Research On Interpretation Method For PLC Programming Language And System Implementation

As a combination of automation technology, computer science technology and communication, Programmable Logic Controller has been widely used in industry control including machine manufacture, chemical process etc for its high performance, low cost and high reliability in hard environment. Currently, ladder diagram is one of main PLC programming languages. Function of ladder diagram instruction is implemented with CPU through the interpretation and execution of instructions. This dissertation, firstly investigates the principle of PLC and PLC programming language interpretive method in detail based on the implementation of instruction set of Mitsubishi FX2N series PLC ,and then carries out the interpretation and execution of PLC on Cygnal F040 single chip system. Fieldbus is a kind of digital, bi-directional serial data transfer and multi-branch communication network which connects intelligent equipment and automatic system. CAN bus is used in communication between PLC and CAN modules in this system.This dissertation includes main aspects as follow:1. Introduces the direction in PLC and Fieldbus and their features2. Makes an investigation of interpretive principles and key techniques of PLC ladder diagram language based on FX2N series PLC instruction set, and proposes interpretive methods of basic program instructions, SFC instructions and application instructions on Cygnal F040 single chip system, as well as the design and debugging of hardware and software.3. Analyzes the CAN controller of Cygnal F040. Configures CAN module by PC software according to the system's demand of expansibility for CAN module, and implements communication software between PLC and CAN module based CAN bus to the question of communication of CAN module and input sampling and output refurbish of PLC.