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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
4.3.3 Parallel transition
“Parallel transition” is the transition format in which several steps linked in parallel are processed
simultaneously when the relevant transition condition is satisfied.
Branch
Step “n”
(operation output [A])
Transition condition “b”
Step “n+1”
(operation
output [B])
Step “n+3”
(operation
output [D])
Step “n+2”
(operation
output [C])
Step “n+4”
(operation
output [E])
Transition condition “c” Transition condition “d
• From step “n”, processing will proceed
simultaneously to steps “n+1” and “n+3” when
transition condition “b” is satisfied.
• Processing will proceed to step “n+4” when
transition condition “c” is satisfied, and to step
“n+4” when transition condition “d” is satisfied.
Coupling
Step “n”
(operation
output [A])
Transition condition “b”
Waiting step
Waiting step
Step “n+2”
(operation
output [C])
Step “n+1”
(operation
output [B])
Transition condition “d”
Transition condition “c”
• When transition conditions “b” and “c” are
satisfied at step “n” and step “n+1” execution,
steps “n” and “n+1” will be deactivated, and
processing will proceed to the waiting steps.
• Waiting steps are used to synchronize parallel
processing operations. Parallel processing
steps always proceed to a waiting step. When
condition “d” is satisfied at the waiting steps,
processing will proceed to step “n+2”.
• Waiting steps are dummy steps which require
no operation output ladder.
(1) Up to 32 steps can processed simultaneously with the parallel transition format.
Step “n”
Step
“n+1”
Step
“n+2”
Step
“n+32
Step
“n+3”
Step
“n+4”
Up to 32 steps