Design And Implementation Of The Ethernet Serial Servers Based On The Cortex-M3

In the traditional access control system, pos consumption systems, attendance systems, security systems, medical equipment systems and industrial control collar, there are numerous sensor, card reader, detector, and so many other field devices need to be connected together in order to collect data. When the transmission distance is relatively short, the serial communication is easy to implement and maintain, and also can ensure high security of data transmission performance. Precisely because of this characteristic, serial communication is widely used in various fields. However, Serial communication transmission speed is slow, the transmission distance is relatively close, and there is a big defect in the reliability of transmission, If using Serial Bus communication to deal with data transfer between the remote host even multiple hosts and hundreds of sensors, detectors or other field devices the control networks will be extremely complex task. Due to the limitations of the serial communication technology itself, relying solely on it to achieve Data transfer between the remote host and the sensors, detectors, or other field device of the control system will exist many limitations obviously, so it is detrimental to the development of the automation control system.With the development of computer technology, automation control technology and communications technology, the traditional control technology is experiencing an unprecedented innovation, and is going to networked gradually. Demand of the voice signal, image signal and so on which require large amount of data and high speed prompting the joint of the Ethernet which is now prevalent in the industry and control network.According to the characteristics of the industrial control environment, this article design a low-cost embedded serial device server based on micro-controller LPC1768which contain a Cortex-M3core. The serial device server make multiple RS-485serial devices which scattered in the industrial control field level seamlessly access into the industrial Ethernet.So it can achieve the distributed intelligent management for data collection, data transmission and device control of the industrial monitoring.The main content of this thesis is to introduce the significance and role of the serial device server in the control system, and implement the complete design of the serial device server based on the microprocessor LPC1768which is Cortex-M3architecture and32high performance and low-cost, embedded operating system μC/OS-II and embedded TCP/IP protocol stack.The design includes the contents of three parts:1. The hardware platform designed around LPC1768mainly include Ethernet interface circuit, power supply circuit, reset circuit, serial port expansion circuit, debug circuit and level shifting circuit;2. The design of device firmware mainly include the migration of the TCP/IP protocol and μC/OS-II operating system,and the design of data forwarding procedure;3. Device driver include the design of virtual serial port driver.Finally, many experiments and tests show that the system can carry two-way communication, and transfer data correctly and completely, and PC can access to the serial link through virtual serial port, and the system achieved16serial port expansion.This Ethernet serial device server has the advantages of reliable performance, small size, low cost, low power consumption and so on, it is suitable for industrial control environment, and it meets the actual demand.