Rockwell Automation 57C610 Enhanced Basic Language, AutoMax User Manual

Page 54

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6Ć14

where:

variable = simple numeric variable known as the loop index.
expression_1 = initial value of the index; can be any

numeric expression.

expression_2 = terminating condition; can be any

numeric expression.

expression_3 = incremental value of the index; the STEP size

is optional. If specified, it can be positive or

negative; if not specified, the default is +1.

Expression_3 can be any numeric expression.

The NEXT statement has the following format:

NEXT variable

where:

variable = same variable named in the corresponding FOR

statement

The FOR and NEXT statements must be used together. You cannot

use one without the other. If you do, the program cannot be

compiled. The FOR statement defines the beginning of the loop; the

NEXT statement defines the end. Place the statements you want

repeated between the FOR and NEXT statements. You are actually

building a counter in your program to determine the number of

times the loop is to execute when you use FOR and NEXT.
Here is a simple FORĆNEXT statement example:

20 FOR M% = 30 TO 90 STEP 3
30...
40...
50 NEXT M%

M% is given the initial value of 30, and BASIC tests to determine if

M% is less than or equal to the terminating value of 90. The loop is

executed because M% is less than 90. When the NEXT statement is

encountered, the value of M% is incremented by 3. BASIC goes

back to line 20 and tests again to see if M% is greater than 90. When

BASIC reaches the NEXT statement and M% has a value of 87,

BASIC adds 3 to M% and tests the result against the terminating

value. The result, 90, is not greater than the terminating value of 90,

so BASIC executes the loop again. When BASIC reaches the NEXT

statement again, it adds 3 to M%, producing 93. Because this is

greater than the terminating value, BASIC terminates the loop by

transferring control to the next sequential statement after the NEXT

statement.
The following program will print the numbers 1 through 11 as shown

below the program listing:

10 FOR I% = 1 TO 10
20 PRINT I%
30 NEXT I%
40 PRINT I%
50 END
1
2
3

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