Important Points - Mitsubishi Electric Melsec-F FX3GC Series User Manual

FX /FX /FX /FX /FX
3S 3G 3GC 3U 3UC
Built-in Positioning Functions
6.3.4

Important Points

• If an input X000 to X007 (X000 to X005 for FX
(DOG), the PLC interruption function will be used to stop the operation.
Under the following condition, however, operation may be affected by the input filter or the scan time of the
sequence program.
- An input number of X010 or higher (or other device (auxiliary relay, etc.)) is specified.
If input relay X010 or higher is specified for the near-point signal (DOG), the effects of the input filter will
be applied.
• If an input X000 to X007 (X000 to X005 for FX
(DOG), the input cannot be used for the following items:
- High-speed counter
- Input interruption
- Pulse catch
- SPD instruction
- DSZR instruction
- DVIT instruction
• Properly set the DOG so that the near-point signal (DOG) can be kept ON until the speed is reduced to the
creep speed.
This instruction will start speed reduction at the front end of the DOG, and will stop the operation at the rear
end of the DOG. The current value register will then be cleared (reset to "0").
If the speed is not reduced to the creep speed before detecting the rear end of the DOG, the operation may
not be stopped at the specified position.
• The creep speed should be sufficiently slow.
The zero return instruction will not decelerate at the stop point. Therefore, if the creep speed is not slow
enough, the operation may not stop at the specified position due to inertia.
• The DOG search function does not apply for this instruction. Therefore, start the zero return operation on
the front side of the near-point signal. If it is necessary to use the DOG search function, use the DSZR
instruction.
• The zero-phase signal of the servo motor cannot be used. For this reason, if fine adjustment of the origin
position is needed, adjust the position of the near-point signal (DOG).
• If the instruction activation contact is turned off during zero return operation, the speed will decelerate and
the operation will stop. In this case, the "Instruction execution complete" flag (M8029) will not turn on.
• While the "pulse output monitor" (BUSY/READY) flag is on, a positioning instruction (including PLSR and
PLSY) that uses the same output cannot be executed.
If the "pulse output monitor" (BUSY/READY) flag is still on after the instruction activation contact is turned
off, do not execute a positioning instruction (including PLSR and PLSY instructions) that uses the same
output number.
• In the following case, the "Instruction execution abnormal end" flag (M8329) will be turned on, and
execution of the instruction will be completed.
For details on the "Instruction execution abnormal end" flag, refer to Subsection 4.7.4.
- If the forward limit relay or the reverse limit relay is turned on, the speed will decelerate and the
operation will stop. In this case, the "Instruction execution abnormal end" flag (M8329) will be turned on
when execution of the instruction is complete.
- If the limit relay (forward or reverse) on the opposite side of the operation direction is turned on, the
speed will decelerate and the operation will stop.
In this case, the "Instruction execution abnormal end" flag (M8329) will be turned on when execution of
the instruction is complete.
• FX /FX /FX
3S 3G
Set the CLEAR signal detection to "While on, droop pulses are always cleared" for connected amplifiers
(drivers).
The stop position may deviate if it is set to "Droop pulses are cleared on the leading edge".
*1. Only available for FX
B - 116
PLC User's Manual - Positioning Control Edition
*1
PLCs operate in the sequence "CLEAR signal output  Pulse output stop".
3GC
and FX PLCs.
3U 3UC
6 Mechanical Zero Return - DSZR/ZRN Instruction
For important programming points, refer to Section 4.7.
PLC) of the main unit is specified for the near-point signal
3S
PLC) of the main unit is specified for the near-point signal
3S
6.3 Zero Return (ZRN Instruction)