IEC 61131-3 Program

Introduction

A Program is a sequence of statements executed in order. You can execute a Program in one of two ways:

Create a Program Tag to execute code in Fernhill SCADA
Add a Program declaration to the Global Bindings of a Graphic Page

Syntax

A Program uses this syntax:

program ::=
PROGRAM program-name
{ variable-declaration }
[ program-code ]
END_PROGRAM

program-code ::= [ structured-text | sequential-function-chart | instruction-list ]

Where:

program-name is the name of the program. This must be a valid Identifier.
variable-declaration defines the variables available to the Program. You can declare multiple blocks of variables.
program-code is the code to run.

Remarks

Use any of the following for the program-code:

A Program can reference other Functions and Function_Blocks.

Examples

Use Structured Text to add together tree three tag values and places the result in a global variable:

Var_Global
    (* Global variable storing total current *)
    PumpStationCurrent : LREAL;
End_Var

Program CalcTotalCurrent
    (* Calculate total current and store in a global variable *)
    PumpStationCurrent := %"PumpStation.Motor1Current" +
        %"PumpStation.Motor2Current" +
        %"PumpStation.Motor3Current";	
End_Program

Standards Compliance

IEC 61131-3 Second Edition: Table 39.

IEC 61131-3 Third Edition: Table 47.

Further Information

Program Units

To learn about other program units.

Variable Declarations

To learn about variable declarations.

Structured Text

To learn about Structured Text.

Sequential Function Chart

To learn about Sequential Function Charts.

Instruction List

To learn about Instruction List.

Glossary

For the meaning of terms used in Fernhill SCADA.