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PLC User's Manual - Positioning Control Edition
Built-in Positioning Functions
4 Before Programming
4.7 Items To Be Observed in Programming
B - 72
4.7.2 STOP instruction
For the normal stop of an operation (stop after speed reduction), use the "instruction OFF" function or
"forward/reverse limit relay".
If an immediate stop is absolutely needed to avoid danger, use the pulse output stop command relay.
During execution of a positioning instruction, however, if the pulse output stop command relay is turned on,
the pulse outputting operation will be immediately stopped. This means that the motor will be stopped without
deceleration, which may damage the system. For this reason, take caution when using the pulse output stop
command relay.
*1. Y002 (pulse output destination) cannot be specified when the 14-point or 24-point type FX
3G PLC is
connected.
*2. Y003 can be specified as the pulse output destination only if 2 high-speed output special adapters are
connected to the FX
3U PLC.
4.7.3 Correction of Backlash
The built-in positioning function cannot correct the mechanical backlash (clearance, play). If it is necessary to
correct the backlash, preliminarily set the number of output pulses considering the backlash that may be
caused while reversing the transfer direction.
4.7.4 "Instruction execution complete" Flag of Positioning Instruction and Completion of
Positioning
If the Instruction execution complete flag (M8029) or the Instruction execution abnormal end flag (M8329) is
turned on, the execution of the instruction (pulse outputting operation, etc.) is completed. In this case,
however, it is not certain whether the servo motor has stopped. Check the "positioning completion" signal of
the servo amplifier (drive unit) to check whether the servo motor is stopped.
→ For details on "Instruction execution complete" flag and "Instruction execution abnormal end" flag,
refer to Subsection 4.4.2.
Pulse output destination
device
Pulse stop instruction Operation
Y000 M8349
During pulse outputting operation, if the pulse output stop
command relay of the corresponding pulse output
destination device is turned on, the pulse outputting
operation will immediately stop.
Y001 M8359
Y002
*1
M8369
Y003
*2
M8379
Table
Feed screw
Backlash
(clearance, play)