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

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).
• 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
• When the corresponding block is stopped, the stop timing is as described below.
Setting of Operation
Output Mode Output at
at Block Stop Block Stop
in PLC (SM325)
Parameter
Turns OFF OFF
(coil output OFF) (coil output OFF)
Remains ON
(coil output held)
Remains ON ON
(coil output held) (coil output held)
*1 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.
4 SFC PROGRAM CONFIGURATION
112
4.5 SFC Information Devices
Stop timing
• 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.
Status of Operation
STOP-time
Active step other than held
Mode Bit
step (including HOLD step
whose transition condition is
not satisfied)
OFF or no • Immediately after a STOP request
setting is made, the coil output of the
(immediate operation output is turned OFF and
stop) the block is stopped.
• The status remains active.
ON • Normal operation is performed until
(STOP after the transition condition is satisfied.
transition) • 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.
OFF or no • Immediately after a STOP request
setting is made, the block is stopped with
(immediate the coil output of the operation
stop) output being held.
• The status remains active.
ON • Normal operation is performed until
(STOP after the transition condition is satisfied.
transition) • 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.
*1
Held step
Coil HOLD Operation HOLD
step (SC) step (without
transition
check) (SE)
• Immediately • Immediately after a STOP request is
after a STOP made, the coil output of the operation
request is output is turned OFF and the block is
made, the coil stopped.
output of the • The status remains active.
operation
output is
turned OFF
and the 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)