Mitsubishi Q Series Programming Guide

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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
4.2.3 Dummy step
A dummy step is a waiting step, etc., which contains no operation output program.
(1) The transition condition following the corresponding step is always checked during execution
of a dummy step, and execution proceeds to the next step when the transition condition is
satisfied.
(2) The dummy step changes to a step (without step attribute, indication:
) when an operation
output program is created.
4.2.4 Coil HOLD step
SC
A coil HOLD step is a step where the coil output status is maintained in the transition to the next
step. (The coil output is switched ON by the OUT instruction when the transition condition is
satisfied.)
(1) During normal SFC program operation, the coil ON status (switched ON by OUT instruction
when transition condition is satisfied) is automatically switched OFF before proceeding to the
next step.
By designating an operation output step as a “coil HOLD step”, the coil ON status will remain
in effect when proceeding to the next step.
When designated as a coil HOLD step When not designated as a coil HOLD step
SC
Transition
condition
satisfied
oY10
(ON)
oY10
(ON)
oY10
(ON)
oY10
(OFF)Transition
condition
satisfied
• At a designated coil HOLD step, “Y10”
(switched ON by OUT instruction) will remain
ON even when the transition condition is
satisfied.
• At steps not designated as coil HOLD steps,
“Y10” (switched ON by OUT instruction) is
automatically switched OFF when the
transition condition is satisfied.
(2) No ladder processing occurs following a transition to the next step.

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English