Embedded Soft Plc Based On Iec61131-3 Standard Study

The embedded softPLC system, which is based on IEC61131-3 standard, is theresult of the combination of embedded system and PLC in the modern industry control.With the rapid development of computer technology, communication technology andmicroprocessor technology, nowadays, the process control becomes more and morecomplex and the demand of control becomes higher than the before (for example theprocess control and fuzzy control). Besides, the control tends to decentralization andindividuation. Because of some flaws, the traditional PLC can't work well in theseaspects. However, the IEC61131-3 standard has promoted the PLC to openness todeveloping. According to this standard, the computer resource, communicationtechnology and field bus technology are full utilized. Based on software technology, anew opening architecture, namely softPLC, is used to realize the control function oftraditional PLC. The softPLC, which is based on embedded system, takes the advantageof embedded platform effectively. It improves the reliability and stability of the controlprocess. Now, it becomes a trend of adopting softPLC that is based on embedded systemto substitute for traditional PLC in automation field.The softPLC that based on embedded system has a lot of characteristics, such aspredominant capability, excellent quality, expansibility, transplant capability, real timecapability and open capability and so on. It overcomes some flaws of traditional PLC,because it can complete the control process while the latter can't. It improves thecontrol level and efficiency for enterprise. The whole system has integrated a lot ofadvanced technology, especially communication technology. The integration fromequipment control and management to effective enterprise management has beenrealized.This system is based on embedded system platform, using the S3C2440Aprocessor (ARM920T kernel) of Samsung corporation and the WinCE as embeddedoperating system. The design of hardware platform conformed to openness standard.The transform model of all program languages in light of IEC61131-3 standard isestablished. Furthermore, the structure define of middle language is a new opening architecture. It sustains data structure, powerful internet capability, friendly human andmachine interface. Also, it can carry on some complicated control algorithm.This paper firstly analyses the structure of the embedded softPLC system, which isbased on IEC61131-3 standard. The concrete realization scheme of the whole system isalso put forward in this paper. The hardware platform of embedded system conformedto openness standard is designed and developed according to this scheme. Then thedesign of soflPLC system, which conformed to IEC61131-3 standard is introduced indetail. Considering the bad environment of the modern industry control and need torealize some more complicated control algorithm, the design of hardware platformadopts the mode of S3C2440A chip plus WinCE embedded OS. The memory of thissystem adopts two pieces of K4S561632E-UC75 32M SDRAM and one 64M K9F1208NAND Flash chip made by Samsung corporation and one 16M 28F128 NOR Flash chipmade by Intel corporation. The chips can guarantee the reliability and stability for thesystem. The design of softPLC run environment adopts modularization theory. The FBsand functions are defined according to IEC61131-3 standard. Moreover, the middlelanguage transformation model is established, and the algorithm of compiling to targetcode is realized.The paper laid a good groundwork for the further research, such as the realizationof the field bus, distributed control, and remote control and monitoring etc.