施耐德PLC讲座演示CC__E-公开课件（讲义）.ppt

Concept and the IEC Instruction List (IL) Concept Programming in IL Instruction List (IL) is a low level textual language which has a structure similar to a simple machine assembler. The IEC has developed IL by reviewing the many low level languages offered by PLC manufacturers. IL provides a wide range of operators that represent those most commonly found in proprietary instruction list languages of current day PLCs (e.g. AWL in A250 from AEG-Modicon). Concept Programming in IL Advantage: The basic structure of IL is very simple and easy to learn Ideal for solving small straight-forward problems where there are few decision points and a limited number of changes in program execution flow Tight, optimised and fast code for performance critical sections of a program (e.g. DFBs) Disadvantage: Difficult to write, read and understand the program Difficult to follow the program flow Concept Programming in IL With IL the following operations can be executed: logical (AND...), arithmetic (ADD...), compare (GT...) operations and assignments (ST, S, R). Jumps within a section unconditioned / conditioned (JMP / JMP C, JMP CN) Functions and function blocks unconditioned / conditioned (CAL / CAL C, CAL CN) Before invoking a FFB, it has to be declared using VAR and END_VAR. Each FFB instance must be invoked once. Multiple invocation (instatiation) is allowed! FFB-call: with CAL and a list of input parameters or with CAL and Load/Save of the input parameters or by using the input operators. Concept Programming in ILStructure Concept Programming in IL Operators LD N Loads the value of the operand into the Accu Literal, variable, direct address from data type ANY ST N Saves the value of the Accu in the operand Literal, variable, direct address from data type ANY S Sets the operand to 1 if the Accu content is 1 Literal, variable, direct address from data type BOOL R Sets the operand to 0 if the Accu content is 1 Literal, variable, direct address from