Mitsubishi Electric MELSEC iQ-F Series - Page 109

8 SFC PROGRAM
8.5 SFC Program Execution Order
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8
Continuous transition ON/OFF operation
The transition conditions for the SFC program include "With continuous transition," "With continuous transition (operation
compatible with FX3)" and "Without continuous transition."
The setting "With continuous transition" or "Without continuous transition" is determined by "FX3 Compatible Transition
Operation Mode Setting" and SM323 (presence/absence of continuous transition for entire block).
• The tact time can be reduced by setting the condition to "Continuous transition" or "Continuous transition
(operation compatible with FX3)." Accordingly, the wait time from when the transition becomes TRUE until
the action of the destination step is executed can be eliminated. However, the setting to "Continuous
transition" or "Continuous transition (operation compatible with FX3)" may slow down the operation of other
blocks and sequence programs.
• SM324 (Continuous transition disable flag) is turned off only when "Continuous transition" is set. (Because
the system is basically turned on automatically when the SFC program is executed, SM324 is always ON.
Also, when "Continuous transition" (FX3 compatible operation) is set, SM324 is always ON.) Therefore,
continuous transition can be prohibited by using SM324 as a transition condition.
• When "FX3 Compatible Transition Operation Mode Setting" is valid, "Continuous transition (operation
compatible with FX3)" is enabled regardless of whether SM323 is on or off.
FX3 compatible transition
operation mode setting
SM323 Description
Disable OFF No continuous
transition
When the transition becomes TRUE, the action of the transition destination step is
executed in the next scan.
ON Continuous
transition
When the transition becomes TRUE, the action of the transition destination step is
executed within the same scan.
When the transitions of the steps become TRUE continuously, the actions are executed
within the same scan until the transition becomes FALSE or the end step is reached. The
action of the transition source step is executed in the contact OFF status in a scan in
which the transition becomes TRUE.
Enable ON/OFF With continuous
transition (operation
compatible with
FX3)
When the transition becomes TRUE, the action of the transition destination step is
executed within the same scan.
When the transitions of the steps become TRUE continuously, the actions are executed
within the same scan until the transition becomes FALSE or the end step is reached.
Unlike normal continuous transitions, the action of the destination step is executed in the
contact OFF status in the next scan where the transition becomes TRUE.