Rockwell Automation 1398-PDM-xxx IQ Master Version 3.2.4 for IA-2000 and IQ-5000 Positioning Drive Modules, IQ-55 - Manual (Page 165)

IQ Programming Structure • Program Structure Instructions 143
Publication 1398-PM601A-EN-P — October 2000
TUTORIAL
} WHILE condition
Refer to Part 5
•
Language Reference for more detailed information. The following flowchart and code
segment illustrate the use of the DO/WHILE instruction.
WHILE Structure
This instruction is used if you want a block of code to execute while a condition is true. The difference
between the DO/WHILE instruction and the WHILE instruction is the WHILE instruction tests the con-
dition before any of the conditional statements are executed. If the condition is false when first tested,
the conditional statements are never executed. The syntax for the WHILE instruction is:
WHILE condition
{
…
conditional statements
}
Refer to Part 5
•
Language Reference for more detailed information. The following flowchart and code
segment illustrate the use of the WHILE instruction.
Subroutines
A subroutine is a group of IQ Basic instructions that is located at the end of the main body of the pro-
gram. It is marked by the SUB instruction at the top and a RETURN instruction at the end. The subrou-
tine is executed by using a CALL instruction in the main body of the program.
Subroutines are used if there is a procedure that needs to be done in several places in the program.
Rather than repeat those instructions at each location, a CALL to a subroutine that contains those
instructions may be used.
…
statements
DO
{
MOVD = 3
O1 = ON
DELAY = 2
} WHILE (I2 = ON)
…
statements
…
statements
WHILE (I2 = ON)
{
MOVD = 3
O1 = ON
DELAY 2
}
…
statements
Start
Move Distance 3 inches
Output 1 ON
Delay 2 seconds
End
Is Input 2 ON
Yes
No
Start
Move Distance 3 inches
Output 1 ON
Delay 2 seconds
End
Is Input 2 ON
Yes
No