The Design And Implementation Of PLC Based On IEC61131

With the rapid development of science and technology today, PLC industry hasbeen prosperous all the time. Given the fact nearly all the PLC products are not toomuch satisfactory in terms of software compatibility, program portability, programreusability and data encapsulation, the International Electrotechnical Commission (IEC)sets the IEC61131Standard, a programmable logic controller standard to specify andimprove of the technology of programmable controller software and entire industrialcontrol software.The present thesis has deigned a brand new type of PLC that meets well theIEC61131Standard by studying of the system structure of IEC61131Standard, the basicprinciple of PLC and the instruction system of Hua-P language. This is favorable forsmall control system to make good use of its advantages such as low price,friendly-programming interface, straightaway programming language and easyunderstanding.The task this thesis intends to achieve covers two aspects. One is the designing ofboth PLC software and hardware systems. The software system adopts the currentobject-oriented C#programming language, which performs the main function of PLCsoftware system in the Visual Studio2008development platform. It gives emphasis onutilizing C#as the software development language based on components and help thePLC bring its potential into full play. The thesis has mainly realized the followingobjectives: the PLC equipped with the functions of the ladder diagram programming,instruction list programming and ladder diagram into instruction list. The other is thehardware system designing with CUP as its core part. This design of hardware systemhas completed such important functions as PLC power supply, input and outputinterface, communication interface and clock circuit. In the interest of the thesisresearch, the inexpensive but functional SM59264chip of the8051MCU series isadopted which is manufactured by Taiwan’s XinMao Company.The design of the PLC in accordance with the IEC61131standard is not only therequirement of industrial control, but the direction of PLC development in this field. The cost of PLC is lower, while the ladder-diagram as well as programming instructionlist is well involved. The PLC uses Hua-P language as its instruction list programminglanguage, which to a great degree enables Chinese industrial control technical personnelto learn and apply programming on their own. Therefore, the design of the PLC by thepresent thesis is practically valuable and promising in the future.