Block Start Step (Without End Check) - Mitsubishi Q series Programming Manual

4 SFC PROGRAM CONFIGURATION

4.2.9 Block START step (without END check)

A block START step (without END check) is the step where the specified block is started, and if
the START destination block is active, the check of the transition condition to the next step is
performed.
(1) The operation of the block START step (without END check) is described below.
(a) When activated, the block START step (without END check) starts the specified block.
(b) After starting the specified block, the step performs only the check of the transition
condition.
(c) When the transition condition is satisfied, execution proceeds to the next step without
waiting for the START destination block to end.
(2) A simultaneous start cannot be made for a single block.
The block that has already started cannot be started, either.
If either of the above starts is made, the following processing is performed depending on the
setting of the operation mode at block double START. *1
(Refer to Section 4.7.5 for details of the operation at block double START.)
(a) When the setting of the operation mode at block double START is "STOP"
A "BLOCK EXE. ERROR" (error code: 4620) occurs and the CPU module stops
processing.
(b) When the setting of the operation mode at block double START is the default setting of
"WAIT"
Processing is not performed and waits until the START destination block ends its execution.
POINTS
*1: The Basic model QCPU and Universal model QCPU does not allow the setting of the
operation mode at block double START.
For the Basic model QCPU and Universal model QCPU, the operation mode at block
double START is "WAIT" only.
(3) A block START request can start multiple blocks simultaneously by performing a parallel
transition (refer to Section 4.3.3).
The steps in the simultaneously started blocks are processed in parallel.
(4) The number of steps that can be executed simultaneously is a total of up to 1280 steps*2 for
all blocks.
The number of steps that can be executed simultaneously in a single block is a maximum of
256 steps*3 including those of the HOLD steps.
*2: Up to 1024 steps for the Basic model QCPU and Universal model QCPU (Q02UCPU only).
*3: Up to 128 steps for the Basic model QCPU and Universal model QCPU (Q02UCPU only).
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Bm
(When transition condition
is satisfied)
MELSEC-Q
Block m
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