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12 CONTROL SUB FUNCTIONS
12.4.4 Hardware stroke limit function
When the hardware stroke limit is required to be wired, ensure to wire it in the negative logic using b-contact.
If it is set in positive logic using a-contact, a serious accident may occur.
Mechanical stopper
In the "hardware stroke limit function", limit switches are set at the upper/lower limit of
the physical moveable range, and the control is stopped (by deceleration stop) by the
input of a signal from the limit switch. Damage to the machine can be prevented by
stopping the control before the upper/lower limit of the physical moveable range is
reached.
The details shown below explain about the "hardware stroke limit function".
[1] Control details
[2] Wiring the hardware stroke limit
[3] Precautions during control
[4] When the hardware stroke limit is not used
[1] Control details
The following drawing shows the operation of the hardware stroke limit function.
Lower limit
QD75 control moveable range
Movement direction
Deceleration stop at
upper limit switch detection
Lower limit switch
None-stroke limit is input for B type servo amplifier.
Fig. 12.19 Hardware stroke limit function operation
DANGER
!
Start
Start
Movement direction
Deceleration stop at
lower limit switch detection
Upper limit switch
12 - 35
MELSEC-Q
Upper limit
Mechanical stopper
QD75
Servo amplifier
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