Block Start Step (Without End Check) - Mitsubishi Electric MELSEC-Q Series Programming Manual

Number of concurrently active steps
The following table indicates the number of steps that can be executed simultaneously in all blocks and the maximum number
of active steps in a single block.
CPU module type
Basic model QCPU
High Performance model QCPU
Process CPU
Redundant CPU
Universal model QCPU Q00UJCPU, Q00UCPU, Q01UCPU, Q02UCPU
Q03UDCPU, Q03UDVCPU, Q03UDECPU,
Q04UDHCPU, Q04UDVCPU, Q04UDEHCPU,
Q06UDHCPU, Q06UDVCPU, Q06UDEHCPU,
Q10UDHCPU, Q10UDEHCPU, Q13UDHCPU,
Q13UDVCPU, Q13UDEHCPU, Q20UDHCPU,
Q20UDEHCPU, Q26UDHCPU, Q26UDVCPU,
Q26UDEHCPU, Q50UDEHCPU,
Q100UDEHCPU
LCPU L02SCPU, L02SCPU-P, L02CPU, L02CPU-P
L06CPU, L06CPU-P, L26CPU, L26CPU-P,
L26CPU-BT, L26CPU-PBT
• The block START step (with END check) cannot be described immediately before the coupling of a parallel
coupling. (The block START step (with END check) cannot be used for a wait.) The block START step
(without END check) can be described immediately before the coupling of a parallel coupling.
• The execution status of each block can be checked at another block using the block START/END bit of the
SFC information devices or the block activation check instruction of the SFC control instructions.

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.
Operation of block START step (without END check)
• When activated, the block START step (without END check) starts the specified block.
• After starting the specified block, the step performs only the check of the transition condition.
• When the transition condition is satisfied, execution proceeds to the next step without waiting for the START destination
block to end.
Number of steps that can be
executed simultaneously in
all blocks
1024 steps
1280 steps
1024 steps
1280 steps
1024 steps
1280 steps
4 SFC PROGRAM CONFIGURATION
Maximum number of active
steps in one block
128 steps
256 steps
128 steps
256 steps
128 steps
256 steps
4.2 Steps
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