Mitsubishi Q Series Programming Guide

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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
4.5.5 Continuous transition bit
The continuous transition bit specifies whether the operation output of the next step will be
executed in the same scan or not when the transition condition is satisfied.
(1) There are two types of SFC program transition processing: "with continuous transition" and
"without continuous transition".
The user specifies either of them by turning ON/OFF the continuous transition bit.
• Continuous transition ON (Continuous transition bit: ON)
............ When the transition conditions at contiguous steps are satisfied, all the steps
transition conditions will be executed at once within a single scan.
• Continuous transition OFF (Continuous transition bit: OFF)
..............Steps are executed in a 1-step-per-scan format.
Example: Sample program processing
aSM400 (Always ON)
aSM400 (Always ON)
aSM400 (Always ON)
(Block “n”)
• Continuous transition ON
When the corresponding block becomes active, the
processings of all steps are executed in the same scan, and
end step processing is performed to deactivate the block.
• Continuous transition OFF
When the corresponding block becomes active, steps are
executed in a 1-step-per-scan format, and end step
processing is performed in the third scan to deactivate the
block.
(2) A continuous transition can be designated for individual blocks by the continuous transition bit
ON/OFF setting, or for all blocks using the batch setting special relay.
As indicated below, whether a continuous transition is executed or not changes depending on
the combination of the continuous transition bit and the special relay that sets "whether
continuous transition of all blocks is executed or not" (SM323).
SM323 status Continuous Transition Bit Status SFC Program Operation
• Continuous transition bit OFF • Operation occurs without continuous transition
• No continuous transition bit setting
ON
• Continuous transition bit ON
• Operation occurs with continuous transition
• Continuous transition bit OFF
• No continuous transition bit setting
• Operation occurs without continuous transition
OFF
• Continuous transition bit ON • Operation occurs with continuous transition
POINT
The tact time can be shortened by setting "with continuous transition".
This resolves the problem of waiting time from when the transition condition is satisfied until
the operation output of the transition destination step is executed.
However, when "with continuous transition" is set, the operations of the other blocks and
sequence program may become slower.

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English