Research Of An Embedded Server System Based On UClinux

With the rapid technical development of the comuputer, the communication and the automation, the requirement for the intelligent production grows more higher, remote-cotroll and no one on duty becomes the trend of modern industry pattern. Because of the limit of the technology, the widen-used PLC net and field bus net really can't realize the long-distance watch and control. Embedded server technology is a new technology with the rapid development of Internet & embedded applications, it enhances its abilities by adding the supply of Enternet, phone net and wireless network.This thesis focus on the construction of an embedded server, and its background is a project of how to remote control round-net printers through diffirent type of PLCs. The embedded server is the kernel of the whole embedded system, it communicates with PLCs through the serialport and with remote clients through net port. Anyone who is commissioned can control the field equipments by running a special computer program anywhere he can surf on the Internet.This article describles how to desingn an embedded server according to the collaborator's requirement. The server is constructed on the base of hardware platform of HHCF5272-LCD-IDE-R1 groupware of HuaHeng Company and on the base of software platform of uClinux. The paper firstly distributes some tasks according to the demand, and then, plans an application protocol on the base of TCP/IP protocol by distinguishing the interface of the server to PLCs and to the remote clients. The application protocol includes all parts of client demands, such as validating client's identity, validating client's popedom degree, uploading files & downloading files, configuring serial ports and net ports of the server, changing the picture of monitor, setting or inquiring the server's states, controlling the server's rebooting. The paper then analyzes some messurements of how to accelerate the response of the server, it includes three parts: the adoption of multi-threads, optimizing PLC resouse file. The adoption of multi-threads is to run different tasks in different prodecures at the same time, and the two prodecures shares data by IPC, the adoption of data buffer is to get PLCs' data to the buffer of computer, when many clients need to operate a same PLC the server only let the highest degree client do that and let others read data from the special buffer so that clients won't conflict with each other, optimizing PLC resouse file is to reset the PLCs' resource according to the special rule, so that server can read PLCs more quickly. After a series of management, many clients can not only work well, but also can improve the speed of the response.