Sfc Program Processing Sequence - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

SFC program processing sequence

Block execution sequence
While the SFC program is running, the actions of each step are executed sequentially starting from the initial step of an active
block.
An SFC program containing multiple blocks checks the state (active/inactive) of the blocks in ascending order of block
numbers(block 0  block 1  block 2).
An active block executes the actions of active steps in the block.
An inactive block checks for existence of a start request. If a start request exists, the block is activated and the active steps in
the block are executed.
(1)
BL0
(2)
Only block 0 can be started automatically when the block 0 autostart is specified in the start condition setting of the SFC
setting. With this setting, even when block 0 reaches the end step and becomes inactive, it is started again in the next scan.
( Page 132 Start condition setting)
A request for END, PAUSE, RESTART of a block is processed immediately before execution processing in the block.
8 SFC PROGRAM
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8.6 SFC Program Execution Order
(3)
BL1
(4)
Processing is performed in the following order.
(5)
(1) Processing of block 0 (BL0)
(2) Execution of the step in block 0 (BL0)
(3) Processing of block 1 (BL1)
(4) Execution of the initial step of block 1 (BL1)
(5) Processing of the next block