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8 ZERO POINT RETURN CONTROL
4)
3)
Near-point dog OFF
Zero point signal
Fig. 8.12 Count method 1) machine zero point return on the near-point dog ON position
Restrictions
A pulse generator with a zero point signal is required.
When the pulse generator is not provided with a zero point signal, create a zero
point signal with an external signal.
Precautions during operation
(1) If " Pr.52 Setting for the movement amount after near-point dog ON" is
smaller than the deceleration distance traveled from " Pr.48 Zero point return
speed" to " Pr.49 Creep speed," an error "count method movement amount
fault" (error code: 206) occurs to cause a failure to start.
(2) The following shows the operation when a machine zero point return is started
while the near-point dog is ON.
Pr.52 Setting for the movement
amount after near-point dog ON
1)
5)
2)
ON
(3) If the restart request is turned ON after zero point return is stopped upon a
stop signal, an error "zero point return restart not possible" (error code: 209)
occurs.
REMARK
With the "count method 1)" machine zero point return, return to the machine
zero point can be made at the near-point dog ON.
With the "count method 1)" machine zero point return, continuous start can be
made after return to the machine zero point is completed.
[Operation when a machine zero point return
is started at the near-point dog ON position]
1) A machine zero point return is started.
2) The machine moves at the zero point return
speed in the opposite direction of the
designated zero point return direction.
3) At near-point dog OFF detection,
deceleration process is performed according
to the setting of " Pr.40 Stop group 3 sudden
stop selection".
4) After the machine stops, a machine zero
point return is carried out in the designated
zero point return direction.
5) At detection of the first zero point after the
machine has moved the movement amount
set in " Pr.52 Setting for the movement
amount after near-point dog ON" after near-
point dog ON detection, deviation counter
clear is output and then the machine zero
point return is completed.
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MELSEC-A
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