Precautions When Creating Sfc Programs; Holding Or Resetting An Action's Outputs - Omron WS02-CXPC1-V8 - V8.1 REV 02-2009 Operation Manual

Precautions When Creating SFC Programs

1-5

Precautions When Creating SFC Programs

1-5-1

Holding or Resetting an Action's Outputs

The action's type determines whether the action's outputs (see note) are held or reset
when the step goes from active to inactive status.
Note: In this section, the term "output" refers to the following.
Bit Specification
• The output is reset when a holding action qualifier (S) is not specified, but a qualifier
such as action qualifier (N) is specified.
• When a holding action qualifier (S) is specified, the output is held by the action
qualifier's execution condition even if the step becomes inactive. In this case, the
output can be reset by using a resetting action qualifier (R) and adding a step, as
shown in the following chart.
Ladder Program
With the default setting, the outputs are reset.
If you want to retain the output status, deselect the ladder program's Reset Output at
Final Scan Option (remove the check mark).
Note 1. When timer instructions are being used and outputs are set to be held (not reset), the
ST Program
With the default setting, the outputs are held.
If you want to reset the outputs, reset the outputs by including an "Action flag = FALSE"
condition (see note) in a statement such as an IF statement.
Note: The action flag is ON when the step is active, and OFF when the step is inactive. The flag
• For a bit specification, it refers to the specified bit address value in memory.
• For a ladder program, it refers to the value written in memory by an instruction.
• For an ST program, it refers to the value written in memory by a statement.
Step 1 S Output
Step 2 R Output
Timer Completion Flags will also be held, and the next time that the same action is
executed, it will start execution with the Timer Completion Flag ON. If you want to reset
the timer Completion Flags separately, include the action flag (see note 2) in the timer
instruction's input condition by ANDing the flag as a NO condition to reset the timer.
2. The action flag is ON when the step is active, and OFF when the step is inactive.
The flag is written as Action_Name.Q. For details on action flags, refer to the explanation
of Flags Used to Monitor a Step's Active Status in 2-3 Elements of SFC.
is written as Action_Name.Q. For details on action flags, refer to the explanation of Flags
Used to Monitor a Step's Active Status in 2-3 Elements of SFC.
Output: Boolean variable
Section 1-5
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