Design Of PLC Programming Device Based On Embedded Microcontroller Processor

Aimed at the small Programmable logic Controller (PLC) adopting Embedded ARMmicroprocessor and FPGA as the control center in the Research Team, A type of portablePLC Programming Device is designed.According to the functional requirements of PLC Programming Device, theinstruction sheet is adopted as PLC programming language. An instruction system isdesigned, especially for multiple operations logic operation instruction. The PLCinstruction file is edited, compiled and decompiled. The programs are transmitted throughCAN bus. PLC host' working state can be remotly monitored. According to the generaldesign requirements and ideas of PLC Programming Device, LPC1768ARM Cortex-M3microcontroller is adopted as the control core of the hardware architecture, and uC/OS-IIsystem is adopted as the control core of the software architecture. Programs aredeveloped in Keil uVision4integrated development environment. JTAG emulator J-Linkis used to debug programs. Through the functional, performance and online tests, thereliability and feasibility of the device are verified. During the process of the researchmainly the following results gained:In the editing and compiling process, the mapping relationship among the instructionfile, the code file, ASCII character values table, bitmap fonts table and liquid crystaldisplay file are set up. The analysis and error detection are adopted to handle PLC sourceinstruction file, and the object instruction file is generated. The compilation technique isused, and instructions classification thought is adopted. The object instruction file iscompiled into object code file. In the process of the object code file decompiled, thedecompilation technology based on the static analysis method is adopted?the object codefile is compiled into the object instruction file, and then converted to the sourceinstruction file, and is displayed in the LCD screen. The whole process forms a reversedata flow.192KB Flash program memory on-chip of LPC1768microcontroller is usedas.nonvolatile PLC data memory. The IAP programming technique is used to store userprograms. The allocation maximum space of each user program is16KB. Up to12setsof programs can be stored. The existing programming device's small storage capacity, aset of PLC program be stored and other issues are solved. According to the designprinciple of FAT32file system, a PLC File system is designed, so as to be convenient toread, write and modify. The correctness and completeness of the datas are guaranteed. Button function reuse method is adopted to realize the software function of thekeyboard. LCD screen display format is planned. PLC source instructions, especiallymultiple operations logic operation instruction's display format are made, in order tomake the display more friendly. Command line feed display, rolling screen, refresh thescreen, and other diplay functions can be realized.PLC programming device and PLC host can be communicated through CAN bus. PLChost can be remotly debugged and monitored. The faults of the existing programmingdevice using a dedicated cable in close communication with PLC are overcomed. TheCAN communication extension agreement is formulated. According to the protocol, thedatas are transmitted, the status of soft components, the current value and the set value ofthe specify soft component are detected. The specified soft component's state, theparameters of data registers, timer and counter are mandated to be set.