Mitsubishi Q Series Programming Guide

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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
(3) The continuous transition disable flag (SM324) is always ON (turned ON automatically by the
system at SFC program execution) normally, but is OFF during continuous transition.
Use of SM324 under the AND condition in a transition condition disables a continuous
transition.
(Example)
[SFC program]
S1
S2
S3
S4
aM0
aM0
aM0 & aSM324
[Operation]
1) When M0 is ON, step 1 to step 4 are the targets of continuous transition.
2) Since SM324 is added as the AND condition to the transition condition following step 3,
the transition condition following step 3 is not satisfied after execution of step 3.
3) When step 3 is executed in the next scan, execution proceeds to step 4 in the same
scan since SM324 is ON.
POINT
(1) When a jump transition or selection coupling causes a transition from multiple steps to one
step, the operation output of one step may be executed twice in a single scan.
(Step 1) (Step 2)
Condition
satisfied
Condition
satisfied
Condition
satisfied
(Step 3)
(Step 4)
When the setting is "with continuous transition" in the
case as shown on the left, execution passes through
step 3 twice in a single scan.
(2) In the case of "with continuous transition", a step start/end is made within one scan. Since
the END processing is not executed in this case, the coil output turned on by the OUT
instruction in the operation output is not reflected on the device. When the coil output is the
Y output, actual output is not provided. In addition, ON of the step relay cannot be
detected.
(3) In the case of a program that uses a jump transition for looping, care must be taken when
the transition conditions in the loop are all satisfied during execution at the "with continuous
transition" setting, since an endless loop will occur within one scan, resulting in WDT Err.
(No. 5001).

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English