ABB ST语言编程

System 800xA Training

Chapter 13Structured Text

TABLE OF CONTENTS

Chapter 13 Structured Text............................................................................................................................................................1

13.1 General Information...........................................................................................................................................................2

13.1.1 Objectives....................................................................................................................................................................2

13.1.2 Legend.........................................................................................................................................................................2

13.1.3 Reference Documentation...........................................................................................................................................2

13.2 Structured Text...................................................................................................................................................................3

13.2.1 Advantages of Using Structured Text..........................................................................................................................3

13.2.2 Structured Text Editor.................................................................................................................................................4

13.3 Basic Language Elements...................................................................................................................................................5

13.3.1 Assignment Statements................................................................................................................................................5

13.3.2 Comment Statements...................................................................................................................................................5

13.3.3 Operators.....................................................................................................................................................................6

13.3.4 Precedence...................................................................................................................................................................7

13.3.5 Conditional Structures.................................................................................................................................................8

13.3.6 Iteration Structures......................................................................................................................................................9

13.3.7 RETURN Statement..................................................................................................................................................10

13.4 Functions and Function Blocks........................................................................................................................................11

13.4.1 Functions...................................................................................................................................................................11

13.4.2 Function Blocks.........................................................................................................................................................11

13.4.3 Declaring Function Block Instances..........................................................................................................................12

13.4.4 Calling a Function Block Instance.............................................................................................................................12

13.5 Common Mistakes and their Error Messages...................................................................................................................15

13.5.1 Identifier, Constant or Opening Parenthesis Expected..............................................................................................15

13.5.2 Variable Name is not Unique....................................................................................................................................15

13.5.3 Identifier Too Long or Invalid...................................................................................................................................16

13.5.4 Undefined Function Block.........................................................................................................................................16

13.5.5 Type Mismatch in Assignment..................................................................................................................................17

13.5.6 Incompatible Types in Expression.............................................................................................................................17

13.5.7 Declaring Variables from Error Messages.................................................................................................................18

13.6 Changing from ST to Function Block in Online mode.....................................................................................................19

Chapter13-1