugging, I have completed8kinds of basic operation of Modbus TCP, and have carried on the functional testing and performance testing. Except reading and writing more to keep a register of functions, most functions have been implemented. In respect of performance, sending commands at the interval of100ms does not have error. The shortcoming in design is that it can not integrate multiple instructions into one when they arrive at the same time in operating the Modbus protocol to improve the efficiency of execution. When performing operations on design of module, it is recommended that after sending the order, waiting for the module of the response of the execution to send next instruction, which will lead to a more stable system.