Instruction List (IL)

Introduction

Instruction List (IL) is a list of instructions, similar to assembly language, that are run in order.

Instruction List is one of the five programming languages defined the IEC 61131-3 standard.

The Instruction List uses this syntax:

instruction-list ::= { instruction-item }

instruction-item ::= [ label | instruction ]

label ::= identifier ':'

instruction ::= <See table below>

Fernhill SCADA supports these types of instruction:

These load and store instructions are supported:

Instruction	Comment
LD Expression	Sets the current result to the value of Expression. For example: LD 1 LD X LD X[0]
ST Variable Reference	Stores the current result to a variable. For example: ST X ST X[0]
S Variable Reference	If the current result is TRUE, sets Variable Reference to TRUE. For example: S X
R Variable Reference	If the current result is TRUE, resets Variable Reference to FALSE. For example: R X

These logical instructions are supported:

Instruction	Comment
AND Expression	Sets the current result to: Current Result AND Expression. For example: AND 16#FF
ANDN Expression	Sets the current result to: Current Result AND NOT( Expression ). For example: ANDN 16#FF
OR Expression	Sets the current result to: Current Result OR Expression. For example: OR 16#80
ORN Expression	Sets the current result to: Current Result OR NOT( Expression ). For example: ORN 16#80
XOR Expression	Sets the current result to: Current Result XOR Expression. For example: XOR 16#F
XORN Expression	Sets the current result to: Current Result XOR NOT( Expression ). For example: XORN 16#F
NOT	Sets the current result to: NOT Current Result. For example: NOT

These arithmetic instructions are supported:

Instruction	Comment
ADD Expression	Sets the current result to: Current Result + Expression. For example: ADD 1
SUB Expression	Sets the current result to: Current Result - Expression. For example: SUB 1
MUL Expression	Sets the current result to: Current Result * Expression. For example: MUL 5
DIV Expression	Sets the current result to: Current Result / Expression. For example: DIV 10
MOD Expression	Sets the current result to: Current Result MOD Expression. For example: MOD 7

These comparison instructions are supported:

Instruction	Comment
GT Expression	Sets the current result to: Current Result > Expression. For example: GT 7
GE Expression	Sets the current result to: Current Result >= Expression. For example: GE 7
EQ Expression	Sets the current result to: Current Result = Expression. For example: EQ 7
NE Expression	Sets the current result to: Current Result <> Expression. For example: NE 7
LT Expression	Sets the current result to: Current Result < Expression. For example: LT 7
LE Expression	Sets the current result to: Current Result <= Expression. For example: LE 7

After a comparison instruction the current value will be either TRUE or FALSE.

These control flow instructions are supported:

Instruction	Comment
JMP Label	Jump to Label. For example: JMP Start
JMPC Label	Jump to Label if the current value is TRUE. For example: JMPC Found
JMPNC Label	Jump to Label if the current value is FALSE. For example: JMPNC Error

In Fernhill SCADA you can use Instruction List code in:

A Program Tag to execute on the SCADA Server. Programs written this way can be run:
- On a schedule.
- Triggered by an event.
- A combination of schedule and event.
A Graphic Page User Actions to run in the Operator Interface. Code is run in response to a user interacting with a graphic page.
An Operator Toolbar Icon Actions to run in the Operator Interface. Code is run in response to a user clicking a toolbar button.

IEC 61131-3 Second Edition: Table 52.

IEC 61131-3 Third Edition: Table 68.

To learn about IEC 61131-3 Common Elements you can use in IL programs and functions.

For the meaning of terms used in Fernhill SCADA.