Hardware Stroke Limit Function - Mitsubishi MELSEC QD75P User Manual

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.
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.
Hardware stroke limit switches are normally installed inside the stroke limit/stroke end
on the drive unit side, and the control is stopped before the stroke limit/stoke end on
the drive unit side is reached.
The details shown below explain about the "hardware stroke limit function".
[1] Control details
Mechanical stopper
Drive unit
stroke limit
DANGER
!
[1] Control details
[2] Wiring the hardware stroke limit
[3] Precautions during control
[4] When the hardware stroke limit is not used
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
Fig. 12.19 Hardware stroke limit function operation
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Upper limit
Start Start
Movement direction
Deceleration stop at
lower limit switch detection
Upper limit switch
12 - 32
MELSEC-Q
Mechanical stopper
QD75
Drive unit
stroke limit
Drive unit