Omron IPC Machine Controller Industrial Panel PC / Industrial Box PC. Software User’s Manual (Industrial PC Platform NY-series)

6 Programming

Connecting line

The straight horizontal lines that connect the bus bar and the configuration elements are called con-

necting lines. Connecting lines can be either TRUE or FALSE and can transfer the power flow from

the left to the right.

Inputs

Inputs are placed along the connecting line to receive the power flow and operate accordingly.

There are several different types of inputs and, depending on their specifications, they will either

transfer the power flow from the left to the right or prevent the power flow from passing through.

When an input transfers the power flow to the right, the connecting line to the right of the input will

become TRUE. If the power flow is inhibited, the connecting line to the right of the input will remain

FLASE. For detailed specifications on inputs, refer to the NY-series Instructions Reference Manual

(Cat. No. W560).

Output

Outputs are placed along the connecting line to receive the power flow and operate accordingly. An

output writes the TRUE or FALSE value to a variable. There are different types of outputs. For

detailed specifications on outputs, refer to the NY-series Instructions Reference Manual (Cat. No.

W560).

Functions and Function Blocks

Functions and function blocks are placed along the connecting line to receive the power flow and

operate accordingly. For detailed instruction specifications, refer to the NY-series Instructions Refer-

ence Manual (Cat. No. W560).

Order of Execution for Ladder Diagrams

Inputs, outputs, functions, and function blocks are executed when they receive the power flow. The

order of execution for a ladder diagram is from top to bottom. Elements at the same level are executed

from left to right.

Ladder Diagram Completion

A ladder diagram is executed in order from top to bottom. When the execution reaches the very bottom,

the process is completed. However, the process will also end if an END or RETURN instruction is

encountered at any point during the process. No processes after those instructions are executed.

Controlling Execution of Ladder Diagrams

Ladder diagrams are generally executed from top to bottom, but you can use execution control instruc-

tions to change the execution order. In the following example, when the value of program input a

changes to TRUE, execution will move to the point labeled ‘ExceptionProcessing.’

Input a

Label: ExceptionProcessing

Input b

Input c

Label: ExceptionProcessing

Input d

Input e

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6 Programming

Connecting Functions and Function Blocks in a Ladder Diagram

z Connection Configurations

You use the following two types of connections for functions or function blocks.

1) Power Flow Input and Output

In a ladder diagram, the line that connects an input variable of a function or function block and the

left bus bar indicates a BOOL input and the line that connects an output variable to the right bus bar

indicates a BOOL output.

Example:

Inputs are connected in the power flow that connects to the left bus bar. Outputs are connected in

the power flow that connects to the right bus bar.

IN1

OUT1

IN2

OUT2

2) Parameter Inputs and Parameter Outputs

In a ladder diagram, parameter inputs and outputs are specified when the input and output variables

of a function or function block are not connected to the left and right bus bars.

IN1

OUT1

IN2

OUT2

As shown below, you can specify either variables or constants for input and output parameters.

Function/function block variables

Input parameters

Output parameters

Input variables

You can specify variables or con-

---

stants.

Output variables

---

You can specify only variables.

In-out variables

You can specify only variables.

Number of BOOL Variables

At least one BOOL variable each is required for the input and the output (such as EN and ENO) of a

function or function block.

Example:

BOOL variable

MyFB

(BOOL)

(INT)

Val_In

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6 Programming

Connections Based on the BOOL Variable Positions

The top BOOL variables are connected to the left and right bus bars. In other words, they become

the power flow input and power flow output.

Top BOOL

variable

MyFB

(BOOL)

(INT)

Top BOOL variable

Val_Out

(INT)

(BOOL)

Val_In

Power flow

There is only one power flow input and one power flow output for each function or function block. All

other BOOL variables that are not at the top are for parameter inputs and parameter outputs.

MyFB

(BOOL)

(INT)

IN1

Val_Out

BOOL variable that is not

BOOL variable

(INT)

(BOOL)

at the top

that is not at the

Val_In

top

(BOOL)

IN2

Parameter output

Parameter input

You cannot connect multiple BOOL variables to the left bus bar or the right bus bar as shown below.

(BOOL)

Set

(BOOL)

Reset1

MyFB

(BOOL)

(INT)

Val_Out

(INT)

(BOOL)

Val_In

(BOOL)

You do not have to connect an OUT instruction to the right bus bar. You can connect the function or

function block directly.

MyFB

(BOOL)

(INT)

Val_In

A LD instruction is not necessarily required. You can also connect directly to the left bus bar.

MyFB

(BOOL)

(INT)

Val_In

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6 Programming

Cascade Connections

Cascade connections in which the output of a function or function block is connected to the input of

another function or function block are allowed only for power flow outputs and inputs.

Example:

CIPRead

(BOOL)

Execute

Done

Execute

Done

(BOOL)

Handle

Busy

Handle

Busy

(BOOL)

SrcDat

Error

SrcDat

Error

(BOOL)

Size

ErrorID

Size

ErrorID

(BOOL)

DstDat

(BOOL)

ErrorIDEx

(BOOL)

RcvSize

MyFB

(BOOL)

(INT)

Val_Out

MyFB

(INT)

(BOOL)

(INT)

Val_In

Val_Out

(INT)

(BOOL)

Val_In

You can branch the power flow output.

Example:

CIPRead

(BOOL)

Execute

Done

Execute

Done

(BOOL)

Handle

Busy

Handle

Busy

(BOOL)

SrcDat

Error

SrcDat

Error

(BOOL)

Size

ErrorID

Size

ErrorID

(BOOL)

DstDat

(BOOL)

ErrorIDEx

(BOOL)

RecvSize

CIPRead

(BOOL)

Execute

Done

(BOOL)

Handle

Busy

(BOOL)

SrcDat

Error

(BOOL)

Size

ErrorID

(BOOL)

DstDat

(BOOL)

ErrorIDEx

(BOOL)

RecvSize

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6 Programming

Restriction

• You cannot create closed loops or intersect connecting lines.

Example:

FB1

FB2

ENO

IN1

OUT1

OUT

IN2

OUT2

No closed loops

z Reversing Inputs

You can reverse the value of a BOOL input variable when you input it to an instruction.

NOT input

(BOOL)

TRUE→FALSE

FALSE→TRUE

Inline ST

z Introduction

Inline ST is a ladder diagram programming element in which you can write ST language code in a

box called an inline ST box (a blank text input area) within a ladder diagram. This allows you to eas-

ily code numeric data processing and text string processing within ladder diagrams. The connecting

line to an inline ST box becomes its execution condition. The ST code inside of the box is executed

based on that connecting line. Refer to the following figure.

Execution Condition for Inline ST

Inline ST

Inline ST box

taiseki := 4.0 * 3.14 * radius *radius * radius / 3.0;

Enter the ST language code here.

Inline ST is treated as a rung element in a ladder diagram. Therefore, unlike functions and function

blocks, they have no input, output, or in-out variables.

z Restrictions for Inline ST

You can write ST language code in inline ST boxes.

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6 Programming

z Execution Conditions for Inline ST

The execution conditions for inline ST are shown in the following table.

Status

Operation

TRUE execution condition

Operation follows the execution condition. You can use the execution con-

dition at any point in the power flow (e.g., you can connect the inline ST

directly to the left bus bar). To specify a change to TRUE or a change to

FALSE, specify it for an input in the execution condition.

FALSE execution condition

Nothing is done.

Resetting in a master control

Nothing is done.

region

z Scope of Variables in Inline ST

The scope of variables that you can access from inline ST is the same as the POU of the ladder dia-

gram that contains the inline ST.

z Restrictions for Inline ST

Item

Description

Number of inline ST boxes per rung

6-5-3

Structured Text Language

The ST (structured text) language is a high-level language code for industrial controls (mainly PLCs)

defined by the IEC 61131-3 standard. The standard control statements, operators, and functions make

the ST language ideal for mathematical processing that is difficult to write in ladder diagrams. The fea-

tures of ST are described below.

• Loop constructs and control constructs such as IF THEN ELSE are provided.

• You can write programs like high-level languages such as C, and you can include comments to make

the program easy to read.

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Structure of ST

ST code consists of one or more statements. One statement is the equivalent of one process. State-

ments are executed from top to bottom, one line at a time, until the process is completed. Statements

are made up of keywords and expressions. A keyword is a symbol or string that expresses assignment

or execution control. An expression is a code that calculates a value from variables, constants, function

return values, and/or a combination of those, along with various operators. A statement represents a

process that completes by itself. Expressions form a statement by using a combination of values and

keywords.

Example of an Assignment Statement:

Assignment

Variables Operators Constant Return value of function

keyword

Comment

A:= B

100

* ABC (10, 20) ; (*Assign A to B + 100 * ABC (10, 20)*)

Expression

Example of an IF Construct:

IF keyword

IF D = E + 100 * DEF(10,20) THEN

Expression

(*TRUE if D and E+100*DEF(10,20) are equal, otherwise FALSE*)

G := H ;

Statement

IF keyword

END_IF ;

ST Language Expressions

z Statement Separators

• Statements must end with a single-byte semicolon (;). Statements are not considered complete

with only a carriage return at the end. This allows you to write long statements across multiple

lines.

• One statement must end with one single-byte semicolon (;). In the following example, the IF con-

struct contains a single assignment statement. Each statement must be ended with a single-byte

semicolon (;).

IF A=B THEN

Assignment

C := D;

IF construct

statement

END_IF;

z Comment

• You can write comments in your program to make the code easier to understand.

• Statements written as comments are not executed.

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• The two methods to insert comments are described below.

Comment notation

Examples

Remarks

Enclose the comment in sin-

(* Commenting out multiple lines

This type of comment can span over

gle-byte parenthesis and

multiple lines. Comments cannot be

IF ErrCode = 3 THEN

asterisks, for example,

nested.

Value := 1000;

“(*This is a comment*)”.

END_IF;

down to here. *)

Begin the comment with two

// Comment

You can comment out only single

forward slashes (//) and end

lines.

// A := SIN(X)^2;

it with a carriage return.

Spaces, Carriage Returns, and Tabs

• You can place any number of spaces, carriage returns, and tabs in your code at any location. This

allows you to add spaces or tabs before statements and carriage returns between operators/key-

words and expressions in order to make your code easier to read.

• Always enter a token separator, such as a space, carriage return, or tab, between operators/key-

words and variables.

Example: The square boxes indicate where you must insert a token separator, such as a space,

carriage return, or tab.

IF  A>0  THEN  X:=10;

ELSE 

X:=0;

END_IF;

Lowercase/Uppercase, Single-byte/double-byte Characters

• Operators, keywords, and variable names are not case sensitive.

• Operators, keywords, and variable names must always be in single-byte characters. A syntax

error will occur if you input double-byte characters.

Variables and Prohibited Characters

Refer to 6-3-12 Restrictions on Variable Names and Other Program-related Names for restrictions

on variable names.

Text Strings

Refer to 6-3-12 Restrictions on Variable Names and Other Program-related Names for restrictions

on text strings.

ST Keywords and Operators

z Statement Keywords

Keyword

Meaning

Example

Assignment

d := 10;

Calling functions and

FBname(para1 := 10, para2 := 20);

function blocks

Refer to Function Block Calls on page 6-121.

RETURN

Return

IF d < e THEN f := 1;

ELSIF d = e THEN f :=2;

ELSE f := 3;

END_IF;

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6 Programming

Keyword

Meaning

Example

CASE

Case

CASE f OF

1: g :=11;

2: g :=12;

ELSE g :=0;

END_CASE;

FOR

For

FOR i: = 100 TO 1 BY -1 DO

Val[ i ] := i;

END_FOR;

WHILE

While

WHILE Val < MaxVal DO

Val := Val + 1;

END_WHILE;

REPEAT

Repeat

REPEAT

Val := Val + 1;

UNTIL( Val > 4 )

END_REPEAT;

EXIT

Exit the loop.

FOR i := 1 TO 100 DO

FOR j := 1 TO 10 DO

IF Val[ i, j ]>100 THEN EXIT;

END_IF;

END_FOR;

;

Empty statement

Val[ i ] := i

; (* Empty statement *)

WHILE(Var <>0) DO

; (* Empty statement *)

END_WHILE;

(* Text *)

Comments

(* Commenting out multiple lines

IF MyFun (ErrorCode) = 3

THEN ReturnValue := GetDetail();

END_IF;

down to here. *)

//Text

Comment

A := SIN( X ) ^ 2 + COS ( Y ) ^2 + 10;

// A := SIN( X ) ^ 2 + COS ( Y ) ^2 + 5;

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6 Programming

Operators

The following table gives the operators and their order of priority.

If operators with different priorities are mixed in one expression, the operators with the highest prior-

ities are executed first. You can use up to 64 operators in one expression.

Example: X:=(1+2)−3*4; In this case, variable X is assigned a value of −9.

1. The operation in

2. The multiplication

3. The subtraction

parentheses (priority

(priority of 5) is

(priority of 6) is

of 1) is performed.

performed.

(1+2)−3*4

3−3*4

3−12

−9

Operation

Operator

Notation example and evaluated value

Priority

Parentheses

()

(1+2)*(3+4)

Value: 21

Function/function

FUN1( FUN2( Var2A, Var2B), Var1B)

block call

When function and function block calls are nested, the

function or function block at the lower level is called first. In

the above example, FUN2 is executed first, and then FUN1

is executed.

Sign

+, −

+100

−100

NOT

NOT TRUE

Value: FALSE

Exponent

-2**2

Value: 4

A minus sign is given priority over an exponent operator.

Therefore, -2**2 in the above example is the same as (-

2)**2, so the value is 4.

2**3**2

Value: 64

If there is more than one exponent operator, calculations

are performed for them left to right. Therefore, 2**3**2 in

the above example is the same as (2**3)**2, so the value is

64.

Multiplication

100*200

Value: 20,000

Division

100/200

Value: 0.5

Remainder

MOD

10 MOD 7

Value: 3

−17 MOD 6

Value: −5

−17 MOD (−6)

Value: −5

17 MOD 6

Value: 5

17 MOD (−6)

Value: 5

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Operation

Operator

Notation example and evaluated value

Priority

Addition

100+200

Value: 300

Subtraction

−

100-200

Value: −100

Comparison

<, >, <=, >=

100<200

If the comparison result is TRUE, the value is set to TRUE.

Otherwise, the value is set to FALSE. In the above exam-

ple, 100 is less than 200, so the value is TRUE.

Matches

100=200

If the two values match, the value is set to TRUE. Other-

wise, the value is set to FALSE. In the above example, 100

does not equal 200, so the value is FALSE.

Does not match

< >

100<>200

If the two values do not match, the value is set to TRUE.

Otherwise, the value is set to FALSE. In the above exam-

ple, 100 does not equal 200, so the value is TRUE.

Logical AND

AND,&

Applies 1-bit AND logic to all bits.

The results of 1-bit AND logic are as follows:

0 AND 0 = 0

0 AND 1 = 0

1 AND 0 = 0

1 AND 1 = 1

0101 AND 1100

Value: 0100

Logical exclusive

XOR

Applies 1-bit exclusive OR logic to all bits.

The results of 1-bit exclusive OR logic are as follows:

0 XOR 0 = 0

0 XOR 1 = 1

1 XOR 0 = 1

1 XOR 1 = 0

0101 XOR 1100

Value: 1001

Logical OR

Applies 1-bit OR logic to all bits.

The results of 1-bit OR logic are as follows:

0 OR 0 = 0

0 OR 1 = 1

1 OR 0 = 1

1 OR 1 = 1

0101 OR 1100

Value: 1101

Precautions for Correct Use

The intended operation may not occur if a function is nested under itself. Always separate the

functions into different statements as shown below.

Example of incorrect notation: out := MyFunc( In1:=x1, In2:=MyFunc( In1:=x2, In2:=x3 ) );

Example of correct notation: tmp := MyFunc( In1:=x2, In2:=x3 );

out := MyFunc( In1:=x1, In2:=tmp );

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Precautions for Correct Use

The order of priority for operators is sometimes different for different standards and manufactur-

ers. Special attention is necessary for the priority of exponent operators. We therefore recom-

mend that you use parentheses to ensure that calculations are performed in the intended order.

Example: For X:= -2**3**4; we recommend that you use the following expression:

X:= ((-2)**3)**4;.

Additional Information

Calculations are performed based on the data types. For example, the result of calculations with

integer data will be integer data. Therefore, if the expression A/B is calculated with INT variables

A = 3 and B = 2, the result would not be 1.5 because all values after the decimal point are trun-

cated. In this case, the expression (A/B)*2 would evaluate to 2 instead of 3.

Data Types for Operator Operands

If all the operands for an operator have the same data type, any data type given as “Supported” in

the following table can be set as operands. However, if an operand with a different data type is set

for the operator, an implicit cast is required. Refer to Implicit Casts on page 6-127 for details on

implicit casting.

Argu-

Compar-

Posi-

Assign-

Numeric

Modulo-

Equality

Logic

ment

Power

ison

tive/neg-

ment

opera-

division

opera-

setting

operator

opera-

ative

operator

tors

operator

tors

operator

tors

signs

Data type

NOT

AND

−

MOD

−

XOR

Boolean

---

Bit string

---

Integer

OK^*1

---

Real number

---

Duration

---

Date

---

Time of day

---

Date and

---

time

Text string

---

---^*2

---

Enumeration

---

Structure par-

---

ent

Array parent

---

OK: Possible

---: A building error will occur.

Integer variables are calculated as real number variables even if they set as operands. If a rounding error is

included in the result of calculations, the result may not be an intended value because all values after the dec-

imal point are truncated. Use the EXPT and TO_** (Integer Conversion Group) instructions together to round

values after the decimal point.

Example: TO_INT(EXPT(X,Y))

Do not use operators to compare text string variables. Use instructions (such as EQascii) instead.

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ST Language Statements

Assignment

Overview:

This statement assigns the right side (i.e., the value of the expression) to the left side (i.e., the vari-

able).

Reserved Words:

Combination of a colon (:) and an equals sign (=)

Statement Structure:

<variable>:=<expression>;

<variable>:=<variable>;

<variable>:=<constant>;

Application:

Use this statement to assign a value to a variable. For example, use it to set initial values or to store

the results of a calculation.

Description:

This statement assigns (or stores) the <expression_value> to the <variable>.

Example:

Example 1: The following statement assigns the result of the expression X+1 to variable A.

A:=X+1;

Example 2: The following statement assigns the value of variable B to variable A.

A:=B;

Example 3: The following statement assigns a value of 10 to variable A.

A:=10;

Precautions:

• Either the source data type must match the destination data type, or the combination of data types

must allow implicit casting. A building error will occur if you do not use this notation.

• If the value that is assigned is STRING data, make the size of the destination STRING variable

larger than that of the source string. Otherwise, an error will occur.

• For STRING variables, assignment is allowed if the size of left-hand variable is greater than the

size of the text string stored in right-hand variable.

Example:

Assignment is allowed in the following case.

• Variable Table:

Variable

Data type

Size

name

Var1

STRING

Var2

STRING

• User Program:

Var2 :='ABC';

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Var1 := Var2;

You cannot make assignments to union variables. You must make the assignments to individual

members of the unions.

RETURN

Overview:

The following actions occur depending on where the ST statement is used.

The ST program is ended during operation and the next program is executed.

ST in a Function Inside a Function Block Instance

The function or function block is ended during operation and the next instruction after the calling

instruction is executed.

Inline ST

The POU that contains inline ST with a RETURN statement is ended.

Reserved Words:

RETURN

Statement Structure:

RETURN;

Application:

Use this statement to force the current program, function, or function block to end.

IF with One Condition

Overview:

The construct executes the specified statement when a condition is met. If the condition is not met,

another statement is executed. The following expressions are used to specify whether the condition

is met.

TRUE: The condition is met.

FALSE: The condition is not met.

Reserved Words:

IF, THEN, (ELSE), END_IF

Note You can omit ELSE.

Construct Structure:

IF <condition_expression> THEN

<statement_1>;

ELSE

<statement_2>;

END_IF;

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Process Flow Diagram:

Condition

FALSE

expression

TRUE

Statement 1

Statement 2

Application:

Use this construct to perform one of two processes depending on evaluation of a condition (condi-

tion expression).

Description:

If <condition_expression> is TRUE, <statement_1> is executed.

If <condition_expression> is FALSE, <statement_2> is executed.

Precautions:

• IF must always be used together with END_IF.

• Write a statement that evaluates to TRUE or FALSE (for example IF A>10) or a BOOL variable

(for example IF A) for the condition expression.

• You can write <statement_1> and <statement_2> on multiple lines. Separate statements with a

semicolon (;).

Example: Another IF Statement before <statement_1>

IF <condition_expression_1> THEN

IF <condition_expression_2> THEN

<statement_1>;

ELSE

<statement_2>;

END_IF;

Process Flow Diagram:

Condition

FALSE

expression 1

TRUE

Condition

FALSE

expression 2

TRUE

Statement 1

Statement 2

ELSE corresponds to the previous THEN statement, as shown above.

• You can execute more than one statement for both <statement_1> and <statement_2>. Separate

statements with a semicolon (;).

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• You can omit the ELSE statement. If it is omitted, nothing is executed when <condition_expres-

sion> is FALSE.

Process Flow Diagram:

FALSE

Condition

TRUE

Statement

Example:

Example 1: A value of 10 is assigned to variable X when the statement A > 0 is TRUE. A value

of 0 is assigned to variable X when the statement A > 0 is FALSE.

IF A>0 THEN

X:=10;

ELSE

X:=0;

END_IF;

Example 2: A value of 10 is assigned to variable X and a value of 20 is assigned to variable Y

when the statements A > 0 and B > 1 are both TRUE. A value of 0 is assigned to

variable X and variable Y when the statements A > 0 and B > 1 are both FALSE.

IF A>0 AND B>1 THEN

X:=10;Y:=20;

ELSE

X:=0;Y:=0;

END_IF;

Example 3: A value of 10 is assigned to variable X when the BOOL variable A is TRUE. A value

of 0 is assigned to variable X when variable A is FALSE.

IF A THEN X:=10;

ELSE X:=0;

END_IF;

IF with Multiple Conditions

Overview:

The construct executes the specified statement when a condition is met. If a condition is not met but

another condition is met, another statement is executed. If neither condition is met, another state-

ment is executed.

The following expressions are used to specify whether the condition is met.

TRUE: The condition is met.

FALSE: The condition is not met.

Reserved Words:

IF, THEN, ELSIF, (ELSE), END_IF

Note You can omit ELSE.

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Application:

Use this construct to perform a process depending on evaluation of multiple conditions (condition

expressions).

Description:

If <condition_expression_1> is TRUE, <statement_1> is executed.

<condition_expression_1> is FALSE and

<condition_expression_2> is TRUE, then

<statement_2> is executed.

<condition_expression_2> is FALSE and

<condition_expression_3> is TRUE, then

<statement_3> is executed.

If <condition_expression_n> is TRUE, <statement_n> is executed.

If none of the conditions is TRUE, <statement_m> is executed.

Precautions:

• IF must always be used together with END_IF.

• Write statements that can be TRUE or FALSE for the condition expressions. Example: IF(A>10)

You can also specify BOOL variables (including functions that return a BOOL value) for the condi-

tion expressions instead of an actual expression. In that case, when the variable is TRUE, the

evaluated result is TRUE and when the variable is FALSE, evaluated result is FALSE.

• You can write any of the statements on multiple lines. Separate statements with a semicolon (;).

• You can omit the ELSE statement. If it is omitted, and none of the conditions produces a match,

nothing is done.

Example:

A value of 10 is assigned to variable X when the statement A > 0 is TRUE.

A value of 1 is assigned to variable X when the statement A > 0 is FALSE and statement B = 1 is

TRUE.

A value of 2 is assigned to variable X when the statement A > 0 is FALSE and statement B = 2 is

TRUE.

If none of the conditions is TRUE, a value of 0 is assigned to the variable X.

IF A>0 THEN X:=10;

ELSIF B=1 THEN X:=1;

ELSIF B=2 THEN X:=2;

ELSE X:=0;

END_IF;

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z CASE

Overview:

This construct executes a statement that corresponds to an integer set value that matches the value

of an integer expression.

Reserved Words:

CASE

Construct Structure:

CASE <integer_expression> OF

<integer_expression_value_1>:<statement_1>;

<integer_expression_value_2>:<statement_2>;

<integer_expression_value_n>:<statement_n>;

ELSE<statement_m>;

END_CASE;

Process Flow Diagram:

Equal to

Yes

value 1?

Yes

Equal to

value 2?

Yes

Equal to

value n?

Statement m

Statement n

Statement 2

Statement 1

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6 Programming

Application:

Use this construct to perform different actions based on the value of an integer.

Description:

If <integer_expression> matches <integer_expression_value_n>, <statement_n> is executed.

If <integer_expression> does not match any of the integer values, <statement_m> is executed.

Precautions:

•

CASE must always be used together with END_CASE.

•

Use one of the following for the <integer_expression>:

• An integer or enumeration variable (example: abc)

• An integer expression (example abc+def)

• A function that returns an integer value (example: xyz())

•

You can write any of the statements on multiple lines. Separate statements with a semicolon (;).

•

To specify OR logic of multiple integers for <integer_expression_value_n>, separate the values

with commas. To specify a continuous range of integers, separate the start integer and the end

integer with two periods (..).

Example 1: You can specify a condition for a specific integer value, or the same condition for

multiple integer values.

CASE A OF

1: X:=1;

A value of 1 is assigned to variable X when variable A is 1.

2: X:=2;

A value of 2 is assigned to variable X when variable A is 2.

3: X:=3;

A value of 3 is assigned to variable X when variable A is 3.

ELSE

If none of the values is matched, a value of 0 is assigned to

X:=0;

the variable X.

END_CASE;

CASE A OF

1: X:=1;

A value of 1 is assigned to variable X when variable A is 1.

2,5: X:=2;

A value of 2 is assigned to variable X when variable A is 2 or 5.

6..10: X:=3;

A value of 3 is assigned to variable X when variable A is between 6 and 10.

A value of 4 is assigned to variable X when variable A is 11, 12,

11,12,15..20: X:=4;

or between 15 and 20.

ELSE

X:=0;

If none of the values is matched, a value of 0 is assigned to the

END_CASE;

variable X.

Example 2: You can give an integer variable, integer expression, integer function return value,

enumeration variable, or enumeration function return value for the <integer_expres-

sion>. An example is shown below.

• Example for an Integer Enumeration Variable

CASE ColorVar OF

RED:

X := 0;

BLUE:

X := 1;

ELSE

X := 2;

END_CASE;

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• Example for an Integer Expression

CASE (a1 + a2) OF

X := 0;

X := 1;

ELSE

X := 2;

END_CASE;

• Example of an Integer Enumeration Function Return Value

CASE FUN( ) OF

Branches depending on the return value of FUN( ).

X := 10;

X := 11;

ELSE

X := 12;

END_CASE;

Data Types That You Can Use in CASE Constructs

Classification

Data type

<integer_expression>

Integers

Supported.

Basic data types

Boolean, bit string, real, duration, date, time

Not supported.

of day, date and time, or text string data

Arrays

Not supported.

Data type specifica-

Array specifications

Supported for integers and enu-

tions

Elements

merations only.

Structures

Not supported.

Structures

Supported for integers and enu-

Members

merations only.

Derivative data types

Unions

Not supported.

Unions

Supported for integers and enu-

Members

merations only.

Enumerations

Supported.

FOR

Overview:

This construct repeatedly executes the same statements until a variable (called the FOR variable)

changes from one value to another value.

The following expressions are used to specify whether the condition is met.

TRUE: The condition is met.

FALSE: The condition is not met.

Reserved Words:

FOR, TO, (BY), DO, END_FOR

Note You can omit BY.

Construct Structure:

FOR <FOR_variable>:= <initial_value> TO <end_value> BY <increment/decrement> DO

<statement>;

END_FOR;

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Process Flow Diagram:

FOR variable = Initial value

TRUE

FOR variable >

end value?

Repeated

FALSE

Statement

FOR variable +

Increment/decrement value

End

Application:

Use this construct when you know in advance how many times you want to repeat a process.

This type of repeat construct is particularly effective to specify each element of an array variable

based on the value of a FOR variable.

Description:

A decision is made based on the evaluation of <initial_value>, <end_value>, and <increment/decre-

ment>.

When <FOR_variable> is <initial_value>, <statement> is executed.

After execution, the value of <increment/decrement> is added to <FOR_variable> and <statement>

is executed again if <FOR_variable> is less than the value of the <end_value>.

After execution, the value of <increment/decrement> is added to <FOR_variable> and <statement>

is executed again if <FOR_variable> is less than the value of the <end_value>.

This process is repeated.

The loop ends when <FOR_variable> > <end_value>.

If <increment/decrement> is negative, the directions of the comparison symbols in the above state-

ments are reversed.

Precautions:

• If the FOR variable is signed, <increment/decrement> can be a negative number.

• FOR must always be used together with END_FOR.

• The FOR variable becomes the end value plus increment/decrement after execution of the pro-

cess is completed for the end value. This ends the FOR construct.

Example: When the FOR construct is completed in the following ST statements, the value of i is

101.

FOR i:=0 TO 100 DO

X[i]:=0;

END_FOR;

// Here, i is 101.

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•

Do not write code that directly modifies the FOR variable inside the FOR construct. Unintended

operation may result.

Example:

FOR i:=0 TO 100 BY 1 DO

X[i]:=0;

i:=i+INT#5;

END_FOR;

•

You can write any of the statements on multiple lines. Separate statements with a semicolon (;).

•

You can omit BY<increment/decrement>. If it is omitted, the statement is executed with an incre-

ment value of 1.

•

You can specify an integer (SINT, INT, DINT, LINT, USINT, UINT, UDINT, or ULINT) variable or

integer value for the <initial_value>,<end_value>, and <increment/decrement>. You can also

specify a function that returns an integer value.

Example 1: A value of 100 is assigned to array variable elements SP[n]. The FOR variable is

variable n, the initial value is 0, the end value is 50, and the increment is 5.

FOR n := 0 TO 50 BY 5 DO

SP[n] := 100;

END_FOR;

Example 2: The total of elements DATA[1] through DATA[50] of array variable elements DATA[n]

is calculated and the result is assigned to the variable SUM.

IF a THEN

FOR n := 0 TO 50 BY 1 DO

DATA[n]:= 1 ;

END_FOR;

FOR n := 0 TO 50 BY 1 DO

SUM:= SUM + DATA[n] ;

END_FOR;

a:=FALSE;

END_IF;

Example 3: The maximum and minimum values of elements DATA[1] through DATA[50] of array

variable elements DATA[n] are found. The maximum value is assigned to the MAX

variable, and the minimum value is to the MIN variable. The value of DATA[n] is

from 0 to 1,000.

MAX :=0;

MIN :=1000;

FOR n :=1 TO 50 BY 1 DO

IF DATA[n] > MAX THEN

MAX :=DATA[n];

END_IF;

IF DATA[n] < MAX THEN

MIN :=DATA[n];

END_IF;

END_FOR;

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•

If the total execution time of the statements in the FOR construct from when the FOR variable is

incremented/decremented from the initial value until it reaches the end value exceeds the task

period, a Task Period Exceeded error occurs.

• When the FOR Variable Cannot Logically Reach the End Value

Example:

FOR i := 0 TO 100 BY 1 DO

intArray[i] := i;

:= INT#50;

An infinite loop occurs and results in a Task

END_FOR;

Period Exceeded error.

Example:

FOR i := 0 TO 100 BY 0 DO

An infinite loop occurs and results in a Task

;

Period Exceeded error.

END_FOR;

• When an Overflow or Underflow Occurs Because the FOR Variable Exceeds the End Value

Example:

FOR i := 0 TO 254 BY 2 DO

INTArray[i] := i;

END_FOR;

Additional Information

You can specify arithmetic expressions for <end_value> and <increment/decrement>.

However, the evaluation is performed for <end_value> or <increment/decrement> only before

the execution of FOR loop operation. The values of <end_value> and <increment/decrement>

do not change after the FOR loop operation is started.

For example, in the following case, the value of <end_value> is 10 and <increment/decrement>

3. Even after the FOR loop operation is started and the values of variable A and C are

changed, the value of <end_value> is still 10 and <increment/decrement> is still 3.

A := INT#1;

B := INT#2;

C := INT#10;

FOR i := 0 TO C BY A+B DO

INTArray[i] := i;

A := B + i;

C := C + i;

END_FOR;

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6 Programming

Data Types That You Can Use in FOR Constructs

<FOR_variable>, <initial_value>,

Classification

Data type

<end_value>, and <increment

/decrement>^*1

Boolean, bit string, real, duration, date,

Not supported.

time of day, date and time, or text string

Basic data types

data

Integers

Supported.

Arrays

Not supported.

Data type specifica-

Array specifications

Supported for integers and enumera-

tions

Elements

tions only.^*2

Structures

Not supported.

Structures

Supported for integers and enumera-

Members

tions only.^*2

Derivative data types

Unions

Not supported.

Unions

Members

Not supported.

Enumerations

Supported.*2

You must use the same data type for the <FOR_variable>, <end_value> and <increment/decrement>. Other-

wise, an error occurs when the program is built on the Sysmac Studio.

You cannot use enumerations for <FOR_variable>, <end_value> and <increment/decrement>.

WHILE

Overview:

This construct repeatedly executes the specified statements as long as a condition expression is

TRUE.

Reserved Words:

WHILE, DO, END_WHILE

Construct Structure:

WHILE <condition_expression> DO

<statement>;

END_WHILE;

Process Flow Diagram:

Repeated

Condition

FALSE

expression

TRUE

Statement

End

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6 Programming

Application:

Use this type of repeat construct when you do not know how many times to repeat a process (i.e.,

when you do not know how many times based on the condition) and you want to repeat a process

for as long as a certain condition is met. You can also use this type of repeat construct to execute a

process only when a condition expression is TRUE (pre-evaluation repeat construct).

Description:

The <condition_expression> is evaluated before <statement> is executed.

<condition_expression> is TRUE, <statement> is executed. Then the <condition_expression> is

evaluated again. This process is repeated.

If the <condition_expression> is FALSE, <statement> is not executed and the <condition_expres-

sion> is no longer evaluated.

Precautions:

•

WHILE must always be used together with END_WHILE.

•

If the <condition_expression> is FALSE before <statement> is executed, the WHILE construct is

exited and <statement> is not executed.

•

You can write <statement_1> and <statement_2> on multiple lines. Separate statements with a

semicolon (;).

•

You can execute more than one statement for <statement>. Separate statements with a semicolon (;).

•

You can also specify a BOOL variable (including functions that return a BOOL value) for the con-

dition expressions instead of an actual expression.

Example:

Example 1: The first multiple of 7 that exceeds 1,000 is calculated and assigned to variable A.

A := 0;

WHILE A <= 1000 DO

A := A+INT#7;

END_WHILE;

Example 2: The value of variable X is doubled if X is less than 3,000 and the value is assigned

to array variable element DATA[1]. Next, the value of X is doubled again and the

value is assigned to the array variable element DATA[2]. This process is repeated.

n := 1;

X := 1;

WHILE X < 3000 DO

X:= X*INT#10#2;

DATA[n]:= X;

n := n+INT#1;

END_WHILE;

•

If you do not write correct condition expressions, the program execution time increases and may

cause a Task Period Exceeded error.

Example:

boolVar := TRUE;

WHILE boolVar DO

intVar := intVar + INT#1;

END_WHILE;

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6 Programming

z REPEAT

The following expressions are used to specify whether the condition is met.

TRUE: The condition is met.

FALSE: The condition is not met.

Overview:

This construct repeatedly executes one or more statements until a condition expression is TRUE.

Reserved Words:

REPEAT, UNTIL, END_ REPEAT

Construct Structure:

REPEAT

<statement>;

UNTIL <condition_expression>

END_REPEAT;

Process Flow Diagram:

Statement

Repeated

Condition

FALSE

expression

TRUE

End

Application:

Use this type of repeat construct when you do not know how many times to repeat a process (i.e.,

when you do not know how many times based on the condition) and you want to repeat a process

for as long as a certain condition is met after processing. Use this type of repeat construct to deter-

mine repeat execution based on the result of the execution of a process (post-evaluation repeat

construct).

Description:

First, <statement> is executed unconditionally. Then the <condition_expression> is evaluated.

If <condition_expression> is FALSE, <statement> is executed.

<condition_expression> is TRUE, <statement> is not executed and the REPEAT construct is

exited.

Precautions:

• REPEAT must always be used together with END_REPEAT.

• Even if the <condition_expression> is TRUE before <statement> is executed, <statement> is exe-

cuted.

In other words, <statement> is always executed at least one time.

•

<statement> can contain multiple lines of code for the statement. Separate statements with a

semicolon (;).

• You can also specify a BOOL variable (including functions that return a BOOL value) for the con-

dition expressions instead of an actual expression.

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6 Programming

EXIT

Overview:

Use this statement only inside a repeat construct (FOR construct, WHILE construct, or REPEAT

construct) to exit the repeat construct.

Use this statement inside an IF construct to exit from the repeat construct when a condition is met.

Reserved Words:

EXIT

Construct Structure (e.g., in an IF Construct):

FOR (WHILE, REPEAT) <statement>

IF <condition_expression> THEN EXIT;

END_IF;

END_FOR (WHILE, REPEAT);

Application:

Use EXIT to end a repeating process before the end condition is met.

Description (e.g., in an IF Construct):

If the <condition_expression> is TRUE, the repeat construct (FOR construct, WHILE construct, or

REPEAT construct) is ended and all code inside the repeat construct after the EXIT statement is

ignored.

Note 1

You can also specify a BOOL variable instead of an expression for the condition expressions.

Even if the <condition_expression> is TRUE before <statement> is executed, <statement> is executed.

Example:

Variable n is repeatedly incremented by 1 from 1 to 50 while the value of n is added to array vari-

able elements DATA[n]. However, if DATA[n] exceeds 100, the repeat construct is exited.

IF A THEN

DATA[3] :=98;

FOR n := 1; TO 50 BY 1 DO

DATA[n] := DATA[n] + n;

IF DATA[n] > 100 THEN EXIT;

END_IF;

END_FOR;

A :=FALSE;

END_IF;

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6 Programming

Function Block Calls

Overview:

This statement calls a function block.

Reserved Words: None

Statement Structure:

Give the argument specifications (to pass the values of the specified variables to the input variables

of the called function block) and the return value specification (to specify the variable that will

receive the value of the output variable of the called function block) in parenthesis after the instance

name of the function block. There are two methods of writing this statement, as shown in (1) and (2)

below. We recommend method 1 for program readability.

Notation Method 1:

Give both the variable names of the called function block and the parameter names of the calling POU.

ABC(A:=x1, B:=x2, C=>y1);

ABC: Function block instance name

A and B: Input or in-out variable names of called function block

x1 and x2: Input or in-out parameter of calling POU (can be a constant)

C: Output variable of called function block

y1: Output parameter of calling POU

• Ladder Diagram Expression

ABC

MyFB

• You can give the arguments and return values in any order.

• You can omit the input variable names and input parameter names. If you omit these names, the

values assigned to the input variables for the previous call are assigned to the input variables

again. If this is the first time that the function block is called, the input variables are set to their ini-

tial values.

• You can omit the output variables and output parameters. If they are omitted, the value of the out-

put variable is not assigned to anything.

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6 Programming

Notation Method 2:

Omit the variable names of the called function block and give the parameter names of the calling

POU.

ABC(x1, x2, y1);

ABC: Function block instance name

A and B: Omitted. (Input or in-out variable of called function block)

x1 and x2: Input or in-out parameter of calling POU (can be a constant)

C: Omitted. (Output variable of called function block or constant)

y1: Output parameter of calling POU

• Ladder Diagram Expression

ABC

MyFB

• The order of parameters is based on the function block definition. The order is the same as the

local variable definition for the function block, from top to bottom.

Application:

This statement calls a function block.

Example

• Programming

Notation 1

ChangeFixToFloat(Execute:=Exe,Data32_1:=FixPointData1, Data32_2:=FixPointData2,

NoOfDigit_1:=FixPointPos1,

NoOfDigit_2:=FixPointPos2,OK=>Done,Double_1=>RealData1,

Double_2=>RealData2);

Notation 2

ChangeFixToFloat(Exe, FixPointData1, FixPointData2, FixPointPos1, FixPointPos2,

Done, RealData1, RealData2);

• Ladder Diagram Expression

ChangeFixToFloat

Exe

ConvData32ToDouble

Done

Execute

FixPointData1

Data32_1

Double_1

RealData1

FixPointData2

Data32_2

Double_2

RealData2

FixPointPos1

NoOfDigit_1

FixPointPos2

NoOfDigit_2

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Omron IPC Machine Controller Industrial Panel PC / Industrial Box PC. Software User’s Manual (Industrial PC Platform NY-series) - page 10