Rockwell Automation 1398-PDM-xxx IQ Master Version 3.2.4 for IA-2000 and IQ-5000 Positioning Drive Modules, IQ-55 - Manual (Page 166)

144 IQ Programming Structure • Program Structure Instructions
Publication 1398-PM601A-EN-P — October 2000
TUTORIAL
When a CALL statement is executed, execution is transferred to the first line of the subroutine. The sub-
routine is executed until a RETURN statement is executed. When the RETURN is executed, program
execution returns to the program line in the main program following the CALL. Subroutines may con-
tain more that one RETURN statement.
Subroutines may not be nested. Only the main body of the program may contain a CALL to a subrou-
tine. Refer to Part 5
•
Language Reference for more detailed information on the SUB, CALL and
RETURN statements. The following flowchart and code segment illustrate the use of subroutines.
IF Structure
The IF statement is used to execute an instruction or a block of instructions one time if a condition is
true. The simplified syntax for the IF instruction is:
IF condition
{
…
conditional statements
}
Refer to Part 5
•
Language Reference for more detailed information. The following flowchart and code
segment illustrate the use of the IF instruction.
…
statements
CALL UpdateDisplay
O2 = ON
…
statements
SUB UpdateDisplay
V1 = POS1
V2 = FE
V3 = POSN
PRINT 1,1, V1
PRINT 2,1, V2
PRINT 3,1, V3
RETURN
…
statements
If I1 = ON
{
O2 = OFF
MOVD = 3
}
…
statements
Start Subroutine
UpdateDisplay
Position to Display
Following Error to Display
Feedback Position to Display
Return
Start
Call UpdateDisplay
Output 2 ON
End
Is input 1 ON?
Start
Yes
No
Output 2 OFF
Move Distance 3 inches
End
Output 2 ON
Move Distance 4 inches