Mitsubishi Q Series Programming Guide

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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
4.7.6 Operation mode at transition to active step (double step START)
This mode setting designates the operation mode which is to be effective when a follow-up
function such as an operation HOLD step (with transition check) is used to execute a transition to
a step which is already active.
(1) Settings and corresponding operations
For a transition to an active step, set any of STOP, WAIT and TRANSFER in the "block
parameter" of the FC setting dialog box in the Tools menu.
The operations resulting from these settings are shown below.
Setting Operation Remarks
STOP
• A CPU module operation error (BLOCK EXE.ERROR)
occurs, and CPU module operation is stopped.
• All “Y” outputs switch OFF.
• A step range can be
designated for the STOP
setting.
WAIT
• CPU module operation continues, and a WAIT status is
established when the transition condition is satisfied. The
WAIT status continues until the START destination step is
deactivated.
• If a transition WAIT occurs, the previous step is
deactivated, the output is switched OFF, and the operation
output will not be executed.
• A step range can be
designated for the WAIT
setting.
TRANSFER (default)
• CPU module operation continues, the transition occurs,
and the previous step is deactivated and absorbed by the
transition destination step.
Active step
Condition satisfied
Active step
Condition satisfied
Inactive
Active
(2) Transition to HOLD step by double START
The following table shows the transition procedure for transitions to coil HOLD steps, operation
HOLD steps (with transition check), and operation HOLD steps (without transition check)
which occur when the double START condition is satisfied. These transitions occur without
regard to the settings described at item (1) above.
Setting Operation Remarks
STOP,
WAIT,
TRANSFER
• The TRANSFER setting applies to all operations, regardless of the
setting.
• At coil HOLD steps
......... The operation output is restarted, and a transition condition
check begins.
The PLS instruction for which the input conditions have
already been established is non-executable until the input
conditions are turned on again.
• At operation HOLD steps (without transition check)
........ A transition condition check begins.
• At operation HOLD steps (with transition check)
........ Operation continues as is.
Active step
Transition condition satisfied
Inactive
Active
(No transition condition check)
Coil HOLD step or
operation output step
(without transition check)
Transition condition
is checked
• Following the double
START, execution of all
subsequent steps where
transition conditions are
satisfied will occur according
to the step attributes.

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English