Implementation Of Modbus/TCP Protocol In The Application Of The WIFI Communication

Modbus protocol is applied to electronic controller, which is a common application layer protocol, and it has been successful applied in a variety control network (wired Ethernet, PROFBUS, CAN). Modbus/TCP protocol is applied to wired Ethernet communication. The TCP/IP protocol can be used in both a wired Ethernet transmission and can be used in a wireless network transmission, wireless network transmission can be achieved in WIFI communication. So in the design, combine Modbus/TCP protocol and TCP/IP protocol to complete Modbus/TCP protocol at WIFI communication requirements.In order to achieve the WIFI communication, on the hardware side, STM32 micro-controller is used as the control system and a system slave station, whose core is ARM. This paper takes Marvell company’s 88W8686 chip as the wireless technology solution. According to it’s reference hardware circuit, selects USI’s WM-G-MR-09 wireless module, completing the design of hardware circuit. On the software side, complete the μC/OS-Ⅱ operating system and Lwip protocol stack transplant on the controller, and using Modbus/TCP protocol at the application layer to realize the identity recognition about master station and slave station, keep a same time about station and slave station, and query data function demands. In addition, the Visual Studio 2008 is used to design the PC display interface, which can display the function of the master station and slave station. By analyzing the results of the whole test, verify the wireless data transmission method in the paper, which has certain reference significance and practical value.