Block Stop Mode Bit - Mitsubishi MELSEC-Q Series Programming Manual

4 SFC PROGRAM CONFIGURATION

4.5.4 Block STOP mode bit

The block STOP mode bit setting determines when the specified block is stopped after the block
STOP/RESTART bit switches ON, or after a stop designation by the block STOP instruction
(PAUSE BLm).
(1) The stop timing for a block where a STOP request has occurred varies according to the
ON/OFF setting of the block STOP mode bit, as shown below.
Block STOP
mode bit
OFF
ON
(2) When the corresponding block is stopped, the stop timing is as described below.
Setting of
Operation
Status of
Output Mode at Output at
STOP-time
Block Stop
Block Stop in
Mode Bit
(SM325)
PLC Parameter
OFF or no
setting
(immediate
 Turns OFF
stop)
 OFF
(coil output
OFF) (coil
 Remains ON
output
ON
(coil output OFF)
(STOP after
held)
transition)
OFF or no
setting
(immediate
stop)
 ON
 Remains ON
(coil
(coil output
output
held) ON
held)
(STOP after
transition)
*: The held step indicates the step whose attribute has been set to the HOLD step (SC, SE, ST) and which is being held with the
transition condition satisfied.
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• The block is stopped immediately when the block STOP/RESTART bit switches from OFF
to ON, or when a block STOP instruction is executed. However, if the block
STOP/RESTART bit is switched ON within the current block, the STOP will occur when that
block is processed at the next scan, or when the instruction is executed.
• The block is stopped at the step transition which occurs when the transition condition for the
current step (active step) is satisfied. However, the operation output will not be executed for
the step following the transition.
• When multiple steps are active in a parallel branch, the STOP will occur sequentially at each
of the steps as their transition conditions are satisfied.
However, the held step stops immediately after a STOP request independently of the block
STOP mode.
Active step other than held step
(including HOLD step whose transition condition
is not satisfied)
 Immediately after a STOP request is made,
the coil output of the operation output is turned
OFF and the block is stopped.
 The status remains active.
 Normal operation is performed until the
transition condition is satisfied.
 When the transition condition is satisfied, the
end processing of the corresponding step is
performed.
At the same time, the transition destination
step becomes active and the block is stopped
before execution of the operation output.
 Immediately after a STOP request is made,
the block is stopped with the coil output of the
operation output being held.
 The status remains active.
 Normal operation is performed until the
transition condition is satisfied.
 When the transition condition is satisfied, the
end processing of the corresponding step is
performed.
At the same time, the transition destination
step becomes active and the block is stopped
before execution of the operation output.
Stop timing
Operation
Held step *
Operation HOLD
Coil HOLD step (SC) step (without
transition check) (SE)
 Immediately after a
STOP request is
 Immediately after a STOP request is
made, the coil
output of the made, the coil output of the operation
operation output is output is turned OFF and the block is
turned OFF and the stopped.
 The status remains active.
block is stopped.
 The status
becomes inactive.
 Immediately after a STOP request is made, the block is stopped
with the coil output of the operation output being held.
 The status remains active.
Operation HOLD
step (with transition
check) (ST)
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