Mitsubishi MELSEC-Q Series Programming Manual page 129

4 SFC PROGRAM CONFIGURATION
2) If the BRSET instruction is executed at an SFC program, block switching will be effective
only for the step currently being executed.
Even if the step in question is the same step, the BRSET instruction must be executed at
each block where the Sn and TRn instructions are used.
Moreover, within a single step, block switching will be effective from the point where the
BRSET instruction is executed to that step's processing END point.
When processing is repeated at the next scan following the processing END for that step,
the block in question will be designated as the "current block" until the point when the
BRSET instruction is executed again.
Sequence program
0
Execution
Program
Sn/TRn destination
block
Block 0
[Operation Error]
• Error No. 4621 occurs when the specified block does not exist or when the SFC program is in
the stand-by status.
[Program Examples]
(1) When X1 switches ON, the following program switches the Sn or TRn block number to the
block number stored at the D0 data register.
(2) When X2 switches ON, the following program switches the Sn or TRn block number according
to the constant at the Z1 index register.
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Sequence program
A END/0
END processing
not performed
Block specified
by instruction
The block No. (m) designated by BLm\Sn or
BLm\TRn becomes valid regardless of whether this instruction is
executed or not.
When multiple steps are active at parallel branch, etc., only the step
where the instruction was executed will be valid.
When it is desired to designate blocks at multiple steps, the instruction
must be executed at each step.
Condition
X1
X2
(Repeated)
B END Block "n"
END processing
not performed
Block specified
Current block
by instruction
1 scan
MOV Kn
BRSET D0
BRSET K0Z1
SFC program
Block "n+1"
Block specified
Current block
by instruction
D0
END
Block specified
by instruction
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