MELSEC FX PLC positioning Learning to Use the FX Family for Positioning Control
FX Positioning Control Systems 4 - 3
Applicable
Model
Description
Positioning
instruction
Instruction Illustration
FX
1S
FX
1N
FX
3G
FX
3GC
FX
3GE
FX
3S
FX
3U
FX
3UC
1-speed positioning
A start command acceler-
ates the motor to a con-
stant speed and moves the
workpiece to a specified
distance.
DRVI
DRVA
FX
1S
FX
1N
FX
3G
FX
3GC
FX
3GE
FX
3U
FX
3UC
Zero return
The machine moves at a
specified speed until the
DOG input turns ON. The
workpiece then slows to
creep speed and stops
before the CLEAR signal is
output.
ZRN
FX
1S
FX
1N
FX
3G
FX
3GC
FX
3GE
FX
3S
FX
3U
FX
3UC
Variable speed operation
After starting with a speci-
fied speed, the motor can
change its speed depend-
ing on commands from the
PLC.
(For the FX
1S
and FX
1N
,
acceleration to different
speeds is approximated
with the RAMP instruction.)
PLSV
(RAMP)
FX
3U
FX
3UC
Interrupt 1-speed
positioning
When an interrupt signal
turns ON, the workpiece
travels a specific distance at
the same speed before
decelerating to stop.
DVIT
FX
3G
FX
3GC
FX
3GE
FX
3S
FX
3U
FX
3UC
DOG search zero return
The machine operates simi-
lar to the zero return
instruction except for fea-
tures to hunt for the DOG
switch and to use the
zero-phase signal.
DSZR
FX
3G
FX
3GC
FX
3GE
FX
3U
FX
3UC
Table operation
For programming simplic-
ity, position and speed data
can be organized in table
format for the DRVI, DRVA,
DVIT and PLSV instructions.
DTBL
Tab. 4-3:
Instructions for FX PLCs (2)
Speed
Operation speed
Start Target position
Travel distance
411030da.eps
CLEAR signal
Zero point return
Creep speed
Speed
Zero point DOG input ON
Start
411040da.eps
Speed
Start Speed change Speed change
411050da.eps
Speed
Start
Interrupt input
411060da.eps
Travel distance
Limit
(LSR)
DOG
Origin
Start
411070da.eps
DTBL
Y0
K1
DTBL
Y0
K2
DTBL
Y0
K3
Input
Input
Input
Row No.
Command are output at
Y000 in accordance to
the contents of the rows
1 to 3 of the table.
Axis
411080da.eps
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