Mitsubishi A1SD75P1-S3, User Manual

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8 - 6
MELSEC-A
8 ZERO POINT RETURN CONTROL
8.2.3 Zero point return method (1): Near-point dog method
The following shows an operation outline of the "near-point dog method" zero point
return method.
Operation chart
1)
The machine zero point return is started.
(The machine begins the acceleration designated in "
Pr.53
Zero point return acceleration time selection", in the
direction designated in "
Pr.46
Zero point return direction". It then moves at the "
Pr.48
Zero point return speed" when
the acceleration is completed.)
2) The machine begins decelerating when the near-point dog ON is detected.
3) The machine decelerates to the " Pr.49 Creep speed", and subsequently moves at that speed.
4)
After the near-point dog turns OFF, the pulse output from the AD75 will stop at the first zero point signal, outputting a
"deviation counter clear signal" to the drive unit.
5)
After a "deviation counter clear signal" is output to the drive unit, the zero point return complete flag (
Md.40
Status: b4)
turns from OFF to ON and the zero point return request flag (
Md.40
Status: b3) turns from ON to OFF.
Md.30 Machine feed value
Md.29 Current feed value
Md.44 Movement amount
after near-point dog ON
Md.35 Axis operation status
Md.44 Movement amount after near-point dog ON
t
Machine zero point return start
(Positioning start signal)
ON
OFF
Pr. 48 Zero point return speed
Deceleration at the near-point dog ON
Pr. 49 Creep speed
ON
OFF
OFF
ON
Standing by
In zero point return
Inconsistent
0
Value the machine moved is stored
Zero point address
V
Zero point signal
Value of *1.
Deviation counter clear output
Near-point dog
ON
One servomotor rotation
*
1
1) 2) 3) 4) 5)
Standing by
Inconsistent
Adjust so the near-point dog OFF position is
as close as possible to the center of the zero
point signal HIGH level.
If the near-point dog OFF position overlaps
with the zero point signal, the zero point return
stop position may deviate by one servomotor
rotation.
Zero point return request flag
[ Md.40 Status : b3]
Zero point return complete flag
[ Md.40 Status : b4]
OFF
Fig. 8.2 Near-point dog method machine zero point return
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