Omron SYSMAC CX-Programmer 8.1, Operation Manual

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Precautions When Creating SFC Programs Section 1-5
34
Example:
N Step 1 Action1
Action1
When step 1 has become inactive, action flag Action1.Q goes OFF, the action flag
(Action1.Q) becomes FALSE, and the output goes OFF.
1-5-2 Action Program Precautions
Action Program Execution Sequence
The order of execution for the actions in multiple steps that become active
simultaneously within the same SFC execution cycle is as follows:
1. Bits and Boolean variables
2. Action
programs
If multiple action programs become active, they are each executed once each
cycle from top down according to their position in the action program tree in the
workspace.
Example 1
The execution order for multiple action programs registered in a single step is not
according to the order of the action programs next to the step, but rather in the order
the action programs are arranged in the workspace.
Note: If more than one bit or Boolean variable is registered in an action, they are executed in
the order that they are registered in the action block.
Action program
execution order
(1)
(2)
(3)
(4)
(5)
Action execution order
Action program
Action program
Action program
Bit or Boolean variable
Bit or Boolean variable
First bits CIO 10.01 (1) and CIO 10.02 (2) are
executed (i.e., turned ON), and then the action
programs are executed in the following order:
Action 2 (3), Action 1 (4), and Action 3 (5).
Type of action
Example 2
The execution order for actions in steps that simultaneously become active (e.g., steps
3 and 4) is not by step, but rather bits and Boolean variables are executed first and
then action programs.
Note: If more than one bit or Boolean variable is registered in an action, they are executed in
the order that they are registered in the action block.