758
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
34 SFC Program and Step Ladder
34.1 SFC Program
3. Example of cam shaft turning control
The limit switches X013 and X011 are provided in
two positions, large forward rotation angle and small
forward rotation angle.
The limit switches X012 and X010 are provided in
two positions, large backward rotation angle and
small backward rotation angle.
When the start button is pressed, the cam shaft
performs the operation “small forward rotation
→
small backward rotation
→
large forward rotation
→
large backward rotation”, and then stops.
The limit switches X010 to X013 are normally OFF.
When the cam shaft reaches a specified angle, a
corresponding limit switch turns ON.
• When M8047 turns ON, the operation state
monitoring becomes valid. If either one among
S0 to S899 and S1000 to S4095 is ON, M8046
turns ON after the END instruction is executed.
• This SFC program adopts latched (battery
backed) type state relays so that the operation is
restarted from this process when the start button
is pressed even after the power is interrupted in
the middle of operation. However, all outputs
except Y020 are disabled until the start button is
pressed.
<M8034: All outputs disable>
When M8034 is set to ON, all outputs to the outside turn OFF even though the PLC is executing each
program in RUN mode.
M
Large backward
rotation
Origin
Small forward
rotation
Large forward
rotation
Small backward
rotation
Y023
Backward
rotation
Y021
Forward
rotation
X010
X011
X013
X012
X000
Start
M8000
Ladder
block
521
6
1
0
X000
M8047
RUN monitor
M8002
M8040
Initial pulse
M8040
X000
Start
All outputs disable
522
2
523
3
524
RET
END
SFC
block
M8002
S6
SET
Y020
M8034
M8046
Initial pulse
STL
state
ON
4
6
Start
X011
Small forward
rotation
Y023
X010
Small backward
rotation
Y021
X013
Large forward
rotation
Y023
X012
Large backward
rotation
Y021
TRAN
Y020
Origin
indication
TRAN
Y021
Forward
rotation
TRAN
Y023
Backward
rotation
TRAN
Y021
TRAN
Y023
Enable STL
monitoring
STL
transfer
disable
Initial state relay
Forward
rotation
Backward
rotation