Learning to Use the FX Family for Positioning Control MELSEC FX PLC positioning
4 - 12
MITSUBISHI ELECTRIC
Programming example for a FX
3G
, FX
3GC
, FX3
GE
or FX
3U(C)
PLC
The following program is similar to the previous one except that it is programmed only in ladder logic
and does not follow a specific sequence of step ladder states. Additionally, it includes control for rel-
ative positioning with JOG(+) and JOG(-) commands, a DOG search zero return function, and utiliza-
tion of the DTBL instruction.
When using an FX
3G
, FX
3GC
, FX
3GE
, or FX
3U(C)
PLC, the DOG search zero return function can be pro-
grammed with limit switches wired to the PLC as follows
The DTBL instruction helps to simplify the programming and is set up beforehand (along with posi-
tioning parameters such as the bias speed, acceleration/deceleration, etc.) with GX Developer, GX IEC
Developer or GX Works2.
In this example, positioning may be performed arbitrarily along the path in fig. 4-8.
Using the JOG command, the workpiece is moved to any relative position. This is not illustrated in the
figure below.
Required hardware and software are as follows:
● FX
3G
, FX
3GC,
FX
3GE
PLC
or
● FX
3U(C)
PLC version 2.20 or later
● GX Developer 8.23Z or later
or
● GX IEC Developer
or
● GX Works2
413060da.eps
Fig. 4-7:
Configuration example
Fig. 4-8:
Positioning pattern
413070da.eps
Reverse rotation limit 2
(Servo amplifier side)
Forward rotation limit 2
(Servo amplifier side)
Reverse rotation
Forward rotation
Servo motor
Forward rotation limit 1
(Programmable
controller side)
LSF
Reverse rotation limit 1
(Programmable
controller side)
LSR
Origin after
zero return
Forward
positioning
Reverse
positioning
Output pulse frequency:
100,000 Hz
100
Acceleration/deceleration time:
100 ms
Bias speed
500 Hz
500 Hz
500,000
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