| There are thousands of equipments such as sensors, detectors and card readers which mainly communicate with host computer through serial ports in the industrial automation field. Generally, host computer can only supply two or three serial ports, serial extending is needed when host computer communicates with multiple equipments. With business development, the numerber of external equipments which industrial controller need to control is growing, and the existing serial number could no longer meet the demand for serial. It is based on such needs that we design the serial ports expansion of industrial controller.The design of industrial controller's extending serial driver and Serial Application Software are detailedly introduced in the paper, when using TL16C554 asynchronous communication element to extend serial ports of the industrial controller whose CPU is ARM microprocessor and operation system is Windows CE EOS.Embedded development is related to special hardware platforms and hardware driver is the foundation for development. The development of serial driver which works in the interrupt mode in Windows CE.net EOS is detailedly introduced in the part of driver design, and the driver's loading process, interrupt handling of stream device, the design of layered serial driver and the modification method of files such as register file, CEC and BIB file are highlighted.Serial Communication Software is designed to test if the extended ports can be used normally. Besides, it is also designed to help developers operate serial ports. Its main functions include opening, closing, reading and writing serial ports and the configuration of serial communication parameters. The method and process of realizing RS232 serial communication are detailedly introduced in this part, and the method of using multithreading technology to realize similar asynchronous serial communication and the design of serial communication class are highlighted. |
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