Design And Development Of The Safety Input/Output Board Programmer For Computer Based Interlocking System

In an independent research of safety computer based interlocking system, safety input/output board is designed using security code to ensure the safety of acquisition and driving. Since secure codes need to be programmed into the safety input/output board’s flash memory previously, for security reasons, after the system launch, the security codes storied in the flash can only be read online, can’t be erased, which means does not support online programming. So we need to design an off-line programmer to program for the safety input/output board. At the same time, we need to design PC program to read the security code data file, through the programmer to download the security code into the safety input/output board’s flash memory, and read back the data to verify the accuracy of the security data in the interlocking system. Whether the design of programmer system is good or bad, directly related to the security of the computer based interlocking system’s hardware platform, and the efficiency of subsequent project configuration.The flash chip used on the safety input/output board is 28F128J3F75 nor flash. Through studying the performance of the chip and its read/write timing, address lines and data lines, determined the function requirements and the necessary input/output pins of the programmer board. Considering the above factors and the project schedule requirements, combined with my own development experience, designed a programmer with 80C51F020 as its core controller, and designed the PC program based on Qt to realize the operation of the flash memory on the input/output board, including automatic identification of input/output board, read the flash information, program and validate security code, etc.The programmer board is designed compact and small, and the PC program interface is designed simply and friendly, which can guide the users to operate. Test and debug only need a laptop. Under the 115200 baud rate, the read and write speed of the security code reached 14k Bytes/s and 7k Bytes/s, fully meet the demand of engineering application. At present the system has been applied in the test work of this type computer based interlocking system’s hardware platform, the performance is stable and reliable.