Omron SYSMAC CX-Programmer 8.1, Руководство по эксплуатации

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Precautions When Creating SFC Programs Section 1-5
35
N 10.01
N Action2
N Action3
N 10.02
N Action1
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).
--(1)
--(3)
--(5)
--(2)
--(4)
(Action program tree in
workspace)
Action execution order
Step3 Step4
FALSE Trans2
Note
Refer to 2-2 Basic SFC Execution Cycle for information on the basic SFC execution
cycle, including the order of execution for action programs. Refer to 2-3-3 Action Blocks
for information on the execution of action blocks.
Final Scan
Final scan function is an action program execution method defined in the IEC 61131-3
standard. The CX-Programmer conforms to this IEC standard, and is equipped with the
final scan function.
The final scan function executes the action program just one more time after the
previously executed step becomes inactive, when programming switches to the next
step. This final scan function can be used to reset the outputs of the actions that were
executed.
Disabling the Final Scan Operation
The final scan function can be enabled and disabled with the following method. Select
Tools - Options from the menu, click the SFC Tab, select the Use Extended SFC
Settings Option, and select the Apply Final Scan Logic Option in the General Tab of the
SFC program’s properties.
Option selected: Final scan execution is enabled for that entire SFC program.
Option not selected: Final scan execution is disabled for that entire SFC program.
Programming Precautions When Passing Execution Results through a
Transition
When the final scan is enabled, the step action will be executed once in the next cycle
after the step changes from active to inactive status. Always use the following method
to write the action programs in the step before the transition to prevent the final scan
from affecting the results when calculation results, such as counter values, from an
action in the step before the transition are being evaluated in the step after the
transition.
Ladder Programming
Observe the following precautions if the Reset Output at Final Scan Option is
deselected (check mark removed) in the ladder program’s properties.
When a program section has a calculation that you do not want executed when the
step become inactive, always add the action flag as a NO condition for the calculation
by ANDing the flag in the execution condition for the calculation.
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 .