Allen-Bradley LOGIX 5000 Reference Manual page 529

Structured Text Programming
Affects Math Status Flags
No
Major/Minor Faults
None.
Examples
Example 1
IF...THEN
If performing this
IF rejects > 3 then
conveyor = off (0)
alarm = on (1)
Example 2
IF_THEN_ELSE
If performiing this
If conveyor direction contact = forward (1) then
light = off
Otherwise light = on
The [:=] tells the controller to clear light whenever the controller does the
following :
Enters the RUN mode.
Leaves the step of an SFC if you configure the SFC for Automatic reset. (This
applies only if you embed the assignment in the action of the step or use the action
to call a structured text routine via a JSR instruction.)
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Enter this structured text
IF rejects > 3 THEN
conveyor := 0;
alarm := 1;
END_IF;
Enter this structured text
IF conveyor_direction THEN
light := 0;
ELSE
light [:=] 1;
END_IF;
Chapter 10
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