Structured Text Programming
534 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Important:
Do not iterate within the loop too many times in a single scan.
The controller does not execute any other statements in the routine until it completes
the loop.
A major fault occurs when completing the loop takes longer than the watchdog timer
for the task.
Consider using a different construct, such as IF_THEN.
Description
The syntax is:
The following diagrams illustrate how a WHILE_DO loop executes, and how an
EXIT statement leaves the loop early.
While the bool_expression is true, the controller
executes only the statements within the WHILE_DO loop.
To stop the loop before the conditions are true, use an EXIT
statement.
Affects Math Status Flags
No
Fault Conditions
A major fault will occur if Fault type Fault code
the construct loops too long 6 1
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