Mitsubishi Electronics FX3G User Manual

783

/FX

3GC

/FX

3UC

Series

Programming Manual - Basic & Applied Instruction Edition

35 SFC Program and Step Ladder

35.1 SFC Program

FNC277

-F

NC2
79

Trans
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FNC28

0-F

NC
289

igh-Speed

Process

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FNC2

90-
FNC299

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on Fi
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ontrol

C300-

FNC30

-C

F-

SFC

•STL

Programming

Interrupt

Function

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Inform

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Example of flows having parallel branches and recombination

1. Operation of parallel branch

• Branches in which all flows proceed at the same time are called parallel

branches.

• In the example shown on the left, when X000 turns ON while S20 is ON,

S21, S24 and S27 turn ON at the same time and the operation is started in
each flow.

• When the operation is finished in each flow and X007 turns ON, the

recombination state relay S30 turns ON. S23, S26 and S29 turn OFF.

• Such recombination is sometimes called wait recombination.

(The original flow continues its operation until all flows finish their
operations and join the original flow.)

When the parts A, B and C are processed in parallel and then assembled
afterward, flows having parallel branches and recombination are used.

2. Example of pushbutton type crosswalk

A pushbutton type crosswalk shown in the figure below can be expressed in flows having parallel branches and
recombination.
Y003: Green Y002: Yellow Y001: Red

The SFC program for a pushbutton type crosswalk is as shown below. In this example, a partial flow (jump to a state
relay located in an upper position) is repeated for blinking the green lamp on the crosswalk.
• When the PLC mode is changed from STOP to RUN, the initial state relay S0 turns ON. Normally, the green lamp is

ON for the road and the red lamp is ON for the sidewalk.

• When the crossing button X000 or X001 is pressed, the state relay S21 specifies “road: green” and the state relay

S30 specifies “sidewalk: red”. The signal lamp status is not changed.

• 30 seconds later, the yellow lamp turns ON for the road. 10 seconds later after that, the red lamp turns ON for the

road.

• When the timer T2 (5 seconds) reaches timeout after that, the green lamp turns ON for the sidewalk.
• 15 seconds later, the green lamp starts to blink for the sidewalk. (S32 turns OFF the green lamp, and S33 turns ON

the green lamp.)

• While the green lamp is blinking, S32 and S33 turn ON and OFF repeatedly. When the counter C0 (set value: 5)

turns ON, S34 turns ON. 5 seconds after the red lamp turns ON for the sidewalk, the signal lamps return to the
initial state.

• Even if the crossing button X000 or X001 is pressed in the middle of operation, the pressing is ignored.

TRAN

X000

TRAN

X007